|
B |
Precautions to
be observed prior to starting a turbine driven cargo pump, should include
__________. |
observing the
operation of the over speed trip |
checking the manual
trip device for proper operation |
assuring that
the turbine casing drains are wired closed |
open all governor
oil relay drains |
|
A |
The slight wavy
appearance of the tips of reduction gear teeth is a result of __________. |
the method of
manufacture and does affect normal operation |
insufficient lube
oil pressure |
uneven bearing
wear due to gross misalignment |
high lube oil
temperatures |
|
D |
Which of the following
types of bearings are used as line shaft bearings? |
Rigidly mounted,
radial sleeve |
Segmental, pivoted-shoe
thrust |
Tapered roller,
split type radial |
Ring-oiled, Babbitt-faced,
spherical seat, shell |
|
D |
Which of the following
methods is used to securely fasten the Babbitt lining of a reduction gear
bearing to its shell? |
The Babbitt is
securely bonded to the shell by the pressure of the hydrodynamic oil wedge. |
The Babbitt has
a crescent shaped pocket cast symmetrically about the bearing split. |
The Babbitt is
relieved in way of the split and held in place by locking pins. |
The Babbitt is
centrifugally spun into the bearings or cast under a pressure head. |
|
D |
Babbitt is a metal
alloy commonly used for lining __________. |
saltwater piping |
valve seats |
shim stock |
precision bearings |
|
D |
Which of the following
construction methods would apply to the Babbitt lined, split-type, reduction
gear bearings? |
They are secured
in their housing so pressure points will occur at the joint faces. |
They are split
into four equal sized segments. |
They are always
mounted with the split in a horizontal plane. |
They are rigidly
mounted and dowelled in their housings. |
|
A |
The splits located
in the halves of main reduction gear bearings are aligned at an angle to
the horizontal in order to resist __________. |
wiping |
steam loss |
axial stress |
oil loss |
|
D |
Chamfers, located
at the parting edges of horizontal split sleeve type bearings, are used
to facilitate oil storage and distribution. They are machined __________. |
radially the full
length of the bearing |
radially, to within
45 degrees of the normal bearing surface |
axially the full
length of the bearing |
axially, approaching
but not extending to the end of the bearing |
|
B |
Most main propulsion
reduction gear bearings are __________. |
self-aligning,
solid bushings |
rigidly mounted,
Babbitt lined, split type |
spherical-seated,
tapered roller type |
self-lubricating,
sealed, roller ball type |
|
D |
Which of the devices
listed is commonly used to compensate for the expansion and minor misalignments
occurring between the main turbine rotor and the reduction gear? |
Quill shaft |
Expansion gear |
Sliding sleeve |
Gear type flexible
coupling |
|
C |
Axial movement
in a gear-type flexible coupling is provided for by __________. |
adjusting the
pitch of the teeth on the pinion and high speed gears |
the variable oil
clearance in the quill shaft |
gear teeth on
the floating member sliding between internal teeth on the shaft ring |
each gear sliding
on its shaft between retaining collars |
|
D |
Which of the following
statements is true concerning the coupling shown in the illustration? Illustration
SE-0001 |
It is commonly
used between the first reduction pinion and the second reduction gear. |
It is suitable
for use on small auxiliary turbines only. |
It allows for
any misalignment between the main turbine and the second reduction gear. |
It can be used
to connect the main turbine to the high-speed pinion. |
|
C |
Which of the coupling
types listed is shown in the illustration? Illustration SE-0001 |
Claw |
Pin |
Gear |
Solid |
|
B |
The part shown
in the illustration would be located between which of the following components
of a modern geared turbine main propulsion unit? Illustration SE-0001 |
Between the bull
gear and line shaft on the side of the gear opposite the thrust bearing. |
Between the rotors
and high-speed pinions of the high pressure and low pressure turbines. |
Between the bull
gear and line shaft on the thrust bearing side of the gear. |
Between the first
reduction gears and high-speed pinions of the high pressure and low pressure
turbines. |
|
C |
On main turbine
propulsion units, gear type flexible couplings are generally used between
the __________. |
quill shaft and
high speed pinion |
second reduction
and the shaft thrust bearing |
rotor shaft and
pinion shaft |
rotor shaft and
quill shaft |
|
B |
The component
shown in the illustration, labeled "I", is the __________. Illustration
SE-0013 |
first reduction
pinion |
first reduction
gear |
second reduction
pinion |
second reduction
gear |
|
D |
A ship is equipped
with the illustrated turbine gear set and a right hand turning propeller.
When steam is admitted to the astern element, with sternway on, the high-speed
gear on the high pressure side is__________. Illustration SE-0016 |
turning counter
clockwise as viewed from the aft end of the reduction gear. |
turning opposite
to the rotation of the high-speed gear on the low pressure side. |
turning the same
rotation of the high-speed pinion on the low pressure side. |
rotating the same
direction as the low-speed pinion on the low pressure side. |
|
C |
The purpose of
the main reduction gears is to __________. |
reduce engine
room noise levels during high speed operations |
transmit vibration
and thrust to the ship's hull |
reduce high turbine
RPM to an efficient propeller RPM |
provide a means
of reversing the main engines in an emergency |
|
A |
The component
shown in the illustration, labeled "IV", is the __________. Illustration
SE-0013 |
bull gear |
high speed pinion |
first reduction
gear |
low speed pinion |
|
A |
What is the significance
of pinion deflection in the operation of reduction gears? |
Pinion deflection
causes unequal tooth loading. |
Deflection is
minimal because a longer pinion is more rigid. |
Deflection causes
excessive wear at the center of the pinion. |
Deflection causes
excessive wear at both ends of the pinion. |
|
D |
After the housing
has been bolted down, the final check of reduction gear tooth contact is
usually made by __________. |
dial indicators |
alignment gauges |
bridge gauges |
bluing the teeth |
|
B |
The component
labeled "II", as shown in the illustration, is called the __________.
Illustration SE-0013 |
first reduction
gear |
high speed pinion |
second reduction
pinion |
second reduction
gear |
|
C |
The component
shown in the illustration, labeled "III", is the __________. Illustration
SE-0013 |
first reduction
gear |
second reduction
gear |
low speed pinion |
high speed pinion |
|
D |
The reduction
gear shown in the illustration is a/an __________. Illustration SE-0013 |
locked-train double
reduction gear |
nested four-step
reduction gear |
nested double
reduction gear |
articulated double
reduction gear |
|
D |
Which of the following
statements defines the term 'axial float' in reference to reduction gears? |
The gears are
capable of free motion, neither supporting nor being supported radially
by other gears. |
The gears cut
with a single helical profile have axial thrust eliminated. |
The gears are
not subject to excessive tooth loads due to mismatching of the journal bearing
halves. |
A pinion is capable
of free axial motion, mating with a fixed double helical gear which establishes
its position in the gear train. |
|
C |
As found in a
reduction gear drive system, thrust bearings serve to __________. |
increase the shaft
speed |
limit the radial
movement of the shaft |
transmit the force
produced by the propeller to the structure of the ship |
hold the main
engine in place |
|
B |
In the thrust
bearing assembly illustrated the total oil clearance can be correctly decreased
by __________. Illustration SE-0007 |
increasing the
thickness of the filler piece |
decreasing the
thickness of the adjusting ring |
decreasing the
thickness of the filler piece |
increasing the
thickness of the adjusting ring |
|
C |
In the diagrammatic
arrangement of the thrust bearing, shown in the illustration, the direction
of shaft rotation and the direction of thrust are indicated respectively
by arrows __________. Illustration SE-0012 |
F and H |
G and J |
F and J |
G and H |
|
A |
The base ring
shown in the illustration is identified by the letter __________. Illustration
SE-0012 |
D |
E |
C |
A |
|
D |
A Kingsbury, or
pivot shoe type thrust bearing, can bear much greater loads per square inch
of working surface than can parallel surface bearings because provisions
are made in the Kingsbury bearing __________. |
for automatically
adjusting clearances to the correct value when wear occurs |
for adjusting
the filler piece thickness behind the pivotal-shoes to give a more accurate
fit |
to allow the leveling
plates to pivot on the collar when thrust loads are applied |
for the shoes
to tilt slightly, thereby allowing the formation of a wedge shaped oil film
under a thrust load |
|
B |
Which of the statements
listed applies to the quill shaft shown in the illustration? Illustration
SE-0005 |
It absorbs the
axial thrust generated by the meshing gears. |
It permits axial
movement between the high speed gear and low speed pinion. |
It compensates
for high speed pinion radial misalignment. |
It provides torsional
rigidity to help maintain alignment between gear train and the turbine rotor. |
|
A |
Which of the following
operational practices is helpful in avoiding the accumulation of condensate
in the main reduction gear casing? |
After the main
unit is secured, lubricating oil should be circulated until the temperature
of the oil and reduction gear casing approximates the engine room temperature. |
Always ensure
that the lubricating oil pressure is 14-17 psi when operating in unusually
cold waters. |
Avoid applying
gland sealing steam to the low pressure turbine until you are ready to start
up the first-stage air ejector. |
The temperature
of the lubricating oil should not exceed the gear manufacturer's recommendation
when the unit is operating at full load. |
|
B |
The most practical
method of determining the condition of a shaft bearing while the shaft is
in operation is to __________. |
perform a carbon
blot test on an oil sample from the bearing |
check the lube
oil temperature |
check the lube
oil viscosity |
visually inspect
the bearing |
|
D |
Which of the listed
operational checks should be made "continuously" on the main propulsion
reduction gears? |
Check radial bearing
wear. |
Inspect alignment
between gears and turbine. |
Check teeth for
pitting and scuffing. |
Check bearing
lube oil temperatures. |
|
A |
Which immediate
action should you take when the temperature of one line shaft bearing increases
above its normal operating temperature? |
Check the bearing
for proper lubrication. |
Stop the unit
and replace the bearing. |
Check for proper
water circulation to the lube oil coolers. |
Stop the unit
and carefully inspect the bearing. |
|
C |
The most practical
method of determining the condition of a shaft bearing while the shaft is
in operation is to __________. |
perform a carbon
blot test on an oil sample from the bearing |
check the lube
oil viscosity |
check the lube
oil temperature |
visually inspect
the bearing |
|
D |
Which of the following
would cause the dowel or locking lip of a split-type, precision insert,
main bearing to shear and allow the bearing to rotate with the journal? |
Short periods
of above normal operating speeds |
Excessive bearing
bolt torque |
Unequal torque
to any two adjacent bearing bolts |
Insufficient bearing
crush |
|
A |
If a line shaft
bearing begins to overheat, the shaft speed should be reduced. If overheating
persists, you should then __________. |
apply emergency
cooling water externally to the bearing |
decrease lube
oil pressure to the bearing |
increase lube
oil pressure to the bearing |
flood the bearing
with a higher viscosity oil to provide emergency lubrication and cooling |
|
A |
While a vessel
is underway the low pressure turbine high-speed pinion is damaged. The pinion
is then removed from the gear train. Under these circumstances, the main
unit is capable of which speed and direction? |
Reduced speed
ahead only |
Reduced speed
astern and full speed ahead |
Reduced speed
astern only |
Reduced speed
ahead and full speed astern |
|
A |
What is the FIRST
thing that will happen if both the main and standby lube oil pumps fail
on a geared main propulsion turbine operating at full sea speed? |
Ahead throttle
will close. |
Lube oil sump
will overflow. |
HP turbine bearings
will overheat. |
Vacuum will be
lost. |
|
C |
Which of the following
types of bearings are used as line shaft bearings? |
tapered roller,
split type radial |
Rigidly mounted,
radial sleeve |
Ring-oiled, Babbitt-faced,
spherical seat, shell |
Segmental, pivoted-shoe
thrust |
|
A |
Babbitt is a metal
alloy commonly used for lining __________. |
precision bearings |
saltwater piping |
valve seats |
shim stock |
|
A |
The splits located
in the halves of main reduction gear bearings are aligned at an angle to
the horizontal in order to resist __________. |
wiping |
steam loss |
oil loss |
axial stress |
|
B |
Most main propulsion
reduction gear bearings are __________. |
self-aligning,
solid bushings |
rigidly mounted,
Babbitt lined, split type |
spherical-seated,
tapered roller type |
self-lubricating,
sealed, roller ball type |
|
B |
Which of the devices
listed is commonly used to compensate for the expansion and minor misalignments
occurring between the main turbine rotor and the reduction gear? |
Expansion gear |
Gear type flexible
coupling |
Quill shaft |
Sliding sleeve |
|
A |
Which of the following
statements is true concerning the coupling shown in the illustration? Illustration
SE-0001 |
It can be used
to connect the main turbine to the high-speed pinion. |
It is commonly
used between the first reduction pinion and the second reduction gear. |
It is suitable
for use on small auxiliary turbines only. |
It allows for
any misalignment between the main turbine and the second reduction gear. |
|
D |
The part shown
in the illustration would be located between which of the following components
of a modern geared turbine main propulsion unit? Illustration SE-0001 |
Between the bull
gear and line shaft on the thrust bearing side of the gear. |
Between the first
reduction gears and high-speed pinions of the high pressure and low pressure
turbines. |
Between the bull
gear and line shaft on the side of the gear opposite the thrust bearing. |
Between the rotors
and high-speed pinions of the high pressure and low pressure turbines. |
|
C |
The purpose of
the main reduction gears is to __________. |
provide a means
of reversing the main engines in an emergency |
transmit vibration
and thrust to the ship's hull |
reduce high turbine
RPM to an efficient propeller RPM |
reduce engine
room noise levels during high speed operations |
|
A |
What is the significance
of pinion deflection in the operation of reduction gears? |
Pinion deflection
causes unequal tooth loading. |
Deflection is
minimal because a longer pinion is more rigid. |
Deflection causes
excessive wear at the center of the pinion. |
Deflection causes
excessive wear at both ends of the pinion. |
|
D |
The component
labeled "II", as shown in the illustration, is called the __________.
Illustration SE-0013 |
first reduction
gear |
second reduction
pinion |
second reduction
gear |
high speed pinion |
|
B |
The reduction
gear shown in the illustration is a/an __________. Illustration SE-0013 |
locked-train double
reduction gear |
articulated double
reduction gear |
nested double
reduction gear |
nested four-step
reduction gear |
|
A |
Regarding main
reduction gears, when high speed first reduction pinions and gears are connected
to low speed pinions and gears, each contained in a sequential portion of
the gear housing, the reduction gear unit is known as __________. |
articulated |
locked train |
nested |
none of the above |
|
A |
As found in a
reduction gear drive system, thrust bearings serve to __________. |
transmit the force
produced by the propeller to the structure of the ship |
hold the main
engine in place |
increase the shaft
speed |
limit the radial
movement of the shaft |
|
A |
In the thrust
bearing assembly illustrated the total oil clearance can be correctly decreased
by __________. Illustration SE-0007 |
decreasing the
thickness of the adjusting ring |
increasing the
thickness of the adjusting ring |
increasing the
thickness of the filler piece |
decreasing the
thickness of the filler piece |
|
B |
In the diagrammatic
arrangement of the thrust bearing, shown in the illustration, the direction
of shaft rotation and the direction of thrust are indicated respectively
by arrows __________. Illustration SE-0012 |
G and J |
F and J |
F and H |
G and H |
|
B |
The base ring
shown in the illustration is identified by the letter __________. Illustration
SE-0012 |
E |
D |
A |
C |
|
C |
A Kingsbury, or
pivot shoe type thrust bearing, can bear much greater loads per square inch
of working surface than can parallel surface bearings because provisions
are made in the Kingsbury bearing __________. |
to allow the leveling
plates to pivot on the collar when thrust loads are applied |
for adjusting
the filler piece thickness behind the pivotal-shoes to give a more accurate
fit |
for the shoes
to tilt slightly, thereby allowing the formation of a wedge shaped oil film
under a thrust load |
for automatically
adjusting clearances to the correct value when wear occurs |
|
C |
Which of the statements
listed applies to the quill shaft shown in the illustration? Illustration
SE-0005 |
It provides torsional
rigidity to help maintain alignment between gear train and the turbine rotor. |
It absorbs the
axial thrust generated by the meshing gears. |
It permits axial
movement between the high speed gear and low speed pinion. |
It compensates
for high speed pinion radial misalignment. |
|
B |
Which of the following
operational practices is helpful in avoiding the accumulation of condensate
in the main reduction gear casing?
|
The temperature
of the lubricating oil should not exceed the gear manufacturer's recommendation
when the unit is operating at full load. |
After the main
unit is secured, lubricating oil should be circulated until the temperature
of the oil and reduction gear casing approximates the engine room temperature. |
Avoid applying
gland sealing steam to the low pressure turbine until you are ready to start
up the first-stage air ejector. |
Always ensure
that the lubricating oil pressure is 14-17 psi when operating in unusually
cold waters. |
|
B |
The most practical
method of determining the condition of a shaft bearing while the shaft is
in operation is to __________.
|
(a) visually inspect
the bearing |
check the lube
oil temperature |
check the lube
oil viscosity |
perform a carbon
blot test on an oil sample from the bearing |
|
B |
Which of the listed
operational checks should be made "continuously" on the main propulsion
reduction gears?
|
Check radial bearing
wear. |
Check bearing
lube oil temperatures. |
Inspect alignment
between gears and turbine. |
Check teeth for
pitting and scuffing. |
|
B |
Which immediate
action should you take when the temperature of one line shaft bearing increases
above its normal operating temperature? |
Stop the unit
and replace the bearing. |
Check the bearing
for proper lubrication. |
Stop the unit
and carefully inspect the bearing. |
Check for proper
water circulation to the lube oil coolers. |
|
B |
The most practical
method of determining the condition of a shaft bearing while the shaft is
in operation is to __________. |
perform a carbon
blot test on an oil sample from the bearing |
check the lube
oil temperature |
check the lube
oil viscosity |
visually inspect
the bearing |
|
C |
Which of the following
would cause the dowel or locking lip of a split-type, precision insert,
main bearing to shear and allow the bearing to rotate with the journal? |
Unequal torque
to any two adjacent bearing bolts |
Short periods
of above normal operating speeds |
Insufficient bearing
crush |
Excessive bearing
bolt torque |
|
A |
If a line shaft
bearing begins to overheat, the shaft speed should be reduced. If overheating
persists, you should then __________. |
apply emergency
cooling water externally to the bearing |
increase lube
oil pressure to the bearing |
flood the bearing
with a higher viscosity oil to provide emergency lubrication and cooling |
decrease lube
oil pressure to the bearing |
|
A |
Most auxiliary
turbines do not require an external source of gland sealing steam because
they __________. |
exhaust to pressures
above atmospheric pressure |
operate at relatively
low pressures |
operate with only
a small amount of axial thrust |
utilize carbon
packing rings at the low pressure end |
|
A |
Turbine throttling
losses can best be described as a loss of energy occurring __________. |
as steam passes
through the steam admission valve and there is a drop in pressure without
the performance of work |
whenever there
is leakage of steam from one stage to another through the throttle valve
packing gland |
as a result of
friction created when steam passes through the nozzle block |
as a result of
fluid friction caused by frequently throttling the turbine wheel and blade
speed |
|
C |
An excess pressure
governor is a special type of control device which would normally be found
on a __________. |
forced draft fan |
main circulator
pump |
turbine-driven
feed pump |
low pressure propulsion
turbine |
|
B |
The over speed
tripping device installed on an auxiliary turbine is automatically actuated
by __________. |
hydraulic pressure |
centrifugal force |
pneumatic force |
high back pressure |
|
D |
Carbon ring packing
segments are secured in a shaft gland assembly of a steam turbine by means
of __________. |
centering rings |
labyrinth rings |
steam pressure |
garter springs |
|
C |
Packing rings
installed on auxiliary turbines are generally lubricated by __________. |
separate lube
oil lines |
a water leak off
line |
moisture in the
turbine steam |
a salt water service
line |
|
A |
Which type of
packing is primarily utilized to control steam leakage from the casing of
a modern auxiliary turbine? |
labyrinth |
Teflon |
dovetail |
carbon |
|
C |
When fitting new
carbon ring packing on a turbine rotor shaft, carefully filing the ends
of the segments will __________. |
provide for a
greater oil wedge pressure |
reduce the ring
segment end clearance |
reduce the clearance
between the assembled ring segments and shaft |
reduce the possibility
of scoring the shaft |
|
B |
To test an automatic
low lube oil pressure trip on an idling turbo generator and at the same
time prevent the chance of bearing damage, you should __________. |
actuate the over
speed trip, making a note at what pressure the oil is dumped from under
the operating piston |
secure the steam
supply valve to the throttle valve and observe the oil pressure as the throttle
trips during the slowdown and ensure a supply of oil with the hand or standby
pump when the pressure drops to 2-3 psi |
ensure the standby
lube oil pump, if so equipped, is properly lined up and set in the 'auto'
mode, or the hand pump is being operated and then actuate the emergency
trip |
close the generator
steam throttle valve and then ensure a supply of oil through the hand or
standby pump when the pressure drops to 5-6 psi |
|
A |
The turbine of
a turbo-electric drive should be secured by __________. |
tripping the throttle
trip by hand |
dynamic braking
of the generator |
closing the main
steam stops |
closing the throttle
by hand |
|
C |
An auxiliary turbine
boiler feed pump should normally be stopped by __________. |
increasing the
load on the driven unit |
closing the exhaust
valve slightly |
actuating the
throttle hand tripping device |
rotating the hand
lube oil pump backwards |
|
A |
A steam driven
750 KW turbo generator has a rated speed of 1200 RPM. The over speed setting
for this unit must not exceed __________. |
1380 RPM |
1440 RPM |
1320 RPM |
1500 RPM |
|
C |
In any governor
there is a small range of speed in which no corrective action occurs. This
speed range is called the governor dead band and is caused by __________. |
excessive sensitivity
in the governor control valve |
speed droop designed
into the governor system |
friction in the
governor linkage and control valve |
speeder spring
surge in the governor servomotor system |
|
D |
Rotating flyweights,
acting against a spring force, will provide a simple type of __________. |
reducing valve |
safety valve |
feed water regulator |
governor |
|
A |
A constant speed
hydraulic governor would more than likely be installed on a __________. |
turbo generator |
main condensate
pump |
main propulsion
turbine |
main feed pump |
|
B |
Which of the following
statements describes how the main propulsion turbine overspeed relay initiates
closing of the throttle valve? |
Excessive centrifugal
force causes spring loaded fly balls to actuate a control lever. |
Excessive speed
causes an oil pump to develop sufficient pressure to open a spring loaded
relay valve which tends to close the steam control valve. |
Excessive speed
causes an increase in lube oil control temperature which actuates a solenoid
oil dump valve. |
Excessive centrifugal
force causes a spring loaded weight to trip a valve latch. |
|
A |
When starting
a turbo generator, you must provide lube oil pressure to the governor power
piston by means of __________. |
the hand operated
or auxiliary lube oil pump |
a line from the
gravity tank |
the main lube
oil pump |
a line from the
other generator |
|
D |
Which of the listed
parts illustrated in the turbo generator governing system, provides the
follow-up to prevent the nozzle valves from cycling between the fully open
and fully closed positions, with each variation in turbine speed? Illustration
SE-0009 |
O |
D |
H |
E |
|
D |
If two turbo-generators
with the same no-load speed settings are operating in parallel, the unit
whose governor has the lesser speed droop will __________. |
have poor power
response |
have poor sensitivity
characteristics |
assume the smaller
share of the load |
assume the larger
share of the load |
|
B |
Which of the listed
actions will occur when there is an increase in load on a ship service generator
equipped with a centrifugal type hydraulic governor? Illustration SE-0009 |
Steam flow to
the turbine decreases. |
More oil will
enter the operating cylinder (O). |
The governor weights
move outward. |
The operating
piston is forced to move lower. |
|
B |
A pilot valve
and servomotor are utilized in mechanical-hydraulic governing systems on
a turbo generator unit in order to __________. |
constant load
on the turbine unit |
provide sufficient
force to operate large steam lifting beam control valves |
allow parallel
operation with zero speed droop |
provide a means
of maintaining constant output voltage |
|
D |
A back pressure
trip on a ship's service turbo-generator functions to trip the turbine under
what circumstance? |
lubricating oil
pressure is too low |
gland seal leak
off pressure is too high |
amount of cooling
water to the condenser is excessive |
amount of cooling
water to the condenser is insufficient |
|
B |
The over speed
tripping device installed on an auxiliary turbine is automatically actuated
by __________. |
hydraulic pressure |
centrifugal force |
high back pressure |
pneumatic force |
|
A |
An excess pressure
governor would normally be used on a __________. |
turbine-driven
feed pump |
low pressure propulsion
turbine |
forced draft fan |
main circulator
pump |
|
A |
The constant pressure
governor of a turbine-driven feed pump maintains which of the following
pressures at a constant value for all capacities? |
Pump discharge |
Pump suction |
Turbine inlet |
Turbine exhaust |
|
B |
In addition to
causing erosion of turbine blades, slugs of water in the steam supply to
a turbine driven pump can result in __________. |
loss of load with
resultant turbine over speed |
erratic governor
operation |
thermal shock
to the bearings |
overheating of
the wearing rings |
|
C |
A turbo generator
back pressure trip can be actuated as a result of __________. |
an excessive pressure
drop through the turbine |
a steam inlet
valve being partially open |
insufficient circulating
water flow through the condenser |
excessively low
exhaust pressure |
|
A |
The main throttle
valve on a main propulsion turbine admits steam directly into the __________. |
turbine steam
chest |
nozzle diaphragm |
turbine blades |
crossover connection |
|
B |
In the illustration
of a typical ship service turbo-generator control system, the handle labeled "B"
is used to____________. Illustration SE-0009 |
pump up the lube
oil manifold |
reset the over
speed trip |
bypass the governor
control |
roll over the
high speed pinion |
|
C |
Which of the following
statements concerning the design of balanced throttle valves is correct? |
The ahead throttle
valve normally utilizes a guarding valve. |
Both ahead and
astern valves normally have a positive opening tendency. |
They commonly
use a conventional valve disc and a balance piston. |
They commonly
use two parallel seats and a balance cylinder. |
|
B |
A sequential lift,
nozzle valve control bar on a turbo generator, utilizes which of the following
operating principles? |
A servomotor,
mechanically connected to nozzle valve hand wheels, opens or closes the
valves in accordance with the type of electrical signal received. |
A lifting beam
mechanism engages nozzle valve stems of varying lengths. |
A hydraulic piston
raises or lowers individual valves according to pressure received from a
governor. |
A hydraulic piston
raises or lowers groups of valves according to pressure received from a
governor. |
|
C |
Which of the following
statements represents the significance of the differential pressure existing
between the nozzle block and steam chest of a turbo generator equipped with
a lifting beam mechanism? |
The pressure differential
eliminates the possibility of valve binding in the lifting beam.
o |
The pressure differential
requires the installation of a special biasing spring to open the
valves. |
The pressure differential
assists in seating the valves when the lifting beam is lowered. |
The pressure differential
necessitates the use of a special balance piston. |
|
D |
Which of the following
is used to hold the poppet valves closed in a turbo generators nozzle control
speed regulator? |
Oil pressure |
Springs |
Lifting beam |
Steam pressure |
|
B |
A motor driven
synchronizing device, figure "D" shown in the illustration, operated
from the generator switchboard, initiates fine adjustments to the steam
turbine speed by directly __________. Illustration SE-0009 |
raising or lowering
the nozzle block lifting beam |
changing the vertical
location of the pilot valve bushing |
increasing or
decreasing operating spring pressure |
varying the pivot
rod stroke length on the governor weight eccentric pad |
|
C |
Which of the following
statements describes how the main propulsion turbine overspeed relay initiates
closing of the throttle valve? |
Excessive centrifugal
force causes spring loaded fly balls to actuate a control lever. |
Excessive speed
causes an increase in lube oil control temperature which actuates a solenoid
oil dump valve. |
Excessive speed
causes an oil pump to develop sufficient pressure to open a spring loaded
relay valve which tends to close the steam control valve. |
Excessive centrifugal
force causes a spring loaded weight to trip a valve latch. |
|
C |
When starting
a turbo generator, you must provide lube oil pressure to the governor power
piston by means of __________. |
a line from the
other generator |
a line from the
gravity tank |
the hand operated
or auxiliary lube oil pump |
the main lube
oil pump |
|
B |
A back pressure
trip on a ship's service turbo-generator functions to trip the turbine under
what circumstance? |
amount of cooling
water to the condenser is excessive |
amount of cooling
water to the condenser is insufficient |
lubricating oil
pressure is too low |
gland seal leak
off pressure is too high |
|
D |
A pilot valve
and servomotor are utilized in mechanical-hydraulic governing systems on
a turbo generator unit in order to __________. |
provide a means
of maintaining constant output voltage |
allow parallel
operation with zero speed droop |
constant load
on the turbine unit |
provide sufficient
force to operate large steam lifting beam control valves |
|
C |
Which of the listed
parts illustrated in the turbo generator governing system, provides the
follow-up to prevent the nozzle valves from cycling between the fully open
and fully closed positions, with each variation in turbine speed? Illustration
SE-0009 |
H |
O |
E |
D |
|
B |
Which of the listed
actions will occur when there is an increase in load on a ship service generator
equipped with a centrifugal type hydraulic governor? Illustration SE-0009 |
The governor weights
move outward. |
More oil will
enter the operating cylinder (O). |
Steam flow to
the turbine decreases. |
The operating
piston is forced to move lower. |
|
A |
The over speed
tripping device installed on an auxiliary turbine is automatically actuated
by __________. |
centrifugal force |
pneumatic force |
high back pressure |
hydraulic pressure |
|
B |
An excess pressure
governor would normally be used on a __________. |
low pressure propulsion
turbine |
turbine-driven
feed pump |
forced draft fan |
main circulator
pump |
|
A |
The constant pressure
governor of a turbine-driven feed pump maintains which of the following
pressures at a constant value for all capacities? |
Pump discharge |
Turbine inlet |
Turbine exhaust |
Pump suction |
|
A |
A sequential lift,
nozzle valve control bar on a turbo generator, utilizes which of the following
operating principles? |
A lifting beam
mechanism engages nozzle valve stems of varying lengths. |
A servomotor,
mechanically connected to nozzle valve hand wheels, opens or closes the
valves in accordance with the type of electrical signal received. |
A hydraulic piston
raises or lowers groups of valves according to pressure received from a
governor. |
A hydraulic piston
raises or lowers individual valves according to pressure received from a
governor. |
|
C |
Which of the following
statements represents the significance of the differential pressure existing
between the nozzle block and steam chest of a turbo generator equipped with
a lifting beam mechanism? |
The pressure differential
necessitates the use of a special balance piston.
o |
The pressure differential
requires the installation of a special biasing spring to open the
valves. |
The pressure differential
assists in seating the valves when the lifting beam is lowered. |
The pressure differential
eliminates the possibility of valve binding in the lifting beam. |
|
B |
Which of the following
is used to hold the poppet valves closed in a turbo generators nozzle control
speed regulator? |
Springs |
Steam pressure |
Lifting beam |
Oil pressure |
|
C |
A motor driven
synchronizing device, figure "D" shown in the illustration, operated
from the generator switchboard, initiates fine adjustments to the steam
turbine speed by directly __________. Illustration SE-0009 |
varying the pivot
rod stroke length on the governor weight eccentric pad |
increasing or
decreasing operating spring pressure |
changing the vertical
location of the pilot valve bushing |
raising or lowering
the nozzle block lifting beam |
|
D |
The maximum temperature
rise of oil passing through any reduction gear set, or bearing, should not
exceed __________. |
90°F (44.5°C) |
30°F (16.7°C) |
70°F (38.9°C) |
50°F (27.8°C) |
|
C |
A common method
of preheating main turbine lube oil prior to rolling over the main unit
would be to __________. |
bypass the lube
oil gravity tank |
run both the lube
oil pumps simultaneously |
operate the lube
oil purifier on the main lube oil sump |
slightly increase
gland sealing steam pressure |
|
C |
Which of the following
types of bearing lubrication schemes can carry the highest unit loading? |
Ring lubricated |
Disk lubricated |
Pressure lubricated |
Oil whip lubricated |
|
D |
As lube oil absorbs
moisture its dielectric strength can be expected to __________. |
increase with
a decrease in viscosity |
increase with
an increase in viscosity |
remain the same |
decrease |
|
B |
When the temperature
of the main turbine lubricating oil is lowered, an increase will occur in
the __________. |
pour point |
viscosity |
flash point |
concentration
of contaminants |
|
A |
In order to maintain
the required lube oil temperature leaving a lube oil cooler, where an automatic
bypass valve is not provided, which of the following operations is correct? |
The cooling water
discharge leaving the cooler is directly regulated. |
The quantity of
lube oil to the cooler is regulated. |
The cooling water
to the lube oil cooler is directly regulated to maintain the proper lube
oil temperature. |
The lube oil velocity
from the cooler is regulated. |
|
C |
In a pressure
type main propulsion turbine lubrication system, the lube oil service pumps
normally take suction from the main sump and discharge directly to the __________. |
gravity feed tank |
main thrust bearing |
lube oil coolers |
lube oil header |
|
B |
To assure the
main propulsion turbine bearings are receiving the proper lube oil supply,
you should check the __________. |
lube oil strainer
magnets |
flow through the
sight glass at the bearing |
bull's-eye in
the gravity tank overflow |
lube oil temperature
at the cooler outlet |
|
D |
The term 'separation'
as used in oil purification refers to the removal of __________. |
oil from its additives |
solids from lube
oil |
acid contaminants
from oil |
water from a mixture
of oil liquids |
|
C |
If contaminated
lube oil were allowed to settle undisturbed in a tank, into which layers
would the contaminants separate? |
Sediment on the
bottom, oil in the middle, and water on top. |
Water on the bottom,
oil in the middle, and sediment on top. |
Sediment on the
bottom, water in the middle, and oil on top. |
Water on the bottom,
sediment in the middle, and oil on top. |
|
B |
Lube oil cannot
be efficiently filtered if it's __________. |
pump capacity
is greater than the system's needs |
temperature is
too low |
viscosity index
is too low |
pump discharge
pressure is higher than the system pressure |
|
D |
According to the
illustration, what is the normal function of the component shown? Illustration
SE-0010 |
indicate the pressure
and temperature of lube oil leaving a turbine bearing |
indicate the pressure
and flow of lube oil entering a turbine bearing |
act as a final
filter for oil entering a bearing |
indicate the temperature
and flow of lube oil leaving a turbine bearing |
|
D |
Which of the following
conditions is indicated by oil flowing through a lube oil gravity tank overflow
sight glass? |
Turbine bearing
failure has occurred. |
Insufficient oil
is being pumped to the gravity tank. |
Excessive oil
is stored in the gravity tank. |
Sufficient oil
flow is being supplied to the gravity tank. |
|
B |
The gravity tank
in a gravity lube oil system serves to __________. |
settle lube oil
prior to purifying |
maintain oil supply
for several minutes to bearings should the lube oil service pump fail |
store heated lube
oil |
supply the lube
oil service pump with a positive suction head |
|
B |
During high speed
operation of the main turbine propulsion unit, the heat absorbed by the
lubricating oil is removed by the __________. |
distillate cooler |
lube oil cooler |
lube oil purifier |
sump vents |
|
B |
What type of lube
oil cooler is shown in the illustration? Illustration GS-0122 |
Plate type |
Shell-and-tube |
Bundle and stack |
Self venting |
|
A |
Which of the following
statements is true concerning lube oil coolers? |
The pressure of
the oil is greater than that of the cooling water. |
Magnets are installed
in the tube sheets to remove metal particles. |
The pressure of
the oil is less than that of the cooling water. |
The temperature
of the oil is less than that of the cooling water. |
|
D |
If the main and
standby lube oil service pumps of the main engine fail while underway at
sea, __________. |
the turbine bearings
will immediately fail |
emergency lubrication
can be supplied through the use of the hand pump |
the reduction
gear bearings will immediately fail |
an emergency supply
of oil in the gravity tank will provide time to crash stop the turbine and
gears |
|
D |
In a pressure
type main propulsion turbine lubrication system, the lube oil service pumps
normally take suction from the main sump and discharge directly to the __________. |
main thrust bearing |
gravity feed tank |
lube oil header |
lube oil coolers |
|
B |
Magnets are installed
in the main propulsion turbine lube oil strainers to attract metal particles
released through wearing of the __________. |
Babbitt bearings |
reduction gears |
turbine blades |
turbine labyrinth |
|
B |
As the speed of
an oil lubricated ball bearing increases, fluid friction, due to churning,
generates heat. This condition may be avoided by __________. |
adding more lubricant
until the ball bearings are completely covered with a layer of oil |
reducing the quantity
of lubricant until only a mist of oil is present on the ball bearings |
maintaining a
continuous fluid level over half of the outer race |
installing oil
rings on the ball bearings |
|
D |
Which of the filters
listed will deplete the additives in lubricating oil? |
Extended area
membrane filter |
Cloth bag extractor |
Absorbent filter |
Adsorbent filter |
|
B |
Turbine lube oil
suction strainer baskets have __________. |
frame lined with
wire cloth |
coarse perforations |
fine perforations |
self-cleaning
design |
|
B |
One limiting problem
of lube oil filters restricting their use in large lube oil systems is __________. |
as the oil temperature
fluctuates during load changes their effectiveness changes inversely to
the temperature |
the associated
large pressure drop across the filter |
they easily rupture
at normal working pressures |
the need to centrifuge
the oil in addition to the use of the filter |
|
D |
Fine metallic
particles, which may originate from wear or failure of the lube oil service
pump internal parts, are prevented from contaminating the bearings served
by the lube oil system by __________. |
the change of
direction and settling action within the lube oil coolers |
batch centrifuging
the lube oil at least once a week |
the settling action
of solid matter in the gravity tank |
use of the magnetic
strainers in the lube oil service pump discharge piping |
|
A |
Of the many impurities
commonly found in marine lubricating oil, which of the following CANNOT
be removed by a centrifugal purifier at normal operating speeds and temperatures? |
Diesel fuel oil |
Metal particles |
Water |
Carbon particles |
|
C |
In order to obtain
the best performance with a lube oil purifier, the lube oil inlet temperature
should __________. |
be equal to the
normal lube oil cooler outlet temperature |
never exceed the
highest main engine bearing temperature |
be maintained
in a temperature range of 160°F to a maximum of 180°F |
be equal to main
lube oil sump temperature |
|
A |
In the operation
of a lube oil clarifier, the position of the oil-water interface should
be __________. |
non-existent |
maintained by
the number of disks in the disk stack |
maintained by
the ring dam |
maintained by
the diaphragm-type, weir control valve |
|
B |
Which of the following
statements concerning the operation of a lube oil purifier is correct? |
They should be
operated as slowly as possible to ensure a long service life. |
They should be
operated at maximum design speed and recommended operating capacity. |
They should not
be primed with water when operated as a separator. |
They should be
operated as clarifiers for optimum moisture removal. |
|
C |
A centrifuge will
satisfactorily remove which of the listed substances from lube oil? |
Fuel oil |
Diesel fuel |
Carbon particles |
Gasoline |
|
B |
The water seal
in a centrifuge, operating at normal speed, prevents the lube oil from discharging
from the water outlet. Another function of the seal is to __________. |
provide a means
of 'washing' the oil as it passes through the bowl |
provide an area
for separated water to pass and create a path to remove the water from the
bowl |
develop permanent
emulsions with the lube oil |
keep the bowl
at a temperature below that of the lube oil input |
|
C |
In order to maintain
the effectiveness of the lube oil centrifuge to remove water, the engineer
in charge should __________. |
have the centrifuge
cleaned only once every 30 days |
maintain the lube
oil input temperature at a maximum of 110°F |
take lube oil
samples each week and place in clear containers for inspection |
insure that the
oil input is always twice the output capacity |
|
C |
When water is
removed from lube oil passing through a centrifugal purifier, the water
removed will __________. |
be retained in
the bowl |
force the diameter
of the oil column within the bowl to be narrowed |
displace an equal
amount of water from the bowl seal |
displace water
from the heavy phase discharge port, but of an amount less than that removed
from the oil |
|
A |
One function of
the disks, in a disk-type centrifugal purifier, is to divide the bowl space
into many separate passages to __________. |
minimize agitation
of the oil-water mixture |
increase hydraulic
head needed for proper circulation |
completely filter
out suspended particles |
prevent bowl spindle
vibration |
|
D |
The size of the
discharge ring used for the efficient operation of a disk type purifier
is dependent upon the __________. |
viscosity of the
oil being purified |
rated capacity
of that purifier |
maximum design
speed of that purifier |
specific gravity
of the oil being purified |
|
A |
The disk stack
and tubular shaft used in a lube oil centrifugal purifier, is forced to
rotate at bowl speed by __________. |
the locating pin |
wire springs |
the drive pin |
the use of an
acme thread screw |
|
C |
In a disk type
centrifugal purifier, the contaminated oil enters the centrifuge __________. |
through the neck
of the top disk |
through the funnel
body |
at the top through
the regulating tube |
at the bottom
through the oil inlet |
|
B |
In a disk-type
lubricating oil purifier, __________. |
all dirt and sludge
are automatically discharged with the cooling water |
deterioration
of the bowl ring gasket will cause the purifier to lose its water seal |
the purifier driving
gears are lubricated by the reclaimed oil as it leaves the bowl |
sealing water
must never be supplied until after oil is fed to the unit |
|
C |
Item "Q"
in the illustration is used to __________. Illustration GS-0124 |
balance the force
distribution of the three wing device |
guide the oil
to be cleaned along the inside of the bowl for discharge |
establish the
position of the three wing within the bowl |
assist in breaking
down surface tension and thereby increase separation of solids and liquids
from the oil |
|
B |
Clean oil leaves
the centrifuge illustrated through item __________. Illustration GS-0124 |
N |
X |
V |
K |
|
D |
The rotating speed
of the tubular bowl centrifuge is more than twice that of the disk type.
The reason for this is __________. |
the friction affecting
rotation is not as significant with a narrow diameter bowl |
a narrow diameter
bowl is not effected as much by windage losses as a larger diameter bowl |
the drag bushing
is used to permit the higher speed of rotation |
to produce a nearly
equal magnitude of centrifugal force |
|
A |
Water removed
through centrifugal force in the illustrated unit is displaced from the
bowl through __________. Illustration GS-0124 |
N |
K |
X |
V |
|
A |
The three wing
device in the unit illustrated is maintained in its position by item __________.
Illustration GS-0124 |
Q |
O |
P |
R |
|
C |
Oil supply pressure
to the main lube oil header of a gravity feed lube oil system is __________. |
the sum of the
lube oil static head pressure and service pump discharge pressure |
the difference
between the lube oil static head pressure and service pump discharge pressure |
the result of
the height of the gravity tank above the manifold |
equal to the service
pump discharge pressure, since the static heads of the lines to and from
the gravity tank cancel out one another |
|
B |
Oil flowing through
the sight glass in the line between the lube oil gravity tank and main sump
indicates the __________. |
lube oil pump
is stopped |
gravity tank is
overflowing |
lube oil suction
strainer is clogged |
lube oil sump
is full |
|
D |
Which of the following
statements is true concerning the lube oil system shown in the illustration?
Illustration SE-0011 |
The gravity tank
directly provides the normal supply of oil to the turbines and gears. |
The gravity tank
overflow line leads directly to the lube oil sludge tank. |
The three-way
temperature control valve bypasses cooling water around or through the lubricating
oil cooler to maintain the desired oil temperature. |
The drains from
lube oil coolers can be directed back to the main sump, the sludge tank
or the lube oil purifier. |
|
B |
In a gravity lube
oil system, a sight glass is installed in a line near the operating platform.
This line connects the __________. |
bottom of the
gravity tank and the lube oil headers |
gravity tank overflow
and the sump |
gravity tank overflow
and the lube oil headers |
bottom of the
gravity tank and the sump |
|
C |
Which of the following
statements about gravity type lube oil systems is correct? |
Gravity tanks
are fitted with an overflow alarm. |
Any lube oil pump
failure causes immediate damage to turbine bearings. |
Gravity tank overflow
lines are lead directly to the lube oil sump. |
The discharge
from the gravity tanks flows to the lube oil pump suction. |
|
A |
On a ship equipped
with a gravity type lube oil system, which of the conditions listed will
occur FIRST if the main lube oil pump discharge pressure is lost? |
An alarm will
sound. |
The astern throttle
will immediately open. |
Lube oil will
be provided to the bearings and gears via the gravity tank overflow line. |
All bearing oil
pressure will be lost. |
|
C |
After starting
the main lube oil pump in a gravity-type lube oil system, you should verify
that the gravity tanks are full by __________. |
sounding the lube
oil sump |
sounding the gravity
tanks |
observing the
overflow sight glass |
observing the
flow from the bearings |
|
A |
In steam turbine
and reduction gear units, lube oil coolers installed in the lube oil system
are located between the __________. |
lube oil pumps
and gravity tanks |
lube oil sump
and lube oil pumps |
gravity tanks
and lube oil sump |
gravity tanks
and main unit |
|
D |
In a steam turbine
and reduction gear main propulsion plant, the alarm sensor for low turbine
oil pressure is usually installed __________. |
at a point on
the inlet side of the main bearings as close to the bearings as possible |
at a point on
the outlet side of the main bearings as close to the bearings as possible |
at the outlet
of the main thrust bearing |
at the end of
the supply line header to the bearings |
|
A |
Water retained
in the lube oil system of a main propulsion turbine installation is undesirable
because it __________. |
causes pitting
of the gear teeth |
raises the flash
point of the oil to a dangerously high level |
causes the turbine
to over speed |
results in excessive
cooling of bearing surfaces |
|
D |
Which of the following
would contribute to the formation of an oil and water emulsion, in addition
to acid formation? |
Aeration, agitation,
and heat |
Solid insoluble
particles, aeration, and heat |
Water and solid
insoluble particles |
Water, agitation,
and heat |
|
C |
If a lube oil
pump fails to build up discharge pressure, the cause could be the __________. |
bypass valve is
closed |
discharge valve
is open |
suction valve
is closed |
suction vacuum
is high |
|
A |
When the flow
of oil admitted to a disk-type centrifugal purifier is in excess of its
designed capacity, which of the following conditions will usually occur? |
The oil will discharged
through the heavy phase discharge port. |
The speed of the
centrifuge will increase. |
All water will
be retained by the purified oil being discharge. |
Oil will be present
in the water sealing line to the bowl. |
|
B |
While a vessel
is underway, which of the conditions listed would indicate a leak in the
lube oil cooler? |
Contamination
of the lube oil. |
Excessive lube
oil consumption. |
Corrosion of the
journals and bearings. |
Excessive water
discharge rate from the lube oil purifier. |
|
C |
Which of the following
conditions may exist if you detect an excessive amount of metal particles
on a main engine lube oil strainer magnet? |
Turbine shrouding
damage. |
Main shaft bearing
damage. |
Reduction gear
damage. |
Journal bearing
damage. |
|
C |
The maximum lube
oil temperature leaving a large, main propulsion steam turbine bearing should
__________.
|
be always maintained
at 130° F |
not exceed the
normal lube oil outlet temperature from the centrifugal purifier |
never exceed 170°F |
never exceed the
inlet temperature by more than 70°F |
|
D |
A cloudy or milky
appearing lube oil sample, taken from the main lubricating oil system could
be caused by __________. |
insufficient cooling
water to the lube oil cooler |
insufficient gland
sealing steam |
excessive cooling
water to the lube oil cooler |
excessive gland
sealing steam |
|
A |
Which of the following
problems will occur if a manually cleaned disk-type centrifugal lube oil
purifier contains insufficient sealing water prior to admitting oil flow
to the bowl? |
Lube oil will
discharge from the heavy phase discharge port to the sludge tank. |
The lube oil will
not be subjected to the proper centrifugal force. |
Contamination
of the lube oil by emulsification will result. |
The lube oil will
overheat and flash. |
|
C |
If saltwater leaks
into and contaminates the main lubricating oil system, which of the following
remedial actions should be taken? |
Run the engines
at idle and prevent the circulation of contaminated oil. |
Disengage the
jacking gear and allow contaminated oil to cool to engine room temperature. |
Seal off the leak
and promptly remove and replace all contaminated oil from the system. |
Locate the leak
and seal it off when time permits. |
|
B |
What is the FIRST
thing that will happen if both the main and standby lube oil pumps fail
on a geared main propulsion turbine operating at full sea speed? |
Vacuum will be
lost. |
Ahead throttle
will close. |
Lube oil sump
will overflow. |
HP turbine bearings
will overheat. |
|
D |
One function of
the disks, in a disk-type centrifugal purifier, is to divide the bowl space
into many separate passages to __________. |
increase hydraulic
head needed for proper circulation |
completely filter
out suspended particles |
prevent bowl spindle
vibration |
minimize agitation
of the oil-water mixture |
|
C |
The size of the
discharge ring used for the efficient operation of a disk type purifier
is dependent upon the __________. |
maximum design
speed of that purifier |
rated capacity
of that purifier |
specific gravity
of the oil being purified |
viscosity of the
oil being purified |
|
C |
In a disk type
centrifugal purifier, the contaminated oil enters the centrifuge __________. |
at the bottom
through the oil inlet |
through the funnel
body |
at the top through
the regulating tube |
through the neck
of the top disk |
|
D |
Clean oil leaves
the centrifuge illustrated through item __________. Illustration GS-0124 |
K |
N |
V |
X |
|
C |
Water removed
through centrifugal force in the illustrated unit is displaced from the
bowl through __________. Illustration GS-0124 |
X |
K |
N |
V |
|
B |
The three wing
device in the unit illustrated is maintained in its position by item __________.
Illustration GS-0124 |
O |
Q |
R |
P |
|
B |
Oil supply pressure
to the main lube oil header of a gravity feed lube oil system is __________. |
the sum of the
lube oil static head pressure and service pump discharge pressure |
the result of
the height of the gravity tank above the manifold |
the difference
between the lube oil static head pressure and service pump discharge pressure |
equal to the service
pump discharge pressure, since the static heads of the lines to and from
the gravity tank cancel out one another |
|
A |
Which of the following
statements is true concerning the lube oil system shown in the illustration?
Illustration SE-0011 |
The drains from
lube oil coolers can be directed back to the main sump, the sludge tank
or the lube oil purifier. |
The gravity tank
overflow line leads directly to the lube oil sludge tank. |
The gravity tank
directly provides the normal supply of oil to the turbines and gears. |
The three-way
temperature control valve bypasses cooling water around or through the lubricating
oil cooler to maintain the desired oil temperature. |
|
D |
Which of the following
statements about gravity type lube oil systems is correct? |
Any lube oil pump
failure causes immediate damage to turbine bearings. |
Gravity tanks
are fitted with an overflow alarm. |
The discharge
from the gravity tanks flows to the lube oil pump suction. |
Gravity tank overflow
lines are lead directly to the lube oil sump. |
|
D |
After starting
the main lube oil pump in a gravity-type lube oil system, you should verify
that the gravity tanks are full by __________. |
sounding the gravity
tanks |
observing the
flow from the bearings |
sounding the lube
oil sump |
observing the
overflow sight glass |
|
B |
In a steam turbine
and reduction gear main propulsion plant, the alarm sensor for low turbine
oil pressure is usually installed __________. |
at a point on
the outlet side of the main bearings as close to the bearings as possible |
at the end of
the supply line header to the bearings |
at the outlet
of the main thrust bearing |
at a point on
the inlet side of the main bearings as close to the bearings as possible |
|
C |
The maximum lube
oil temperature leaving the lube oil cooler of a main steam turbine propulsion
system should __________. |
be dictated only
by the existing sea water temperature |
be about 180°F |
never exceed 130°F |
never be more
than 60°F below the lube oil inlet temperature |
|
A |
The maximum lube
oil temperature leaving a large, main propulsion steam turbine bearing should
__________.
|
never exceed 170°F |
be always maintained
at 130° F |
never exceed the
inlet temperature by more than 70°F |
not exceed the
normal lube oil outlet temperature from the centrifugal purifier |
|
B |
When the flow
of oil admitted to a disk-type centrifugal purifier is in excess of its
designed capacity, which of the following conditions will usually occur? |
The speed of the
centrifuge will increase. |
The oil will discharged
through the heavy phase discharge port. |
Oil will be present
in the water sealing line to the bowl. |
All water will
be retained by the purified oil being discharge. |
|
A |
When an oil purification
centrifuge loses a portion of its seal, the oil can then be discharged through
the heavy phase discharge port. This is partly a result of greater __________. |
centrifugal force
being developed on the oil near the interface |
centrifugal force
being developed on the water seal at the side of the bowl |
centripetal force
being developed on the oil near the interface |
centripetal force
being developed on the water seal at the side of the bowl |
|
D |
In the illustrated
device, what would be a reason for oil being discharged from port "N"?
Illustration GS-0124 |
This would be
normal for the operation. |
The device being
operated as a clarifier. |
The ring dam size
is too small. |
The ring dam size
is too large. |
|
A |
Which of the following
problems will occur if a manually cleaned disk-type centrifugal lube oil
purifier contains insufficient sealing water prior to admitting oil flow
to the bowl? |
Lube oil will
discharge from the heavy phase discharge port to the sludge tank. |
The lube oil will
overheat and flash. |
Contamination
of the lube oil by emulsification will result. |
The lube oil will
not be subjected to the proper centrifugal force. |
|
D |
If a lube oil
pump fails to build up discharge pressure, the cause could be the __________. |
discharge valve
is open |
suction vacuum
is high |
bypass valve is
closed |
suction valve
is closed |
|
C |
If a tube should
leak in an operating main steam turbine lube oil cooler, the water will
not immediately contaminate the oil because the __________. |
second-stage discharge
valve will open |
plug type bypass
valve will open |
oil pressure is
greater than the water pressure |
cooling pump would
automatically shut off |
|
A |
While a vessel
is underway, which of the conditions listed would indicate a leak in the
lube oil cooler? |
Excessive lube
oil consumption. |
Corrosion of the
journals and bearings. |
Contamination
of the lube oil. |
Excessive water
discharge rate from the lube oil purifier. |
|
B |
While making your
rounds, you notice the main lube oil temperature to be higher than normal.
To remedy this situation, you should __________. |
open the lube
oil cooler seawater inlet valve wider |
increase the opening
of the lube oil cooler seawater discharge valve |
speed up the main
lube oil pump |
throttle in on
the lube oil cooler seawater discharge valve |
|
B |
No lube oil appearing
in the sight glass (bull's eye) of a gravity type system is a positive indication
of __________. |
failure of all
lube oil pumps |
no oil is overflowing
the gravity tank |
no oil flowing
to the bearings |
the gravity tanks
being empty |
|
A |
Which of the conditions
listed could cause an oil flow sight glass, of a main turbine bearing, to
be completely filled with oil? |
A restriction
in the oil drain line to the sump. |
Excessive air
trapped in the lube oil system. |
An increase in
oil temperature. |
Increasing the
amount of oil through the gravity tank overflow line. |
|
C |
When a sudden
increase in pressure occurs in a forced lubrication system, you should check
for a __________. |
high lube oil
sump level |
clogged lube oil
pump suction |
loss of oil flow
across one of the bearings |
ruptured tube
in the lube oil cooler |
|
B |
To determine the
extent of lube oil system contamination you would __________. |
observe the oil
flow in the sight glasses |
inspect the purifier
for separated foreign matter |
maintain a close
watch on bearing temperatures |
watch for variations
in the lube oil pump discharge pressure |
|
B |
Water retained
in the lube oil system of a main propulsion turbine installation is undesirable
because it __________. |
causes the turbine
to over speed |
causes pitting
of the gear teeth |
raises the flash
point of the oil to a dangerously high level |
results in excessive
cooling of bearing surfaces |
|
A |
A cloudy or milky
appearing lube oil sample, taken from the main lubricating oil system could
be caused by __________. |
excessive gland
sealing steam |
excessive cooling
water to the lube oil cooler |
insufficient cooling
water to the lube oil cooler |
insufficient gland
sealing steam |
|
C |
Which of the following
would contribute to the formation of an oil and water emulsion, in addition
to acid formation? |
Aeration, agitation,
and heat |
Solid insoluble
particles, aeration, and heat |
Water, agitation,
and heat |
Water and solid
insoluble particles |
|
A |
Which of the following
conditions may exist if you detect an excessive amount of metal particles
on a main engine lube oil strainer magnet? |
Reduction gear
damage. |
Main shaft bearing
damage. |
Journal bearing
damage. |
Turbine shrouding
damage. |
|
B |
Which of the following
statements represents the function the nozzle assembly performs in an impulse
turbine? |
Provides an area
where the steam is prevented from expanding prior to being directed against
the rotor blades. |
Converts the steam's
thermal energy into kinetic energy by increasing its velocity and directing
it against the rotor blades. |
Converts the potential
energy of steam into thermal energy by increasing its pressure and directing
it against the turbine blades. |
Increases the
velocity of the steam without a pressure drop across the diaphragm. |
|
B |
The labyrinth
packing ring in an interstage diaphragm of an impulse turbine is prevented
from rotating by __________. |
spring tension
exerted on retaining rings |
a horizontal key
joint extending into a slot |
steam pressure
exerted on the packing segments |
the weight of
the diaphragm acting on the packing ring |
|
A |
Shrouding on impulse
turbine blading is held in place by __________. |
peening the tenons |
circumferential
dovetails |
seal welding |
locking keys |
|
C |
Tenon peening
is a technique employed by turbine manufacturers to __________. |
secure turbine
blading to the rotor |
balance the turbine
rotor assembly |
secure shroud
bands to turbine blading. |
minimize turbine
rotor axial thrust |
|
A |
Which of the steam
losses listed would be associated with a multistage impulse turbine rather
than a multistage reaction turbine? |
Diaphragm packing
loss |
Blade and nozzle
loss |
Radiation loss |
Leaving loss |
|
C |
The purpose of
shroud bands secured to the tips of the turbine blades is to __________. |
increase blade
resistance to moisture in steam |
assist in maintaining
radial clearances |
stiffen the blades
to reduce vibration |
strengthen the
blade root fastenings |
|
C |
Steam passing
through a multistage impulse turbine does not impart any appreciable axial
thrust to the rotor. This is primarily due to the __________. |
dummy piston and
cylinder arrangement |
steam velocity
decreasing through the nozzle diaphragms |
equalizing holes
provided in the turbine wheel |
pressure drop
taking place through the moving blades |
|
C |
In an impulse
turbine, the fixed blades function to __________. |
decrease steam
velocity |
equalize pressure
differences |
change the direction
of steam flow |
prevent steam
turbulence |
|
B |
The type of turbine
shown in the illustration is classified as a __________. Illustration SE-0003 |
pressure-compounded
impulse |
velocity-compounded
impulse |
pressure-compounded
reaction |
pressure-velocity
compounded impulse |
|
D |
A pressure-velocity
compounded impulse turbine consists of __________. |
several rows of
moving blades attached to diaphragms |
velocity compounding
with reaction pressure compounding |
two or more rows
of nozzles in which no pressure drop exists |
two or more stages
of velocity compounding |
|
A |
How many Curtis
stages are contained in the turbine shown in the illustration? Illustration
SE-0003 |
1 |
2 |
3 |
only a reaction
turbine stage is shown |
|
D |
Design characteristics
of a velocity-compounded impulse turbine include the utilization of __________. |
one or more nozzles
with one row of rotating blades |
a low velocity
steam jet from a nozzle |
two or more simple
impulse stages |
a single pressure
stage with two or more velocity stages |
|
D |
Nozzle diaphragms
are installed in pressure-compounded impulse turbines to __________. |
eliminate blade
and nozzle losses |
support shrouding |
support moving
blades |
hold the nozzles
of the stage and admit steam to moving blades |
|
A |
An impulse-reaction
turbine is characterized by which of the following arrangements? |
Velocity-compounded
stages followed by reaction blading. |
Stationary nozzles
with impulse blading stages. |
Reaction blading
followed by impulse diaphragms. |
Reaction stages
followed by velocity-compounded blading. |
|
C |
The general method
of reducing turbine reaction blade vibration is by the use of __________. |
casing diaphragms |
dummy pistons |
binding wire |
casing seal strips |
|
B |
In what classification
of steam turbines are the moving blades and the adjacent fixed rows of blades
shaped to act as nozzles? |
Impulse |
Reaction |
Helical flow |
Radial flow |
|
C |
In which type
of turbine does a pressure drop exist through the fixed blades and the moving
blades? |
Curtis |
Rateau |
Reaction |
Impulse |
|
C |
An energy loss
associated with a reaction turbine, but not an impulse turbine, is __________. |
throttling loss |
windage loss |
tip leakage loss |
leaving loss |
|
A |
What is used to
compensate for the increased possibility of blade vibration occurring with
impulse turbine blading? |
Securing the blade
tips with shrouding. |
The decreased
pressure drop across the blade due to the thin tip design. |
Seal stripping
the groove within the turbine casing. |
Tuned vibration
dampers. |
|
A |
A pressure drop
occurs across both the moving and fixed blades of a reaction turbine as
a result of the __________. |
moving and fixed
blades being shaped to act as nozzles |
reversing blades
causing a velocity drop with resultant pressure drop |
interstage diaphragms
creating a nozzle effect in the steam flow |
conversion of
the thermal energy to pressure energy always resulting in a pressure drop |
|
D |
Which of the parts
listed for a reaction turbine serve the same function as the nozzles of
an impulse turbine? |
Moving blades
only |
Moving nozzles |
Fixed nozzles |
Fixed blades and
moving blades |
|
D |
Why do double
flow reaction turbines produce very little axial thrust? |
Because there
is no pressure drop across the blades. |
Because equalizing
holes are provided in the turbine wheels. |
Because partially
expanded steam is exhausted to the low pressure turbine where the expansion
is completed. |
Because the axial
thrust is developed on the rotor in opposite directions providing counterbalance. |
|
A |
What happens to
the steam as it moves across the moving blades in a reaction turbine? |
It creates an
axial thrust in the direction of the steam flow. |
It loses velocity
at constant pressure. |
It gains velocity
at constant pressure. |
It creates an
axial thrust opposing the direction of steam flow. |
|
A |
Large temperature
and pressure drops which occur in the first stage of a combination impulse
and reaction turbine are caused by steam passing through __________. |
one or more velocity-compounded
impulse stages at the high pressure end of the turbine |
a single row of
blades more than once |
a dummy piston
and cylinder to offset axial thrust |
a nozzle diaphragm
in the low pressure end of the turbine |
|
C |
Concerning the
classification of steam turbines, a cross compound designed unit __________. |
consists of one
Curtis stage and reaction blading |
is made up of
a varied assortment of impulse and reaction staging |
consists of a
high pressure turbine, crossover pipe, and low pressure turbine |
consists of reaction
stages and a dummy piston |
|
D |
In a cross-compounded
turbine propulsion plant, steam enters the __________. |
high pressure,
intermediate and low pressure units simultaneously |
high pressure
unit and then cross-flows to the condenser |
high and low pressure
units simultaneously |
high pressure
unit and then flows through a crossover to the low pressure unit |
|
B |
Why is superheated
steam used in the main propulsion turbines instead of saturated steam? |
Less specific
energy available per pound of steam. |
Greater heat energy
available per pound of steam. |
Higher pressure
available than saturated steam. |
Lower required
specific volume than saturated steam. |
|
D |
What is generally
found at the end of the low pressure turbine rotor of a cross-compound turbine
arrangement? |
Cruising turbine |
Back pressure
turbine |
High pressure
turbine |
Astern turbine |
|
C |
As steam accomplishes
work in an engine or turbine, the pressure of the steam is reduced because
it __________. |
becomes saturated
again |
diminishes in
volume |
expands in volume |
becomes superheated
again |
|
C |
When a turbine
is in operation, a rotor position micrometer is used to determine any change
in rotor __________. |
axial position
relative to the micrometer |
radial position
relative to the casing |
axial position
relative to the casing |
radial position
relative to the micrometer |
|
D |
A turbine assembly
in which steam flows in series through a high pressure turbine and then
on to a low pressure turbine, with both turbines driving a common reduction
gear through separate shafts, is classified as __________. |
tandem-compound |
dual series |
tandem, double
flow |
cross-compound |
|
B |
As steam first
enters the main propulsion turbine, which of the following energy conversions
takes place? |
mechanical to
thermal |
potential to kinetic |
chemical to thermal |
thermal to chemical |
|
A |
For a large main
propulsion turbine, the most commonly used turbine thrust bearing is the
__________. |
pivoted segmental
shoe |
overhung turbine
wheel |
self-oiling sleeve |
self-aligning
shell |
|
D |
Journal bearings
used with modern turbine rotors are manufactured in two halves in order
to __________. |
maintain axial
alignment and reduce thrust |
facilitate interchanging
with other bearing halves |
provide for positive
oil flow at all loads |
permit removal
of the bearing without removing the rotor from the turbine |
|
C |
Which of the journal
bearings listed most easily accommodates the minor turbine shaft misalignment? |
Spring bearings |
Roller bearings |
Spherically seated
bearings |
Ball bearings |
|
D |
The adjustable
spherically seated self-aligning bearing housings used in main turbines
are provided with oil deflector rings. The function of these rings is to
__________. |
ensure efficient
lubrication of the bearing |
prevent the leakage
of main steam into the oil |
direct the flow
of oil through the bearing |
prevent the external
leakage of oil out of the bearing housing |
|
C |
The correct radial
clearances between the rotor and the casing in a propulsion turbine are
maintained by the turbine __________. |
interstage packing |
thrust bearing |
journal bearings |
diaphragms |
|
C |
On a main propulsion
turbine bearing, the readings obtained with a bridge gage represent the
__________. |
blade axial clearance |
Babbitt thickness |
oil clearance
and bearing wear |
diaphragm tip
clearance |
|
C |
Main steam turbine
bearings are lined with __________. |
ferrous oxide |
cast-iron |
Babbitt |
steel |
|
C |
For a large main
propulsion turbine, the most commonly used turbine thrust bearing is the
__________. |
self-aligning
shell |
self-oiling sleeve |
pivoted segmental
shoe |
overhung turbine
wheel |
|
B |
An efficient seal
is normally obtained between the upper and lower halves of a turbine casing
by __________. |
asbestos gaskets |
precision metal-to-metal
contact |
copper gaskets |
flexible steel
seal strips |
|
C |
Turbine casing
flanges are sometimes provided with a system of joint grooving to __________. |
form a labyrinth
seal between the casing halves |
increase contact
pressure between the casing halves' flanges |
inject sealing
compound between the casing halves |
ensure perfect
alignment of casing halves |
|
B |
Allowance for
axial expansion of a steam turbine due to temperature changes is provided
for by the use of __________. |
casing flexible
joints |
a deep flexible
I beam support |
pivoted-shoe type
thrust bearings |
rotor position
indicators |
|
C |
Which of the devices
listed is found on an LP main propulsion steam turbine casing? |
HP turbine bypass
valve |
Sliding beam |
Sentinel valve |
Duplex set of
relief valves |
|
B |
The purpose of
the sentinel valve installed on a turbine casing is to __________. |
vent excess steam
to the main condenser |
warn the engineer
of excessive pressure in the low pressure turbine casing |
warn the engineer
of back flow of steam from the exhaust trunk |
relieve excess
pressure to the turbine extraction points |
|
B |
The astern element
of a main propulsion turbine is usually designed as a/an __________. |
Parsons stage,
reaction turbine |
Curtiss stage,
impulse turbine |
multiple entry,
helical flow turbine |
single entry,
double flow turbine |
|
D |
Which of the following
statements is true concerning the turbine shown in the illustration? Illustration
SE-0016 |
The low pressure
turbine is designed with reaction type stages |
The astern element
is of the Curtis type consisting of two three-row stages |
The ahead rotor
can be classified as a helical flow, Parsons type turbine |
A steam deflector
is provided between the astern element and the ahead stages of the LP turbine. |
|
C |
Labyrinth seals
used to reduce leakage around a turbine shaft are constructed of __________. |
staged rubber
composition seal stripping |
spring bound carbon
segments |
machined metallic
packing strips or fins |
braided asbestos
covered core segments |
|
A |
When turbine rotor
shafts extend through the casing, an external source of sealing steam is
used in conjunction with labyrinth packing to __________. |
seal the casing
during periods of low casing pressure |
maintain the rotor
journal temperature |
seal the casing
during periods of high casing pressure |
provide a constant
flow to the gland leak off condenser |
|
B |
The labyrinth
seals used on rotating steam turbine shafts reduces external leakage by
causing __________. |
pressure increases
through successive seal stages |
successive pressure
drops through the seal stages |
increased turbulence
through successively larger labyrinth clearances |
successive temperature
drops through the seal stages |
|
A |
Labyrinth packing
rings are installed on turbine diaphragms to minimize __________. |
interstage steam
leakage along the turbine rotor |
steam from escaping
to the atmosphere |
pressure buildup
on both sides of the diaphragm |
air leakage from
entering the turbine casing |
|
D |
Where are moisture
shields located in a main propulsion steam turbine? |
At the steam strainer
inlet |
Around throttle
valve stems |
At the inner stage
diaphragms |
After the last
stage of the ahead rotor blading |
|
A |
The jacking/turning
gear mechanism of a main propulsion geared turbine installation is normally
connected through mechanical linkage to the __________. |
high speed pinion
rotor |
low speed pinion
rotor |
low speed gear
rotor |
bull gear |
|
A |
The jacking gear
on main propulsion turbines can be used to __________. |
provide reduction
gear tooth inspection |
provide propulsion
in emergencies |
reduce turbine
speed during maneuvering |
lift the reduction
gear casing |
|
D |
The main propulsion
shaft turning gear usually connects to the free end of the high-speed high
pressure pinion because the __________. |
lubricating oil
from the high-speed pinion can easily supply the turning gears |
arrangement allows
for the use of a muff type coupling for flexibility and smooth engagement |
turning gears
are double reduction worm type and cannot mate with the low pressure high-
speed pinion |
greatest gear
ratio between the turning gear motor output and bull gear can be obtained |
|
D |
Which of the devices
listed is generally used to engage the main engine turning gear to the high-pressure
turbine high-speed pinion? |
Manually operated
band brake |
Quill shaft |
Sleeve coupling |
Manually operated
sliding jaw clutch |
|
B |
The main propulsion
turbine should be operated with the __________. |
lowest practical
chest pressure and the maximum number of nozzles possible to maintain the
desired speed |
highest practical
chest pressure and the minimum number of nozzles required to maintain the
desired speed |
lowest practical
chest pressure and the minimum number of nozzles required to maintain the
desired speed |
highest practical
chest pressure and the maximum number of nozzles possible to maintain the
desired speed |
|
A |
Operating a steam
turbine propulsion unit at medium speed, in an area with extremely cold
seawater and the main circulating pump providing full cooling water flow
to the condenser will result in __________. |
increased condensate
aeration due to the inability of the air ejectors to remove excessive air
accumulation from the condenser |
increased effectiveness
of the air ejectors due to the increased main condenser vacuum |
increased plant
efficiency due to increased condensate depression |
excellent plant
efficiency due to higher attainable vacuum |
|
B |
During normal
operation of a main propulsion turbine, the lube oil supply temperature
to the bearings should be maintained at approximately __________. |
135°F |
110°F |
72°F |
60°F |
|
B |
Before placing
the jacking gear in operation on a main turbine unit, you must always insure
that __________. |
the gland seal
steam system is operating |
the main lube
oil system is operating |
the condensate
system is operating |
the main salt
water circulating pump is operating |
|
D |
The most critical
period of main turbine operation is during cold start-up, rather than hot
shutdown because __________. |
harmonic vibrations
associated with critical speed can easily be reached during start-up |
the danger of
blade erosion damage from dry steam impingement is greater during start-up |
lubricant film
thickness during start-up is considerably less than the dimensions of gear
surface irregularities |
differential expansion
can result from the temperature difference between the rotor and rotor casing |
|
A |
Prior to rolling
the main turbines in preparation for getting underway, you should __________. |
disengage the
turning gear |
circulate the
lube oil through the emergency lube oil cooler |
secure the gland
sealing steam regulator |
open the reduction
gear casing access plates and inspect the lube oil spray pattern |
|
B |
Which of the listed
procedures should be followed when raising vacuum on the main propulsion
plant prior to getting underway? |
Start the lube
oil system, start the second-stage air ejector and the gland sealing system,
start the condensate and circulating pumps, and start the turning gear. |
Start the lube
oil system, engage the turning gear, start the condensate and circulating
pumps, start the gland sealing system and second-stage air ejector. |
Start the condensate
and circulating pumps, start the lube oil system, start the air ejectors
and the gland sealing system, and engage the turning gear. |
Start the condensate
and circulating pumps, engage the turning gear, start the lube oil system,
then start the first-and second-stage air ejectors and the gland sealing. |
|
B |
After properly
lining up the main propulsion turbine for warm up, steam should first be
admitted to the rotor through the __________. |
ahead throttle
valve |
astern throttle
valve |
LP turbine bleed
valve |
HP turbine bleed
valve |
|
A |
When a turbine
rotor is not rotating during maneuvering, the heat tends to be concentrated
at the __________. |
top of the turbine |
exhaust trunk |
turbine bleed
lines |
casing joints |
|
B |
With vacuum up
and the main propulsion turbine standing by while awaiting engine orders,
it is necessary to roll the unit alternately ahead and astern every five
minutes to __________. |
warm the astern
guarding valve and the low lube oil pressure throttle trip |
reduce the possibility
of warping the turbine rotors |
distribute the
gland sealing steam evenly throughout the glands |
slowly bring the
lube oil and bearings to operating temperature |
|
D |
To stop the rotor
of a main turbine while underway at sea you should __________. |
secure all steam
to the turbine |
tighten the stern
tube packing gland |
apply the prony
brake |
admit astern steam
to the turbine after securing the ahead steam |
|
D |
The jacking gear
must be engaged as quickly as possible when securing the Main Turbines in
order to __________. |
permit rapid cooling
of the reduction gears |
maintain a constant
supply of lube oil to the main unit |
prevent the stern
tube bearing from overheating |
prevent uneven
cooling of the turbine rotors |
|
B |
To prevent damage
to the turning gear mechanism, which of the following procedures must be
carried out before the turning gear is engaged? |
The brake on the
first reduction worm shaft must be set. |
The propeller
shaft must be stopped and held stationary until the clutch is engaged. |
The engine order
telegraph must be on 'stop'. |
The speed of the
astern turbine must be reduced. |
|
C |
When securing
a main propulsion turbine equipped with carbon packing glands, the vacuum
should always be broken before securing the gland seal steam because __________. |
gland seal leak
off lines will flood with water
o |
the turbine rotor
expands faster than the gland casing |
cold air rapidly
entering the gland may result in damage to the carbon segments and sealing
surfaces |
loop seal will
flood the after condenser |
|
D |
In securing the
main turbines, steam to the second stage air ejectors should be left on
for a short period of time in order to __________. |
insure equal cooling
of the main turbine bearings |
prevent excessive
condensate depression |
remove the excessive
amount of non-condensable vapors which accumulated during
maneuvering operations |
dry out the main
turbines |
|
D |
The FIRST step
in breaking vacuum on a main turbine unit should be to __________. |
secure the steam
to the gland seal system |
stop the main
circulating pump |
stop the main
condensate pump |
secure the steam
to the main air ejector |
|
D |
A common cause
of the Babbitt linings cracking in a turbine journal bearing is from __________. |
excessive thrust
bearing wear |
prolonged operation
at low speed |
prolonged operation
at full speed |
vibration generated
by the rotor |
|
D |
Excessive thrust
bearing wear in a main propulsion turbine rotor should FIRST become apparent
by __________. |
an intermittent
vibration when changing speed |
metal particles
in the lube oil purifier |
rubbing noises
when jacking over the main unit |
taking rotor position
indicator readings |
|
C |
The original bridge
gage reading for a reduction gear bearing was measured as 0.008 inches.
A year later, the bridge gage reading for the same bearing is 0.010 inches.
This indicates __________. |
oil clearance
is .002 inch |
bearing wear is
.010 inch |
bearing wear is
.002 inch |
oil clearance
has increased .010 inch |
|
C |
The main propulsion
turbine can be damaged by __________. |
maintaining vacuum
too high |
using the jacking
gear when there is no vacuum |
water carryover
from the boilers |
operating at slow
speeds |
|
D |
An overheated
bearing in the main propulsion unit is indicated by __________. |
bubbles in the
sight flow glasses |
sludge in the
lube oil strainers |
high level in
the lube oil sump |
high temperature
of the lube oil leaving the bearing |
|
A |
While a vessel
is underway the low pressure turbine high-speed pinion is damaged. The pinion
is then removed from the gear train. Under these circumstances, the main
unit is capable of which speed and direction? |
Reduced speed
ahead only |
Reduced speed
ahead and full speed astern |
Reduced speed
astern and full speed ahead |
Reduced speed
astern only |
|
C |
Journal bearings
used with modern turbine rotors are manufactured in two halves in order
to __________. |
facilitate interchanging
with other bearing halves |
provide for positive
oil flow at all loads |
permit removal
of the bearing without removing the rotor from the turbine |
maintain axial
alignment and reduce thrust |
|
A |
The adjustable
spherically seated self-aligning bearing housings used in main turbines
are provided with oil deflector rings. The function of these rings is to
__________. |
prevent the external
leakage of oil out of the bearing housing |
prevent the leakage
of main steam into the oil |
direct the flow
of oil through the bearing |
ensure efficient
lubrication of the bearing |
|
C |
On a main propulsion
turbine bearing, the readings obtained with a bridge gage represent the
__________. |
diaphragm tip
clearance |
Babbitt thickness |
oil clearance
and bearing wear |
blade axial clearance |
|
B |
Main steam turbine
bearings are lined with __________. |
ferrous oxide |
Babbitt |
steel |
cast-iron |
|
C |
For a large main
propulsion turbine, the most commonly used turbine thrust bearing is the
__________. |
self-oiling sleeve |
self-aligning
shell |
pivoted segmental
shoe |
overhung turbine
wheel |
|
B |
An efficient seal
is normally obtained between the upper and lower halves of a turbine casing
by __________. |
copper gaskets |
precision metal-to-metal
contact |
flexible steel
seal strips |
asbestos gaskets |
|
A |
Turbine casing
flanges are sometimes provided with a system of joint grooving to __________. |
inject sealing
compound between the casing halves |
form a labyrinth
seal between the casing halves |
ensure perfect
alignment of casing halves |
increase contact
pressure between the casing halves' flanges |
|
B |
Allowance for
axial expansion of a steam turbine due to temperature changes is provided
for by the use of __________. |
rotor position
indicators |
a deep flexible
I beam support |
casing flexible
joints |
pivoted-shoe type
thrust bearings |
|
C |
Which of the devices
listed is found on an LP main propulsion steam turbine casing? |
HP turbine bypass
valve |
Sliding beam |
Sentinel valve |
Duplex set of
relief valves |
|
B |
The purpose of
the sentinel valve installed on a turbine casing is to __________. |
vent excess steam
to the main condenser |
warn the engineer
of excessive pressure in the low pressure turbine casing |
relieve excess
pressure to the turbine extraction points |
warn the engineer
of back flow of steam from the exhaust trunk |
|
A |
The astern element
of a main propulsion turbine is usually designed as a/an __________. |
Curtiss stage,
impulse turbine |
single entry,
double flow turbine |
Parsons stage,
reaction turbine |
multiple entry,
helical flow turbine |
|
A |
Which of the following
statements is true concerning the turbine shown in the illustration? Illustration
SE-0016 |
A steam deflector
is provided between the astern element and the ahead stages of the LP turbine. |
The ahead rotor
can be classified as a helical flow, Parsons type turbine |
The astern element
is of the Curtis type consisting of two three-row stages |
The low pressure
turbine is designed with reaction type stages |
|
B |
Labyrinth seals
used to reduce leakage around a turbine shaft are constructed of __________. |
spring bound carbon
segments |
machined metallic
packing strips or fins |
staged rubber
composition seal stripping |
braided asbestos
covered core segments |
|
A |
When turbine rotor
shafts extend through the casing, an external source of sealing steam is
used in conjunction with labyrinth packing to __________. |
seal the casing
during periods of low casing pressure |
maintain the rotor
journal temperature |
seal the casing
during periods of high casing pressure |
provide a constant
flow to the gland leak off condenser |
|
B |
The labyrinth
seals used on rotating steam turbine shafts reduces external leakage by
causing __________. |
increased turbulence
through successively larger labyrinth clearances |
successive pressure
drops through the seal stages |
successive temperature
drops through the seal stages |
pressure increases
through successive seal stages |
|
D |
Labyrinth packing
rings are installed on turbine diaphragms to minimize __________. |
steam from escaping
to the atmosphere |
pressure buildup
on both sides of the diaphragm |
air leakage from
entering the turbine casing |
interstage steam
leakage along the turbine rotor |
|
D |
Where are moisture
shields located in a main propulsion steam turbine? |
Around throttle
valve stems |
At the inner stage
diaphragms |
At the steam strainer
inlet |
After the last
stage of the ahead rotor blading |
|
C |
The jacking/turning
gear mechanism of a main propulsion geared turbine installation is normally
connected through mechanical linkage to the __________. |
bull gear |
low speed gear
rotor |
high speed pinion
rotor |
low speed pinion
rotor |
|
A |
The jacking gear
on main propulsion turbines can be used to __________. |
provide reduction
gear tooth inspection |
provide propulsion
in emergencies |
reduce turbine
speed during maneuvering |
lift the reduction
gear casing |
|
A |
The main propulsion
shaft turning gear usually connects to the free end of the high-speed high
pressure pinion because the __________. |
greatest gear
ratio between the turning gear motor output and bull gear can be obtained |
turning gears
are double reduction worm type and cannot mate with the low pressure high-speed
pinion |
lubricating oil
from the high-speed pinion can easily supply the turning gears |
arrangement allows
for the use of a muff type coupling for flexibility and smooth engagement |
|
D |
Which of the devices
listed is generally used to engage the main engine turning gear to the high-pressure
turbine high-speed pinion? |
Manually operated
band brake |
Quill shaft |
Sleeve coupling |
Manually operated
sliding jaw clutch |
|
B |
Before placing
the jacking gear in operation on a main turbine unit, you must always insure
that __________. |
the condensate
system is operating |
the main lube
oil system is operating |
the gland seal
steam system is operating |
the main salt
water circulating pump is operating |
|
D |
Prior to rolling
the main turbines in preparation for getting underway, you should __________. |
circulate the
lube oil through the emergency lube oil cooler |
secure the gland
sealing steam regulator |
open the reduction
gear casing access plates and inspect the lube oil spray pattern |
disengage the
turning gear |
|
D |
After properly
lining up the main propulsion turbine for warm up, steam should first be
admitted to the rotor through the __________. |
HP turbine bleed
valve |
ahead throttle
valve |
LP turbine bleed
valve |
astern throttle
valve |
|
C |
When a turbine
rotor is not rotating during maneuvering, the heat tends to be concentrated
at the __________. |
turbine bleed
lines |
exhaust trunk |
top of the turbine |
casing joints |
|
A |
With vacuum up
and the main propulsion turbine standing by while awaiting engine orders,
it is necessary to roll the unit alternately ahead and astern every five
minutes to __________. |
reduce the possibility
of warping the turbine rotors |
warm the astern
guarding valve and the low lube oil pressure throttle trip |
slowly bring the
lube oil and bearings to operating temperature |
distribute the
gland sealing steam evenly throughout the glands |
|
D |
To stop the rotor
of a main turbine while underway at sea you should __________. |
apply the prony
brake |
tighten the stern
tube packing gland |
secure all steam
to the turbine |
admit astern steam
to the turbine after securing the ahead steam |
|
A |
To prevent damage
to the turning gear mechanism, which of the following procedures must be
carried out before the turning gear is engaged? |
The propeller
shaft must be stopped and held stationary until the clutch is engaged. |
The engine order
telegraph must be on 'stop'. |
The brake on the
first reduction worm shaft must be set. |
The speed of the
astern turbine must be reduced. |
|
D |
A common cause
of the Babbitt linings cracking in a turbine journal bearing is from __________. |
prolonged operation
at low speed |
prolonged operation
at full speed |
excessive thrust
bearing wear |
vibration generated
by the rotor |
|
C |
When a turbine
bearing shows signs of overheating, you should __________. |
increase the lube
oil pump discharge pressure |
stop the turbine |
immediately reduce
speed |
increase the cooling
water supply to the lube oil cooler |
|
A |
If steam is admitted
to the main propulsion turbine with the jacking gear engaged, which of the
following problems can occur? |
Destruction of
the jacking gear. |
Excessive tooth
stress on the high pressure first reduction pinion. |
A possibility
of shearing the jacking gear flexible coupling. |
Uneven warming
of the turbine. |
|
A |
Excessive thrust
bearing wear in a main propulsion turbine rotor should FIRST become apparent
by __________. |
taking rotor position
indicator readings |
metal particles
in the lube oil purifier |
rubbing noises
when jacking over the main unit |
an intermittent
vibration when changing speed |
|
B |
Raising vacuum
on a main turbine unit without using the turning gear will result in __________. |
excessive time
being required to raise vacuum |
uneven heat distribution
in the rotor unit |
scoring of the
rotor in way of the labyrinth packing |
overheating of
the second-stage air ejector |
|
C |
The original bridge
gage reading for a reduction gear bearing was measured as 0.008 inches.
A year later, the bridge gage reading for the same bearing is 0.010 inches.
This indicates __________. |
oil clearance
is .002 inch |
bearing wear is
.010 inch |
bearing wear is
.002 inch |
oil clearance
has increased .010 inch |
|
D |
If the main propulsion
turbine begins to vibrate severely while you are increasing speed, you should
__________. |
stop the turbine
and not answer any more bells |
open the throttle
wider to pass through the critical speed |
hold the turbine
at that speed until vibration stops |
immediately slow
the turbine to see if the vibration will stop |
|
B |
The main propulsion
turbine can be damaged by __________. |
maintaining vacuum
too high |
water carryover
from the boilers |
operating at slow
speeds |
using the jacking
gear when there is no vacuum |
|
B |
An unusual vibration
in the main propulsion turbine unit, accompanied by a rumbling sound in
the reduction gear, could be caused by __________. |
a labyrinth seal
failure |
a carryover from
the boiler |
overloading of
the condenser |
a reduction in
condenser vacuum |
|
A |
An overheated
bearing in the main propulsion unit is indicated by __________. |
high temperature
of the lube oil leaving the bearing |
bubbles in the
sight flow glasses |
high level in
the lube oil sump |
sludge in the
lube oil strainers |
|
C |
The turbine of
a turbo-electric drive should be secured by __________. |
dynamic braking
of the generator |
closing the throttle
by hand |
tripping the throttle
trip by hand |
closing the main
steam stops |
|
C |
An auxiliary turbine
boiler feed pump should normally be stopped by __________. |
closing the exhaust
valve slightly |
rotating the hand
lube oil pump backwards |
actuating the
throttle hand tripping device |
increasing the
load on the driven unit |
|
A |
The over speed
tripping device installed on an auxiliary turbine is automatically actuated
by __________. |
centrifugal force |
high back pressure |
hydraulic pressure |
pneumatic force |
|
D |
Most auxiliary
turbine feed pumps do not require an external source of gland sealing steam
because they __________. |
operate with only
a small amount of axial thrust |
operate at relatively
low pressures |
utilize carbon
packing rings at the low pressure end |
exhaust to pressures
above atmospheric pressure |
|
A |
Packing rings
installed on auxiliary turbines are generally lubricated by __________. |
moisture in the
turbine steam |
separate lube
oil lines |
a salt water service
line |
a water leak off
line |
