|
D |
The process of
supplying a diesel engine cylinder with air at a pressure greater than atmospheric
is called __________. |
engine displacement |
super-aspirating |
air injection |
supercharging |
|
A |
Forcing the exhaust
gases from the cylinder of an operating two cycle diesel engine with the
aid of a blower is known as __________. |
scavenging |
forced draft |
turbo charging |
aspiration |
|
A |
Which of the listed
types of superchargers will NOT have a volumetric capacity proportional
to engine speed? |
Exhaust gas turbocharger |
Roots blower |
Piston type blower |
Vane type blower |
|
A |
The relative air
pressure in the inlet manifold of a turbocharged diesel engine is usually
__________. |
greater than the
average exhaust manifold pressure |
less than the
average exhaust manifold pressure |
greater at the
turbine wheel than at the impeller |
greater at reduced
engine speed |
|
C |
After cooling
of a turbocharged diesel engine will result in __________. |
higher torque
but lower brake horsepower |
lower torque but
higher brake horsepower |
higher torque
and higher brake horsepower |
lower torque and
lower brake horsepower |
|
B |
The process of
scavenging a two-stroke/cycle diesel engine serves to __________. |
improve fuel flow
volume |
cool the exhaust
valves
|
reduce the intake
air charge density
|
increase the temperature
of exhaust gases |
|
B |
Why will a turbocharged
diesel engine produce black smoke if excessive additional load is applied
too quickly? |
Exhaust energy
would draw excess air. |
The inertia of
the turbocharger rotor causes a time lag which delays the turbocharger speed
increase.
|
Exhaust gas pumping
losses are increased due to turbine windage.
|
Exhaust gas back
pressure falls slightly due to increased nozzle action. |
|
D |
According to the
illustrated main engine cooling water systems drawing, which of the labeled
heat exchangers represents the charge air coolers? Illustration MO-0111 |
3 and 4 |
4 and 5 |
4 and 6 |
5 and 6 |
|
D |
Which of the following
devices will increase the power output of a diesel engine without increasing
its frictional load? |
Positive displacement
blower
o |
Roots-type rotary
blower |
Gear-driven centrifugal
blower |
Turbine-driven
centrifugal blower |
|
B |
Some diesel engines
are supercharged with a __________. |
slam charger |
turbocharger
o |
fuel atomizer
o |
fuel injector |
|
A |
The device shown
in the illustration is commonly used to __________. Illustration MO-0080 |
utilize the flow
of exhaust gases to supercharge the engine
|
protect the crankcase
from overpressure in event of explosion
|
provide cooling
water circulation through the engine
|
provide air starting
pressure |
|
B |
At rated engine
load and RPM, the diesel engine turbocharger is powered by __________. |
belt drive |
exhaust gases
|
electric motor
|
friction clutch |
|
B |
The operating
speed of a turbocharger is directly dependent upon __________. |
engine speed |
engine load
|
intake manifold
pressure
|
atmospheric pressure |
|
B |
What statement
is true concerning the charge air system of a modern turbocharged slow-speed
two-stroke cycle diesel engine? |
A mechanically
driven auxiliary blower is usually provided because the turbocharger cannot
provide enough air at low engine speeds and loads. |
An electrically
driven auxiliary blower is usually provided because the turbocharger cannot
provide enough air at low engine speeds and loads.
|
An electrically
driven auxiliary blower is usually provided because the turbocharger cannot
provide enough air at high engine speeds and loads.
|
A mechanically
driven auxiliary blower is usually provided because the turbocharger cannot
provide enough air at high engine speeds and loads. |
|
A |
What statement
is true concerning the charge air system of a modern turbocharged slow-speed
two-stroke cycle diesel engine? |
A charge air cooler
is usually provided to increase the charge air density.
o |
A charge air heater
is usually provided to decrease the charge air density.
o |
A charge air heater
is usually provided to increase the charge air density.
o |
A charge air cooler
is usually provided to decrease the charge air density. |
|
C |
On a typical turbo-charged
marine diesel engine, what type of blower/compressor is used within the
turbocharger? |
Rotary vane |
Rotary screw |
Centrifugal
o |
Axial flow |
|
D |
If oil discharges
are detected when the scavenging air receiver drains are blown on a slow-speed,
two-stroke, turbocharged, aftercooled engine, what is the most likely oil
source?
|
Turbocharger lubricating
oil |
Crosshead lubricating
oil |
Bearing lubricating
oil |
Cylinder lubricating
oil |
|
C |
Upon conducting
a machinery space round on a slow-speed main propulsion diesel, you detect
a significant amount of oil discharge when blowing down the scavenging air
receiver drains. What should you do? |
Notify the watch
or duty engineer at some point during the day work period or watch. |
Notify the chief
engineer the next time he or she is seen. |
Notify the watch
or duty engineer immediately. |
Notify the first
assistant engineer the next time he or she is seen. |
|
A |
You are asked
by the watch or duty engineer to check for any evidence for turbocharger
surging. What should you check for? |
By listening for
cyclic changes in turbocharger sound pitch. |
By visually checking
for cyclic changes in turbocharger sump oil levels. |
By visually checking
for cyclic changes in charge air temperature. |
By visually checking
for cyclic changes in exhaust gas temperature. |
|
C |
Upon conducting
a machinery space round on a main propulsion diesel, you detect a significant
amount of water discharge when blowing down the charge air cooler or scavenging
air receiver drains. What should you do? |
Notify the watch
or duty engineer at some point during the day work period or watch. |
Notify the first
assistant engineer the next time he or she is seen. |
Notify the watch
or duty engineer immediately. |
Notify the chief
engineer the next time he or she is seen. |
|
A |
During the valve
overlap period, the exhaust pressure of a turbocharged, four-stroke cycle
diesel engine must be less than the intake manifold pressure to ensure __________. |
effective cylinder
scavenging and cooling |
constant pressure
from the turbochargers |
cooler operation
of the exhaust system |
effective constant
pressure for turbocharger operation |
|
D |
The power consumed
during the scavenging process of a diesel engine is known as the __________. |
compression loss |
valve loss |
back pressure
loss |
pumping loss |
|
C |
If a slow-speed
two-stroke cycle diesel engine is fitted with exhaust valves located in
the cylinder heads, what scavenging flow-pattern is utilized? |
Cross-flow scavenging |
Return-flow scavenging |
Uniflow scavenging |
Loop scavenging |
|
A |
If a slow-speed
two-stroke cycle diesel engine is fitted with scavenging air ports and exhaust
ports located on opposite sides of the cylinder wall, what scavenging flow-pattern
is utilized? |
Cross-flow scavenging |
Uniflow scavenging |
Return-flow scavenging |
Loop scavenging |
|
D |
As it applies
to the combustion process associated with diesel engines, what is meant
by the term "scavenging"? |
Scavenging is
the process of filling the cylinder with a charge of fresh air ready for
compression. |
Scavenging is
the process of filling the cylinder with a charge of fresh air at pressures
above atmospheric pressure. |
Scavenging is
the process of filling the cylinder with a charge of fresh air at atmospheric
pressure. |
Scavenging is
the process of removing exhaust gases from the cylinder by blowing in fresh
air. |
|
C |
Corrosion inhibitors
and/or soluble oils are added to diesel engine cooling systems to __________. |
reduce the cooling
water temperature |
increase cooling
water hardness |
form a protective
film on metal surfaces |
maintain low pH
in the cooling water |
|
B |
Ethylene glycol,
when used as a coolant in a closed cooling system for a diesel engine, is
more advantageous than untreated raw water because it __________. |
has a higher freezing
point and a lower boiling point |
has a lower freezing
point and higher boiling point |
provides a constant
pH below 7 |
provides better
vapor-phase cooling |
|
B |
According to the
illustrated main engine cooling water systems drawing, which labeled pump
is the main engine sea water cooling water pump? Illustration MO-0111 |
7 |
8 |
15 |
20 |
|
B |
According to the
illustrated main engine cooling water systems drawing, which labeled heat
exchangers use sea water as a cooling medium? Illustration MO-0111 |
3, 4, 5, 6, and
23 |
3, 4, 5, 6, and
24 |
4, 5, 6, and 23 |
4, 5, 6, and 24 |
|
A |
According to the
illustrated main engine cooling water systems drawing, which labeled sea
water-cooled heat exchanger would have the highest sea water inlet temperature?
Illustration
MO-0111 |
3 |
4 |
5 |
6 |
|
B |
According to the
illustrated main engine cooling water systems diagram, which of the following
labeled heat exchangers represents the main lube oil cooler? Illustration
MO-0111 |
3 |
4 |
5 |
6 |
|
D |
According to the
illustrated main engine cooling water systems diagram, which of the following
heat exchangers would be isolated and bypassed while maneuvering in or out
of port?
Illustration MO-0111 |
3 and 4 |
4 and 5 |
5 and 6 |
23 and 24 |
|
C |
Cooling water
pumps driven by direct-reversing diesel engines are usually __________. |
curved impeller
vane with tangential outlet |
straight impeller
vane with tangential housing |
straight impeller
vane with concentric housing |
curved impeller
vane with concentric outlet |
|
A |
According to the
illustrated diesel propulsion plant fresh water cooling systems diagram,
in which subsystem is the deaerator located? Illustration MO-0072 |
Main engine cylinder
jacket cooling water system |
Main engine fuel
injector cooling water system |
SSDG cylinder
jacket cooling water system |
Main engine piston
cooling water system |
|
B |
The expansion
tank for a diesel engine closed cooling system is designed to maintain a
constant head on the system and __________. |
reduce water temperature |
allow for an increase
in water volume as the engine warms up |
reduce water turbulence |
provide an air
cushion |
|
C |
The highest pressure
in any closed diesel engine freshwater cooling system is at the __________. |
jacket water outlet |
expansion tank
inlet |
cooling water
pump outlet |
heat exchanger
inlet |
|
C |
The expansion
tank in a diesel engine closed fresh water cooling system is located at
__________. |
the lowest point
in the system |
or near the tank
top level |
the highest point
in the system |
or near the floor
plate level |
|
C |
A closed freshwater
cooling system is commonly used with marine diesel engines because the __________. |
cooling water
temperature differential is greater |
cooling water
pumps are directly reversible |
jacket water temperature
is more easily controlled |
need for water
treatment is eliminated |
|
B |
Corrosion inhibitors
and/or soluble oils are added to diesel engine cooling systems to __________. |
increase cooling
water hardness |
form a protective
film on metal surfaces |
reduce the cooling
water temperature |
maintain low pH
in the cooling water |
|
C |
According to the
illustrated main and auxiliary diesel engine cooling water systems diagram,
which of the following heat exchangers are connected directly in series
with one another? Illustration MO-0129 |
Camshaft lube
oil cooler and jacket water cooler |
Jacket water cooler
and scavenge air coolers(s) |
Lube oil cooler
and jacket water cooler |
Camshaft lube
oil cooler and scavenge air coolers(s) |
|
B |
Sacrificial zinc
anodes are used on the saltwater side of diesel engine heat exchangers to
__________. |
keep heat transfer
surfaces shiny and clean |
reduce electrolytic
action on heat exchanger metals |
prevent rapid
accumulation of marine growth |
provide a protective
coating on heat exchanger surfaces |
|
A |
In a diesel engine
jacket water cooler, with sea water cooling the fresh water, the __________. |
jacket water pressure
should always be greater than the sea water pressure |
jacket water pressure
must always be less than the sea water pressure |
jacket water temperature
must always be less than 60°F |
sea water temperature
must never be warmer than 40°F |
|
A |
When checking
zincs in a saltwater cooled heat exchanger, you should __________. |
replace the zincs
if they are approximately 50% consumed |
paint the zincs
to stop corrosion |
file the zincs
to change the shape |
insulate the zincs
to alter the temperature |
|
A |
In a diesel engine
lube oil cooler, with sea water cooling the lubricating oil, what statement
is true? |
The lube oil pressure
is always kept higher than the sea water pressure, and in case of a lube
oil cooler leak, the lube oil sump level will decrease. |
The sea water
pressure is always kept higher than the lube oil pressure, and in case of
a lube oil cooler leak, the lube oil sump level will increase. |
The sea water
pressure is always kept higher than the lube oil pressure, and in case of
a lube oil cooler leak, the lube oil sump level will decrease. |
The lube oil pressure
is always kept higher than the sea water pressure, and in case of a lube
oil cooler leak, the lube oil sump level will increase. |
|
A |
in a diesel engine
jacket water cooler, with sea water cooling the engine jacket cooling water,
what statement is true? |
The jacket water
pressure is always kept higher than the sea water pressure, and in case
of a jacket water cooler leak, the jacket water expansion tank level will
increase. |
he sea water pressure
is always kept higher than the jacket water pressure, and in case of a jacket
water cooler leak, the jacket water expansion tank level will increase. |
The jacket water
pressure is always kept higher than the sea water pressure, and in case
of a jacket water cooler leak, the jacket water expansion tank level will
decrease. |
The sea water
pressure is always kept higher than the jacket water pressure, and in case
of a jacket water cooler leak, the jacket water expansion tank level will
decrease. |
|
B |
A three-way thermostatic
control valve regulates the diesel engine cooling water temperature by passing
a portion of the water __________. |
overboard |
around the cooler |
to the expansion
tank |
around the engine |
|
A |
What would be
considered a normal temperature increase between the inlet and outlet jacket
cooling water of a medium or high-speed diesel engine operating at normal
load? |
10° to 20°F |
1° to 5°F |
5° to 10°F |
50° to 100°F |
|
B |
An electric heater
built into some smaller diesel engines is used to __________. |
increase air inlet
temperature |
increase jacket
water temperature for easier starting in cold weather |
increase compression
ratio |
raise lube oil
viscosity for easier starting in cold weather |
|
D |
In a diesel engine
closed freshwater cooling system employing a radiator, proper water temperature
can be obtained by __________. |
passing cooling
water through a space heater |
passing cooling
water through the lube oil cooler |
piping exhaust
gases across the radiator front |
adjusting the
radiator louvers |
|
D |
The temperature
at which an adjustable bellows type thermostatic valve operates is determined
by __________. |
changing the position
of the actuating bulb |
varying air loading
pressure to the bellows |
replacing the
bellows with a heavier spring |
changing the spring
compression opposing the bellows |
|
C |
According to the
illustrated diesel engine cooling water systems diagram, what fluid is the
low temperature central fresh water thermostat designed to maintain? Illustration
MO-0129 |
The low temperature
central fresh water return header temperature. |
The low temperature
central fresh water cooler outlet temperature. |
The low temperature
central fresh water supply header temperature. |
The low temperature
central fresh water cooler inlet temperature. |
|
C |
According to the
illustrated diesel engine cooling water systems diagram, what is the functional
description of the low temperature central fresh water thermostat? Illustration
MO-0129 |
The thermostat
is a two-way valve set up to throttle the flow bypassing around the central
fresh water cooler. |
The thermostat
is a two-way valve set up to throttle the flow through the central fresh
water cooler. |
The thermostat
is a three-way valve set up as a mixer proportioning flow through and around
the central fresh water cooler. |
The thermostat
is a three-way valve set up as a diverter proportioning flow through and
around the central fresh water cooler. |
|
B |
If the cooling
water temperature and the lube oil temperature in a diesel engine are too
high, the cause can be __________. |
a dirty lube oil
strainer |
excessive wear
of the cooling water pump |
an oil suction
line restriction |
internal water
leaks |
|
B |
If the raw water
supply pressure for a diesel engine cooling system is below normal, you
should check for a __________. |
cracked head |
clogged sea strainer |
broken thermostat |
blown head gasket |
|
B |
Antifreeze solutions
containing ethylene glycol should not be mixed with corrosion protection
oils, as the resultant mixture __________. |
is dangerously
flammable |
may cause frothing |
has a higher chloride
content |
promotes scale
buildup |
|
D |
In a closed cooling
water system, which of the following problems can cause the water pressure
to fluctuate? |
An open vent in
the cooling system. |
A restricted water
passage in the engine. |
A fouled sea chest. |
Air entrained
in the cooling water. |
|
A |
When a leak has
developed in the lube oil cooler of an operating diesel engine, which of
the listed operating conditions can be expected to occur? |
Lube oil level
decreases |
Lube oil level
increases |
Lube oil contaminated
with fresh water coolant |
Lube oil contaminated
with saltwater |
|
B |
On small diesel
engines, a noticeable decrease in the time interval between the replacement
of the lube filter cartridge indicates __________. |
excessive oil
temperature |
piston ring blow-by |
excessive oil
pressure |
dirty air filter |
|
D |
Scale and dirt
accumulation in the waterside of a lube oil cooler will be indicated by
a gradual increase in the lube oil __________. |
foaming |
viscosity |
TBN number |
temperature |
|
A |
How is the illustrated
strainer element cleaned during engine operation? Illustration MO-0057 |
The T-handle is
rotated. |
The housing is
removed and the element is cleaned with a solvent. |
The drain plug
is removed and the housing is drained. |
The strainer element
is removed, cleaned in kerosene or solvent, and dried with an air brush. |
|
B |
In a normally
operating diesel engine, the main source of lubricating oil contamination
in the crankcase is a result of the __________. |
air when no air
cleaners are used |
combustion byproducts
removed from the cylinder walls |
condensation of
water vapors |
metal particles
loosened by wear |
|
D |
A dirty diesel
engine oil filter element can best be detected by __________. |
visual inspection
of the elements |
high lube oil
sump temperature |
decrease in oil
viscosity from the filter |
the pressure drop
across the filter |
|
B |
The color of the
diesel engine detergent type lube oil in an operating diesel engine is black,
this indicates __________. |
water dilution |
normal oil condition |
fuel dilution |
worn out' oil |
|
C |
A dirty lube oil
strainer can result in __________. |
crankcase dilution |
low lube oil temperature |
low bearing oil
pressure |
excessive oil
consumption |
|
B |
In an operating
diesel engine, pre-ignition can be caused by __________. |
excessively late
fuel injection |
oil in the air
charge |
water in the fuel |
injection continuing
after the fuel charge is ignited |
|
D |
Irregular engine
speed in a diesel generator can be caused by __________. |
high generator
load |
low fuel viscosity |
high injection
pressure |
binding in the
fuel control linkage |
|
B |
If fuel oil were
being discharged from the waste water outlet of a fuel oil disk type centrifuge,
operated as a separator, you should __________. |
remove the discharge
ring |
reprime the purifier
with sealing water |
slow the centrifuge
to its proper speed |
install an additional
discharge ring |
|
D |
A modern centrifuge,
similar to the device shown in the illustration, is opened for periodic
cleaning. The most common cause of operating failure after reassembling,
is due to __________. Illustration MO-0012 |
low drive motor
RPM |
excessive back
pressure in the bowl and fuel oil break over |
the failure of
the opening and closing water supply |
not replacing
the bowl O-rings that have taken a permanent set |
|
B |
Heat damage to
fuel injection nozzles can be prevented by avoiding __________. |
excessive fuel
oil temperature |
long periods of
engine overload |
metallic contact
between nozzles and cylinder heads |
hard carbon deposit
and varnish on the nozzles |
|
A |
One cause of diesel
engine surging can be a result of __________. |
injection pump
fuel rack binding or sticking |
low compression |
solenoid stuck
open |
fuel booster pump
pressure too high |
|
A |
Which of the following
problems can occur if you continually fail to drain off condensate from
a starting air receiver? |
Corrosion and
eventual failure of the tank. |
Gumming of the
tank relief valves. |
Immediate failure
of components downstream of the compressed air system. |
Boiling of the
water oil mixture as pressure is reduced. |
|
A |
On a diesel engine
with direct-cylinder admission air starting, a leaking air starting valve
would be indicated by __________. |
an overheated
starting air supply pipe |
excessive smoke
from the engine exhaust |
carbon deposit
on the exhaust valves |
early fuel ignition |
|
B |
Which of the following
conditions is most likely to occur if the electric starter motor pinion
gear fails to disengage from the flywheel of a diesel engine after the engine
has started? |
Engine will stop |
Starting motor
will dangerously over speed |
Flywheel will
be damaged |
Combustion gases
will enter the air starting system |
|
C |
When starting
air is admitted, a diesel engine turns over very slowly without firing.
The cause may be __________. |
an obstruction
in an engine cylinder |
water accumulation
in some engine cylinders |
low starting air
pressure |
low scavenge air
pressure |
|
B |
When an additional
load is applied to a diesel engine which is using an inadequately inflated
air bladder clutch unit, you can expect __________. |
pneumatic seizure |
overheating because
of slipping shoes |
chipped reduction
gear teeth |
excessive wear
on the thrust bearings |
|
B |
Misalignment of
the drive shaft and propeller shaft flanges can be detected by using a dial
indicator or __________. |
inside micrometer |
feeler gage |
adjustable trammel |
sighting device |
|
B |
One of the most
common causes of reduction gear failure is gear wear caused by scoring as
a result of __________. |
surface fatigue
of the gears |
an inadequate
lube oil film |
plastic flow of
the gears |
fretting corrosion
from water contamination |
|
A |
In a diesel engine,
a leaking exhaust valve can cause __________. |
misfiring |
preignition |
interrupted scavenging |
reduced scavenging |
|
B |
A dry-type exhaust
silencer clogged with soot, will cause __________. |
low exhaust temperature |
loss of engine
power |
burned intake
valves |
engine racing |
|
D |
White smoke exhausting
from a diesel engine can result from __________. |
high exhaust temperature |
high lube oil
temperature |
low turbocharger
speed |
low cooling water
temperature |
|
C |
Black smoke exhausting
from an operating diesel engine is an indication of poor combustion which
may be caused by __________. |
water in the fuel |
insufficient fuel
for combustion |
clogged air intake
passages |
burning lubricating
oil |
|
A |
A diesel engine
may be hard to start if the __________. |
air intake is
restricted |
engine is cranked
too fast |
vibration dampener
is faulty |
exhaust back pressure
is low |
|
B |
Which of the following
conditions is indicated by the presence of water in the scavenging air receiver? |
Leaking cylinder
head gaskets |
Leaking after
cooler
|
Excessively high
scavenge air temperature
|
Auxiliary blower
failure |
|
D |
Excessive mechanical
and pulsating vibrations developed in a main propulsion diesel engine may
be more likely to cause damage to an attached __________. |
scavenged air
pump because it is designed for steady state operation rather than pulsating
gas load
|
reciprocating
scavenge pump because of its direct linkage to the crankshaft
|
centrifugal cooling
water pump because of the close tolerances required between the impeller
rim and the volute |
gas driven turbocharger
because it has a wide speed range, high operating temperatures and close
tolerances. |
|
C |
Maintaining the
lowest possible scavenging air temperature at all times is not recommended
due to the possibility of the __________. |
air charge density
becoming too high |
piston crown surfaces
becoming too cold |
formation of excessive
quantities of condensate |
compression pressure
being greatly reduced |
|
C |
The power output
of a turbo-charged diesel engine will drop if the cooling water flow through
the after cooler is interrupted because the __________. |
turbocharger stalls |
exhaust pressure
increases |
air charge density
decreases |
scavenge effect
increases |
|
D |
Which condition
indicates the air side fouling of an aftercooler on a turbocharged diesel
engine? |
An increased air
temperature differential between the cooler inlet and outlet. |
A decrease in
the air pressure differential across the cooler. |
Excessive condensate
forming in the air box. |
A decrease in
the air temperature differential between the cooler inlet and outlet. |
|
C |
Which of the following
problems can cause an above normal air temperature to develop in the intake
manifold of a turbocharged and after cooled diesel engine? |
Faulty turbocharger
turbine diffuser ring |
Faulty turbocharger
compressor ring |
Insufficient cooling
water flow to the after coolers |
Clogged air intake
filters |
|
A |
An operating diesel
engine that suddenly loses power, is due to a/an __________. |
restricted turbocharger
air intake |
oil leak into
the turbocharger |
dribbling injector |
low fuel viscosity |
|
D |
Corrosion and
grooving on the blading of an exhaust driven turbocharger is caused by certain
components of residual fuel oils. These components are vanadium, sodium,
and __________. |
copper |
carbon |
hydrogen |
sulfur |
|
A |
A sudden power
loss from a turbocharged and aftercooled diesel engine is an indication
of a/an __________. |
turbocharger malfunction
or failure |
crankcase exhauster
overload |
overload on the
intercooler |
obstruction in
the engine cylinders |
|
D |
A thin film of
oil on the lobes of a Roots-type blower indicates __________. |
proper lubrication
|
timing out of
adjustment |
excessive cylinder
lubrication |
leaking rotor
bearing oil seals |
|
C |
The theoretical
minimum compression ratio necessary to ensure compression ignition in a
direct injection diesel engine is __________. |
18:1 |
10:1 |
12:1 |
8:1 |
|
D |
If the compression
ratio is increased on any diesel engine, __________. |
the expansion
ratio will decrease |
combustion will
be slowed down |
thermal efficiency
will decrease |
thermal efficiency
will increase |
|
B |
The most important
factor in engine performance is the actual power output at the end of the
crankshaft available for doing work. This is known as __________. |
indicated horsepower |
brake horsepower |
net horsepower |
friction horsepower |
|
A |
Which of the following
relationships exist between the temperature developed in a combustion space,
and the compression ratio of the engine? |
Higher compression
ratios create higher temperatures. |
Higher temperatures
create higher compression ratios. |
Lower temperatures
create higher compression ratios. |
Higher compression
ratios create lower temperatures. |
|
B |
Which of the following
reasons represents why the designed compression ratio of a gasoline engine
is lower than that of a diesel engine? |
Compression must
be low for smooth operation. |
The heat of compression
is not used as an ignition source of the fuel. |
Compression must
be low to have effective preignition. |
Compression must
be low for effective spark ignition. |
|
B |
In the starting
process of a diesel engine, the main object is to attain the compression
conditions sufficient to __________. |
turn the flywheel |
ignite the fuel |
reduce friction |
overcome inertia |
|
A |
The thermal energy
produced by an internal combustion engine is transformed into __________. |
mechanical energy |
external energy |
internal energy |
combustion energy |
|
C |
Diesel engines
are classified as reciprocating internal combustion engines because they
__________. |
burn fuel in a
combustion chamber that moves back and forth |
use a continuous
combustion process to impart rotary motion to the Pistons |
burn fuel in a
closed chamber which imparts linear motion to Pistons |
use energy from
fuel burned outside their cylinders |
|
C |
The highest pressure
in a diesel engine cylinder normally occurs __________. |
at TDC |
before TDC |
after TDC |
during air starting |
|
A |
The load is always
placed on the lower half of the main bearings in a/an __________. |
two-stroke/cycle
engine |
four-stroke/cycle
engine |
reverse cycle
engine |
double acting
engine |
|
B |
Which of the terms
listed below represents the operational speed at which excessive engine
vibration is created? |
Non-harmonic speed. |
Critical speed. |
Maximum speed. |
Design maximum
speed. |
|
D |
The cubic inch
(or liter) displacement of a cylinder is determined by the diameter of the
piston and the __________. |
length of the
crankshaft |
volume of the
clearance space |
weight of the
piston |
length of the
stroke |
|
C |
Which of the following
is an example of a solid bearing? |
Turbo-generator
turbine bearing |
Thrust bearing |
Piston pin bushing |
Spring bearing |
|
C |
The proper location
for journal bearing oil grooves is __________. |
halfway between
bottom and where shells meet |
at the bottom
of the bearing |
as a side relief
where the two shells meet |
in the region
of the load bearing surface |
|
B |
Which of the bearings
listed below is most widely used for the main and connecting rod bearings
of a modern high-speed diesel engine? |
Poured Babbitt,
self-aligning |
Precision insert |
Steel-lined |
Split roller |
|
C |
The linear motion
of a diesel engine piston is converted into the rotary motion required to
drive gears, propeller shafts, and generators by the __________. |
journal bearings |
camshaft |
crankshaft |
flywheel |
|
D |
Connecting rods
in a diesel engine are used to connect the __________. |
crankshaft to
the gear train |
rocker arm to
the camshaft |
engine to the
bed |
piston to the
crankshaft |
|
D |
Component 'U'
of the diesel engine shown in the illustration is called the __________.
Illustration MO-0122 |
frame stiffener |
main bearing support
assembly |
frequency tuner |
crankshaft counterweight |
|
C |
The diesel engine
component labeled "3", shown in the illustration is called the
__________. Illustration MO-0122 |
scavenging air
space |
cylinder liner |
cylinder head |
head valve assembly |
|
B |
In the illustrated
diesel engine, which label points to the piston? Illustration MO-0122 |
6 |
4 |
3 |
K |
|
B |
The diesel engine
wrist pin in the illustration is indicated by the component labeled __________.
Illustration MO-0122 |
"G" |
"7" |
"17" |
"S" |
|
B |
A normally operating
diesel engine is shutdown by __________. |
over speeding
the engine |
securing the fuel
supply |
shutting off the
air supply |
securing the ignition
system |
|
B |
Before starting
a diesel engine, you should always __________. |
clean the air
filter |
check the crankcase
oil level |
change the fuel
oil strainers |
check the pyrometer
readings |
|
A |
Which of the listed
diesel engine operating conditions should be checked immediately after any
diesel engine is started? |
Lube oil pressure |
Exhaust temperature |
Lube oil level |
Water level in
the expansion tank |
|
D |
When attempting
to restart a warm high-speed engine, which of the following reactions can
you expect? |
Excessive fuel
use |
Higher than normal
lube oil pressure |
Longer starting
periods |
Higher than normal
temperatures for start up |
|
B |
Before starting
a diesel engine that has an engine driven lube oil pump, you should __________. |
top off the expansion
tank |
pressurize the
lube oil system with the pre-lube pump |
open the bypass
line |
cut in the lube
oil cooler |
|
A |
Babbitt is a metal
alloy commonly used for lining __________. |
precision bearings |
shim stock |
valve seats |
saltwater piping |
|
c |
When checking
a water-lubricated stern tube bearing while underway, what should be checked
for? |
Ensure that the
stuffing box packing gland is loose enough so that the last ring of packing
is visible. |
Ensure that the
stuffing box packing gland is tight enough so that there is no leakoff
whatsoever. |
Ensure that the
stuffing box packing gland is taken up just enough so that the leakoff rate
is a periodic drip. |
Ensure that the
stuffing box packing gland is loose enough so that there is a steady stream
of water leaking by. |
|
B |
Which of the following
methods is used to securely fasten the Babbitt lining of a reduction gear
bearing to its shell? |
The Babbitt has
a crescent shaped pocket cast symmetrically about the bearing split. |
The Babbitt is
centrifugally spun into the bearings or cast under a pressure head. |
The Babbitt is
securely bonded to the shell by the pressure of the hydrodynamic oil wedge. |
The Babbitt is
relieved in way of the split and held in place by locking pins. |
|
D |
As found in a
reduction gear drive system, thrust bearings serve to __________. |
hold the main
engine in place |
increase the shaft
speed |
limit the radial
movement of the shaft |
transmit the force
produced by the propeller to the structure of the ship |
|
B |
By what means
are two sections of propulsion line shafting typically joined together? |
By the use of
a sleeve or clamp type solid coupling |
By the use of
a flange type solid coupling |
By the use of
a chain type flexible coupling |
By the use of
a gear type flexible coupling |
|
B |
In addition to
checking the lube oil sump level and temperature of a line shaft steady
bearing, what else must be checked for? |
Ensure flow through
the gravity head tank overflow sight glass. |
Ensure free rotation
of the oiling ring with the shaft. |
Ensure that the
oiling ring does not rotate with the shaft. |
Ensure adequate
lube oil pump discharge pressure. |
|
C |
What is the primary
purpose of self-aligning spherically-seated line shaft bearings? |
To compensate
for torsional twisting of the shaft in response to torque variations. |
To compensate
for variations in propeller thrust loading in response to load changes. |
To compensate
for flexing of the hull in response to different loading conditions. |
To compensate
for propeller induced vibrations as a result of propeller irregularities. |
|
D |
What statement
is true concerning oil-lubricated stern tube bearings? |
The forward and
after seals are both designed to prevent the ingress of sea water and the
after seal is designed to retain the lubricating oil within the bearing. |
The forward and
after seals are both designed to prevent the ingress of sea water and the
forward seal is designed to retain the lubricating oil within the bearing. |
The forward and
after seals are both designed to retain the lubricating oil within the bearings
and the forward seal is designed to prevent the ingress of sea water. |
The forward and
after seals are both designed to retain the lubricating oil within the bearings
and the after seal is designed to prevent the ingress of sea water. |
|
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 |
|
A |
Hydraulic couplings
will transmit torque equal to the input torque by means of energy changes
in a rotating vortex of liquid. For the vortices to form there must be __________. |
slip between the
impeller and runner
|
less than 2 per
cent slip between the impeller and runner
|
axial thrust generated
by the runner pinion shaft
|
momentary torsional
vibration transmitted by the driving impeller |
|
C |
The pinion gear
shown in the illustration, is located __________. Illustration MO-0086 |
below "2"
and "4" |
between "2"
and "4" |
between "1"
and "3" |
below "1"
and "3" |
|
A |
One advantage
of electromagnetic slip couplings is __________. |
torsional vibrations
are reduced
|
torque increases
with a decrease in excitation current
|
the coupling rapidly
responds to sudden changes of load
|
excitation and
induction power losses appear as a change in torque instead of rotational
speed between the primary and secondary elements |
|
A |
What type of clutch
is used in the illustrated medium-speed diesel engine reduction gear? Illustration
MO-0085 |
Pneumatic |
Mechanical |
Electromagnetic |
Hydraulic |
|
B |
What type of clutch
is pictured in the illustration? Illustration MO-0089 |
Mechanical |
Hydraulic |
Electromagnetic |
Pneumatic |
|
A |
Which of the following
methods is used to lubricate main propulsion medium-speed diesel engine
reduction gears? |
Oil is sprayed
through nozzles at the point of gear mesh. |
Oil rings in channels
outside the gears dip into oil in the sump and carry it to the gear teeth. |
The gears run
through an open oil sump and oil is carried along on the gear teeth. |
Oil is pressure
fed through internal drilled passages which force oil to the gear's periphery. |
|
C |
The purpose of
the main diesel engine reduction gears is to __________. |
transmit vibration
and thrust to the ship's hull |
provide a means
of reversing the main diesel engines in an emergency |
reduce high diesel
engine RPM to an efficient propeller RPM |
reduce engine
room noise levels during high-speed operations |
|
B |
The component
shown in the illustration, labeled "I", is the __________. Illustration
SE-0013 |
first reduction
pinion |
first reduction
gear |
second reduction
gear |
second reduction
pinion |
|
C |
What type of reduction
gear would most commonly be used with twin medium-speed propulsion diesel
engines driving a single shaft? |
Single reduction,
planetary |
Single reduction,
single input |
Single reduction,
double input
o |
Double reduction,
double input, articulated |
|
B |
Reduction gear
casings are vented in order to __________. |
allow windage
to exist for cooling the gears |
avoid a buildup
of pressure within the gear case
|
minimize lube
oil foaming within the case
|
allow for axial
clearance between the gears |
|
B |
In addition to
achieving a speed reduction for efficient propeller operation, what statement
represents other possible functional purposes for reduction gears? |
Reduction gears
can be used for engine rotation reversal and reduction gears can be used
for multiple propeller shaft outputs. |
Reduction gears
can be used for propeller thrust reversal and reduction gears can be used
for multiple prime mover inputs. |
Reduction gears
can be used for propeller thrust reversal and reduction gears can be used
for
multiple propeller shaft outputs. |
Reduction gears
can be used for engine rotation reversal and reduction gears can be used
for
multiple prime mover inputs. |
|
D |
What would be
the most accurate description of the illustrated cutaway drawing of a reduction
gear as used for medium-speed diesel propulsion? Illustration MO-0085 |
Single input,
single reduction, non-reversing gear |
Single input,
double reduction, non-reversing gear |
Single input,
double reduction, reversing gear |
Single input,
single reduction, reversing gear |
|
A |
Which of the statements
represents a characteristic of the thrust collar in a Kingsbury thrust bearing? |
It turns with
the shaft and the pivot shoes do not rotate.
|
It is stationary
and the shoes turn with the shaft.
|
It is turned by
the base ring of the bearing.
|
It is held in
position by the bearing base ring. |
|
A |
The bearing shown
in the illustration is designed to carry thrust when applied __________.
Illustration MO-0001 |
right to left
only |
the bearing pictured
is not designed to carry thrust |
in either direction |
left to right
only |
|
B |
What is the function
of the main thrust bearing? |
Prevents lateral
movement of the slow speed gear. |
Transmits propeller
thrust to the hull. |
Keeps spring bearings
in line. |
Prevents main
reduction gear axial movement. |
|
A |
Kingsbury thrust
bearings are lubricated by __________. |
flooding the thrust
bearing assembly with oil |
submerging oil
wiper rings in an oil bath |
pressure lubricating
through internal passages |
spraying oil directly
on the thrust collar and shoes |
|
B |
On a large diesel
engine installation, crankshaft axial alignment is maintained by the __________. |
piston rod guides |
engine thrust
bearing |
crosshead bearing |
main shaft flexible
coupling |
|
C |
With a direct
drive main propulsion arrangement, what statement is true? |
The engine to
propeller shaft speed ratio is variable. |
The engine speed
is greater than the propeller shaft speed. |
The engine speed
is equal to the propeller shaft speed. |
The engine speed
is lower than the propeller shaft speed. |
|
C |
When a slow-speed
diesel engine is used to directly drive a fixed-pitch propeller, how is
a stop order met? |
Both the ahead
and astern clutches must be disengaged. |
The propulsion
clutch must be disengaged. |
The engine itself
must be stopped. |
The propeller must be brought
to zero pitch. |
|
C |
What type of propeller
thrust reversing method (or methods) is or are used with a main propulsion
slow-speed crosshead type diesel engine installation? |
A non-reversing
engine driving a fixed-pitch propeller is the only method used. |
A reversing engine
driving a controllable-pitch propeller is the only method used. |
Either a reversible
engine driving a fixed-pitch propeller or a non-reversible engine driving
a controllable-pitch propeller could be used. |
Either a reversible engine
driving a controllable-pitch propeller or a non-reversible engine driving
a fixed-pitch propeller could be used. |
|
D |
Diesel engines
powering large vessels that drive fixed-pitch propellers through a nonreversing
reduction gear are of what type? |
Medium-speed,
non-reversing engines |
Slow-speed, reversing
engines |
Slow-speed, non-reversing
engines |
Medium-speed, reversing engines |
|
D |
Fuel is admitted
to a diesel engine cylinder through the __________. |
intake valves |
carburetor |
exhaust ports |
injector nozzles |
|
C |
Fuel injection
systems are designed to primarily meter fuel, atomize fuel, and __________. |
create turbulence
in the combustion chamber |
aid in completing
cylinder scavenging |
inject fuel at
the proper time |
minimize fuel
penetration into the cylinder |
|
D |
Movement of the
pump control rack in a fuel injection system using individual plunger-type
pumps __________. |
varies the compression
of the delivery valve spring |
changes the length
of the pump stroke |
changes the position
of the fuel inlet ports |
varies the quantity
of fuel delivered |
|
B |
Fuel oil discharged
into the diesel engine cylinder is atomized at the __________. |
turbocharger |
injector nozzle
tip |
carburetor |
fuel oil pump |
|
B |
The illustrated
device is operated directly by __________. Illustration MO-0041 |
a rocker arm and
push rod |
fuel oil pressure |
cam action |
excessively high
combustion pressure |
|
A |
The main advantage
of unit injectors over other fuel injection systems is __________. |
the lack of high
pressure fuel lines |
their relatively
low injection pressures |
reduced wear of
spray orifices |
the lessened chance
of fuel leaks into the engine sump |
|
D |
Injection pressure
in a common rail fuel system is controlled by __________. |
engine speed |
varying the fuel
pump piston stroke |
varying the injector
needle valve clearance |
a bypass valve |
|
B |
Fuel injection
pumps using the port and helix metering principle requires the use of a
__________. |
crosshatched design |
lapped plunger
and barrel |
variable stroke |
variable cam lift |
|
C |
Which of the fuel
injection systems listed uses a spring loaded differential spray needle
valve and an individual pump for each cylinder? |
Common-rail injection |
Air injection |
Jerk pump injection |
Distributor injection |
|
C |
The amount of
fuel delivered by a helical plunger fuel injection pump is controlled by
__________. |
varying the pump
discharge pressure |
varying the pump
return pressure |
rotation of the
pump plunger |
rotation of the
pump barrel |
|
A |
In what location
is heavy fuel oil kept below the flash point? |
Heavy fuel oil
settling and day tanks |
Heavy fuel oil mixing tank |
Heavy fuel oil
purifier heater outlet |
Heavy fuel oil
final heater outlet |
|
C |
In what location
is heavy fuel oil kept above the flash point, but below the boiling point
of water? |
Heavy fuel oil
settling and day tanks |
Heavy fuel oil
mixing tank |
Heavy fuel oil
final heater outlet |
Heavy fuel oil
purifier heater outlet |
|
C |
In an HFO service
system, what is the immediate destination of the fuel unconsumed by the
main propulsion diesel engine? |
The unconsumed
fuel is recirculated back to the fuel injection pumps suction. |
The unconsumed
fuel is recirculated back to the settling tank. |
The unconsumed
fuel is recirculated back to the mixing tank (if fitted) or to the day tank. |
The unconsumed
fuel is recirculated back to the booster pump suction. |
|
A |
Which of the listed
substances can be satisfactorily removed from diesel fuel by centrifuging? |
Sludge |
Gasoline |
Fuel oil |
Lube oil |
|
B |
Whether using
a centrifuge or a simple filter, oil cleaning and filtration will be the
most effective when the oil is at a __________. |
high temperature
and a high viscosity |
high temperature
and a low viscosity |
low temperature
and a high viscosity |
low temperature
and a low viscosity |
|
B |
When monitoring
a heavy fuel oil treatment plant, what would be an indication that the treatment
plant throughput volume is less than the main engine consumption? |
The HFO settling
tank will continuously drop in level. |
The HFO day tank
will continuously drop in level. |
The HFO day tank
will rise and eventually overflow into the HFO settling tank. |
The HFO settling
tank will rise and eventually overflow into the HFO day tank. |
|
D |
According to the
illustrated diesel engine fuel treatment and fuel service systems schematic,
what would be the appropriate valve configuration for operating the two
heavy fuel oil purifiers in series? Illustration MO-0077 |
Valves 2, 3, and
6 all OPEN |
Valves 2, 3, and
6 all CLOSED |
Valves 2 and 3
OPEN, and Valve 6 CLOSED |
Valves 2 and 3
CLOSED, and Valve 6 OPEN |
|
A |
According to the
illustrated diesel engine fuel treatment and fuel service systems schematic,
what statement is true concerning the valves labeled "4" and "5"?
Illustration MO-0077 |
Valves 4 and 5
are closed during normal operation, but when opened will allow one of the
HFO purifiers to be used as a backup DO purifier, should the DO purifier
become disabled. |
Valves 4 and 5
are closed during normal operation, but when opened will allow the DO purifier
to be used as a backup HFO purifier, should one of the HFO purifiers become
disabled. |
Valves 4 and 5
are closed during normal operation, but when opened will allow all three
purifiers to centrifuge HFO while in series. |
Valves 4 and 5
are closed during normal operation, but when opened will allow all three
purifiers to centrifuge HFO while in parallel. |
|
A |
Valve '1', as
shown in the illustration when, should be operated when __________. Illustration
MO-0077 |
entering or departing
port. |
starting auxiliary
boilers. |
viscosimeter 'V'
measures low viscosity. |
mixing tank is
'full'. |
|
D |
To minimize corrosion,
fuel oil strainer disks, spacers and scraper blades are made of __________. |
brass |
copper |
iron |
monel metal or
stainless steel |
|
A |
For a continuous
operation diesel engine, a duplex filter unit would be the best arrangement
because __________. |
changing filter
elements would not interrupt engine operation |
filtering occurs
twice in each pass of oil through the system |
clogging will
not occur |
dropping pressure
is half of that through a single filter unit |
|
C |
According to the
illustrated diesel engine fuel treatment and fuel service systems schematic,
what is the purpose of the valve labeled "1"? Illustration MO-0077 |
HFO/DO fuel mixing
valve for main engine |
HFO/DO fuel changeover
valve for auxiliary engines (and boiler) |
HFO/DO fuel changeover
valve for main engine |
HFO/DO fuel mixing
valve for auxiliary engines (and boiler) |
|
B |
What would be
the primary indication that a heavy fuel oil purifier supply pump suction
strainer needed cleaning? |
An increase in
fuel oil supply temperature to the bowl. |
An increased pressure
drop across the strainer (more differential). |
A decreased pressure
drop across the strainer (less differential). |
A drop in purifier
bowl speed. |
|
B |
What would be
the primary indication that a fuel oil service system booster pump duplex
suction strainer needed to be shifted over and cleaned? |
A decreased pressure
drop across the strainer element on service (less differential). |
An increased pressure
drop across the strainer on service (more differential). |
A drop in fuel
oil service system booster pump rotational speed. |
An increase in
fuel oil service system booster pump discharge pressure. |
|
D |
Cooling the intake
air supplied to a diesel engine will __________. |
reduce mean effective
pressure |
decrease average
compression ratio |
decrease air charge
density |
increase peak
power output |
|
C |
A large, low-speed,
main propulsion diesel engine uses sea water to directly cool the __________. |
cylinder heads |
exhaust valves |
scavenging air |
injectors |
|
C |
An increase in
the air inlet manifold pressure of a diesel engine will result in a/an __________. |
decrease in maximum
cylinder pressure |
increase in ignition
lag |
decrease in fuel
consumption per horsepower-hour |
decrease in exhaust
manifold pressure |
|
B |
In a naturally
aspirated diesel engine, the volume of air intake is directly associated
with engine __________. |
compression ratio |
displacement |
fuel pressure |
cylinder clearance
volume |
|
C |
What is the function
of the intake system for a diesel engine? |
The intake system's
function is to ensure an adequate supply of clean lubricating oil to support
engine lubrication. |
The intake system's
function is to ensure an adequate supply of clean sea water to support engine
cooling. |
The intake system's
function is to ensure an adequate supply of clean air to support engine
combustion and scavenging. |
The intake system's
function is to ensure an adequate supply of clean air to support engine
crankcase ventilation. |
|
D |
What is the function
of the after coolers installed in the diesel engine air intake system? |
Decrease the air
density |
Increase the exhaust
temperature |
Decrease the lube
oil temperature |
Increase the air
density |
|
C |
The section of
the turbocharger which would be connected to the aftercooler inlet is labeled
__________. Illustration MO-0080 |
C |
H |
B |
K |
|
A |
Compared to a
naturally aspirated diesel engine, a supercharged diesel engine has __________. |
a cylinder air
charge of higher pressure |
reduced cylinder
mean effective pressure |
less valve overlap |
reduced blow-by |
|
A |
A naturally aspirated
diesel engine at full throttle will have an intake manifold pressure __________. |
slightly less
than atmospheric pressure |
approximately
equal to exhaust manifold pressure at all times |
that is widely
fluctuating |
constantly decreasing
as engine load increases |
|
D |
The most common
instrument used to measure diesel engine exhaust pressure is the __________. |
pyrometer |
bourdon gauge |
pneumercator |
manometer |
|
B |
In a diesel engine
exhaust system, the cooling of the exhaust gases below their dew point,
will result in __________. |
increased engine
back pressure |
sulfuric acid
corrosion |
surface pitting
of the turbocharger compressor blades |
moisture impingement
on the turbocharger compressor blading |
|
B |
One of the factors
limiting the amount of load which can be put on a modern marine diesel engine
is the __________. |
governor sensitivity |
exhaust temperature |
fuel injection
pressure |
speed of the cam
shaft |
|
C |
Exhaust pipes
for separate main propulsion diesel engines can be combined only when __________. |
space limitations
prevent separately run pipes |
the engines are
small auxiliary units |
they are arranged
to prevent gas backflow to each engine |
a waste heat boiler
is installed |
|
B |
The exhaust system
for a turbocharged diesel engine functions to __________. |
power the after
coolers |
power the turbocharger |
reduce the cylinder
scavenge effect |
cool the turbocharger |
|
D |
The lube oil strainer
shown in the illustration is used on the reduction gear of a mid-size diesel
engine. The strainer elements consist of __________. Illustration MO-0057 |
fibrous braid |
wire mesh |
pleated paper |
metal disks |
|
D |
Lube oil cannot
be efficiently filtered if it's __________. |
pump capacity
is greater than the system's needs |
viscosity is too
low |
pump discharge
pressure is higher than the system's pressure |
temperature is
too low |
|
A |
A magnetic strainer
is primarily used in diesel engine reduction gear oil systems to remove
small particles of __________. |
ferrous materials |
Babbitt |
copper |
acidic materials |
|
A |
Where would a
coarse screen wire-mesh strainer normally be found on a diesel engine lubrication
system? |
pump suction line |
filter bypass
return line |
pump discharge
line |
gravity tank inlet
line |
|
A |
Which of the following
statements is true concerning a main diesel engine oil cooler? |
The oil pressure
is greater than the cooling water pressure. |
The oil flow control
valve is always installed in the oil input line. |
The oil temperature
is less than the cooling water temperature. |
The oil pressure
is less than the cooling water pressure. |
|
A |
The lube oil cooler
is located after the lube oil filter in order for __________. |
the filter to
operate more efficiently |
galvanic action
in the cooler to be minimized |
positive lube
oil pump suction to be assured |
the lube oil cooler
to be bypassed |
|
A |
Heat exchangers
are most commonly found in a small auxiliary diesel engine __________. |
lube oil system |
governing system |
air starting system |
fuel oil system |
|
A |
The purpose of
an oil mist detector in a main propulsion diesel engine is to warn of __________. |
a possible overheated
bearing |
excessive carbon
buildup in the lube oil |
low cylinder oil
pressure |
excessively high
crankcase vacuum |
|
A |
Which of the following
problems could develop due to the accumulation of oil vapors in the crankcase
of a diesel engine? |
Crankcase explosion |
Poor fuel economy |
Reduced lubrication |
Combustion knock |
|
B |
The possibility
of a diesel engine crankcase explosion will be increased by operating an
engine __________. |
with a crankcase
vacuum between 1.5" and 2" of water |
with a leaking
crankcase inspection cover gasket |
equipped with
a crankcase exhaust blower which vents to fresh air |
in cooler sea
water temperatures |
|
A |
If a diesel engine
has been stopped because of piston seizure due to severe overheating, the
crankcase __________. |
inspection covers
should not be opened until the engine has cooled |
scavenge pump
should be immediately secured to prevent loss of lube oil |
ventilation system
should be continued in operation for one hour for cooling |
explosion covers
should be opened slightly to provide extra ventilation |
|
B |
Which of the following
methods is normally used to lubricate bearings in a small high-speed diesel
engine? |
Splash lubrication |
Pressure lubrication |
Sight feed lubricators |
Mechanical lubricators |
|
B |
In an auxiliary
diesel engine "by-pass type" lubricating oil system, the main
lube oil pump forces __________. |
all of the oil
used by the engine through a filter |
some of the oil
used by the engine through a filter |
some of the oil
used by the engine through a centrifuge |
all of the oil
used by the engine through a centrifuge |
|
D |
Lubrication for
the main reduction gears used with diesel engines is usually supplied by
__________. |
oil from the main
engine sump |
the stern bearing
head tank |
the stern bearing
sump tank |
an independent
lube oil system |
|
D |
Lube oil pumps
taking suction from the sump of most small marine engines are usually __________. |
diaphragm type |
eductor type |
centrifugal type |
positive displacement
type |
|
A |
Which of the routine
maintenance procedures listed is required for starting air receivers? |
Frequent draining
of accumulated moisture. |
Frequent testing
of relief valves. |
A close watch
on temperature to prevent fluctuations in pressure. |
Frequent cleaning
to remove oil and foreign matter. |
|
B |
Starting air check
valves are held firmly on their seats by __________. |
cam rollers on
the camshaft |
spring force |
air pressure on
top of the valve differential piston |
air pressure on
the bottom of the valve differential piston |
|
D |
A two-stroke/cycle
diesel engine requires less starting air than a four-stroke/cycle diesel
engine, of equal displacement, because the two-stroke/cycle diesel engine
__________. |
has little or
no internal friction |
has a lower effective
compression ratio |
operates with
scavenge air under a positive pressure |
operates without
energy absorbing intake and exhaust strokes |
|
B |
Where is the air
charge for an air starting system stored? |
Air compressor |
Pressurized tank |
Distributor assembly |
Cylinder check
valve |
|
D |
An accumulator
used in a hydraulic starting system is generally located between the __________. |
pump and the compressor |
storage tank and
the pump |
starting motor
and the reserve tank |
pump and the starting
motor |
|
C |
For a diesel engine,
approximately how long can an electric starter motor be operated continuously
before damage may begin to occur due to overheating? |
Overheating the
motor cannot occur. |
Not more than
90 seconds |
Not more than
30 seconds |
Not more than
60 seconds |
|
A |
Auxiliary diesel
engine electric starting motors use __________. |
battery power
direct current |
400 cycle per
second motor-generator power |
alternating current
transformers |
low amperage,
high voltage AC power |
|
B |
Diesel engine
electric starting motors generally require heavier duty motors and operate
at higher voltages than comparable starting motors for gasoline engines
due to __________. |
flywheel effect |
higher compression
pressures |
lower starting
temperatures |
higher speed required |
|
A |
Air motors used
for starting some auxiliary diesel engines are generally the type known
as a/an __________. |
vane motors |
accumulator motors |
plunger motors |
gear motors |
|
D |
Hydraulic starters
are installed on many lifeboat diesel engines instead of comparable air
start systems, because __________. |
hydraulic starters
are the least expensive of all starting systems |
the system does
not require high pressure piping |
hydraulic systems
turn diesel engines at higher rates of speed than air starters |
the system can
be manually recharged |
|
B |
When an engine
fitted with a hydraulic starting system starts up, the starter is protected
from the higher speed of the engine by __________. |
the immediate
increase in hydraulic pressure |
the overrunning
clutch |
closing the starting
check valves |
the pivoting of
the shaft from being engaged with the flywheel |
|
A |
The purpose of
the engine-driven hydraulic pump in an auxiliary diesel engine hydraulic
starting system is to __________. |
restore hydraulic
pressure in the accumulator after starting |
engage the starter
motor with the flywheel |
fill the sump
and prevent low level in the system |
bypass the hydraulic
motor when the engine is running |
|
D |
A Bendix drive
starting motor disengages the drive gear from the flywheel by __________. |
applying accumulator
pressure |
spring force |
rotating of the
starting cam |
having the flywheel
impart a torque to the starter pinion |
|
D |
The pinion of
an auxiliary diesel electric starting motor normally engages the flywheel
ring gear by means of a/an __________. |
magnetic type
coupling |
automatic follow-up |
muff coupling
and release |
Bendix drive or
similar mechanism |
|
D |
Auxiliary diesel
engine electric starting motors use __________. |
low amperage,
high voltage AC power |
alternating current
transformers |
400 cycle per
second motor-generator power |
battery power
direct current |
|
C |
Starting systems
for large, direct reversing, main propulsion diesel engines are usually
__________. |
hydraulic starting
motor |
electric starting
motor |
direct air admission |
vane type air
motors |
|
A |
During the starting
of a diesel engine, compression gases are prevented from backing into the
air starting system, shown in the illustration, by the __________. Illustration
MO-0046 |
cylinder air starting
check valves |
high pressure
in the starting air manifold |
air starting control
valve |
individual distribution
valves |
|
C |
When an air started,
four-stroke/cycle diesel engine is being cranked over; the starting air
is admitted to each cylinder during the beginning of its __________. |
intake stroke |
compression stroke |
power stroke |
exhaust stroke |
|
D |
In a medium-speed
marine propulsion engine equipped with direct admission air starting valves,
the cylinders without air starting valves fire first because the __________. |
operation is under
higher compression |
fuel is admitted
only to these cylinders during cranking |
compression is
released during starting by opening the exhaust valve |
cylinders are
not chilled by the expansion of the starting air |
|
B |
Auxiliary boilers
are divided into several classifications, one of which is __________. |
water-tube supercritical
circulation |
water-tube forced
circulation |
fire-tube controlled
circulation |
fire-tube express
circulation |
|
A |
In a coil-type
forced circulation auxiliary water-tube boiler,__________. |
steam demand response
is comparatively rapid |
steam is recirculated
through heating coils in the boiler |
unevaporated feed
water is discharged through the skim tube |
steam demand response
is slow |
|
A |
Which of the following
statements concerning fire-tube boilers is correct? |
Combustion gases
flow through the tubes. |
Flames impinge
on the tubes. |
Combustion occurs
in the tubes. |
Water flows through
the tubes. |
|
D |
Bottom blow valves
are installed on auxiliary water-tube boilers to __________. |
completely drain
the boiler in an emergency |
prevent sludge
from forming in the steam drum |
remove floating
impurities from the boiler water surface |
remove settled
solids from the water drum |
|
A |
The purpose of
try-cocks used on an auxiliary boiler is to __________. |
provide an alternate
means of determining the water level, if the gage glass fails |
provide a means
of adding chemical feed to the boiler water |
provide a means
for blowing down the gage glass |
act as a steam
sentinel valve, if any of the fusible plugs should melt |
|
D |
An exhaust gas
bypass is installed on a waste heat boiler in order to __________. |
bypass exhaust
gas at high loads to prevent excessive back pressure
|
bypass a portion
of the exhaust gas at peak loads for better efficiency |
recycle exhaust
gas to the turbocharger |
minimize moisture
condensation in the boiler gas passages at low loads |
|
B |
The maximum pressure
developed by a waste heat boiler is determined by the main engine exhaust
__________. |
gas composition |
gas temperature
|
pressure
|
timing |
|
D |
Casing drains
may be required on a waste heat boiler gas passage side to __________. |
prevent an accumulation
of boiler water entering gas passages as a result of a pinhole tube leak
o |
as a means to
sample stack gases for testing |
release excess
pressure |
drain off condensation |
|
B |
As shown in the
illustration, the function of component "1" is to __________.
Illustration MO-0128 |
condense excess
steam produced in the boiler |
evaporate circulating
boiler water into saturated steam
|
maintain a water
level in the steam drum
|
generate superheated
steam to operate the turbo generator |
|
D |
As shown in the
illustration, what component would normally be installed at location "D”?
Illustration MO-0128 |
Boiler soot blower
unit
|
Boiler water level
indicator |
Flue gas smoke
indicator |
Oil fired mechanical
burner |
|
A |
Which of the following
statements concerning fire-tube boilers is correct? |
Combustion gases
flow through the tubes. |
Flames impinge
on the tubes. |
Combustion occurs
in the tubes. |
Water flows through
the tubes. |
|
D |
The boiler shown
in the illustration would be classed as __________. Illustration MO-0064 |
forced circulation,
coil-type |
two-pass, water-tube |
two-pass, scotch
marine |
single-pass, fire-tube,
scotch marine |
|
B |
The tube sheets
installed in a fire-tube auxiliary boiler are normally connected by __________. |
girder stays |
fire-tubes and
stay-tubes |
external boiler
plating |
separate crown
sheets |
|
B |
Fusible plugs
are installed in fire-tube boilers to __________. |
provide a means
of draining the boiler |
warn the engineer
of low water level |
cool the crown
sheet at high firing rates |
open the burners'
electrical firing circuits |
|
D |
Constant capacity,
pressure atomizing, fuel burners designed to meet a wide variation in steaming
loads on an auxiliary boiler, are __________. |
automatically
supplied with warmer air on demand |
automatically
supplied with more fuel on demand |
equipped with
standard variable capacity atomize |
cycled on and
off in response to steam demand
|
|
C |
The primary function
of a flame safeguard system, as used on an automatically fired auxiliary
boiler, is to prevent __________. |
accidental dry
firing and overpressure |
uncontrolled fires
in the furnace |
explosions in
the boiler furna |
overheating of
the pressure parts |
|
A |
A photoelectric
cell installed in an automatically fired auxiliary boiler burner management
system __________. |
opens the burner
circuit upon sensing a flame failure |
detects a flame
failure by monitoring radiant heat from glowing refractory |
requires mechanical
linkage to secure the burner fuel supply |
must be bypassed
at low firing rates |
|
D |
The pressuretrol
which is installed on an auxiliary boiler senses steam pressure changes
and __________. |
controls the flow
of feed water to the boiler |
monitors the boiler
high water level |
secures the fires
when a fusible plug burns out |
automatically
regulates the quantity of oil and air flow to the burner |
|
B |
A variable capacity,
pressure atomizing, fuel oil burner functions to __________. |
maintain a constant
fuel temperature |
provide a wide
range of combustion |
provide a constant
fuel return pressure |
maintain smokeless
fuel oil atomization |
|
C |
The solenoid valves
in the fuel oil supply line to an automatically fired auxiliary boiler,
are automatically closed by __________. |
a decrease in
feed temperature |
high furnace air
pressure |
high steam pressure |
low steam pressure |
|
B |
Control of the
fuel oil metering valve in an automatically fired auxiliary boiler is accomplished
by a __________. |
pressure magnifying
device in the steam coil outlet |
steam pressure
sensing device with linkage to the damper air vanes |
metering device
in the air supply line |
signal from the
feed water electrode |
