Contact Phone: 207-629-7004
Hoist Definitions and Terms
Abnormal Operating Conditions - Environmental
conditions that are unfavorable, harmful, or detrimental to or for the operation
of a hoist , such as excessively high or low ambient temperatures, exposure to
weather, corrosive fumes, dust laden or moisture laden atmospheres, and
Anchor Bolt - A bolt used with its head embedded in
masonry or concrete and its threaded part protruding to hold a jib crane in
Anchor Bolt Load - The total amount of force that is
applied to each supporting anchor bolt in a jib crane; usually measured in kips.
ANSI American National Standards Institute
Appointed Assigned specific responsibilities by
the employer or the employers representative.
ASCE Rail - The runway rails on top running cranes
that the bridge travels on.
Automatic Crane A crane which when activated
operates through a preset cycle or cycles.
Auxiliary Hoist A supplemental hoisting unit of
lighter capacity and usually higher speed than provided for the main hoist.
Axial load - The total vertical force applied to the
supporting structure in a jib crane. Formula: Axial load= (overall weight of the
crane) + (design factor x weight of load)
Bay - The space between the building frames measured
parallel to the crest of the building.
Below-the-hook Lifting Devices - Devices that are
not normally reeved onto the hoist rope or chain, such as hook-on buckets,
magnets , grabs, and other supplemental devices used for ease of handling
certain types of loads. The weight of these devices is to be considered part of
the load to be lifted.
Boom - The horizontal beam (track) upon which a
hoist trolley travels. The jib of the jib crane.
Bracket Center - The distance, center line to center
line, between two supporting brackets of a wall mounted jib crane (i.e. the
distance between the two wall mounting points).
Brake - A device for slowing or, stopping motion by
friction or by electrical means.
Brake, Mechanical Load - An automatic type of
friction brake in the hoist that is used for controlling loads in a lowering
direction. This unidirectional device requires torque from the motor or hand
chain wheel to lower a load but does not impose any additional load on the motor
or hand chain wheel when the hoist is lifting a load. A mechanical load brake is
a mechanical control braking means.
Braking Means - A method or device used for stopping
or holding motion of the hoist by friction or power.
Braking Means, Control - A method of controlling
hoist speed by removing energy from the moving body or by imparting energy in
the opposite direction.
Braking Means, Counter-torque (Plugging) - A method
of control by which the power to the motor is reversed to develop torque in the
direction opposite to the rotation of the motor.
Braking Means, Dynamic - A method of controlling
hoist speed by using the motor as a generator, with the energy being dissipated
Braking Means, Eddy Current - A method of
controlling or reducing hoist speed by means of an energy induction load brake.
Braking Means, Mechanical - A method of controlling
or reducing hoist speed by friction.
Braking Means, Pneumatic - A method of controlling
or reducing hoist speed by means of a compressed gas.
Braking Means, Regenerative - A method of
controlling hoist speed in which the electrical energy generated by the motor is
fed back into the power system.
Block Loads - An action that facilitates the removal
of slings or other lifting devices from under the load, accomplished by bringing
the load to rest on wood, metal, or other spacers between the floor and load.
Bridge - The main travelling structure of the crane
which spans the width of the bay. The bridge consists of two end trucks and one
or two bridge girders.
Bridge Girder(s) - The primary horizontal beam of
the crane bridge which supports the trolley and is supported by the end trucks.
Bridge Travel The crane movement in a direction
parallel to the crane runway.
Bridge, Trolley and Lift Speeds - The rate at which
the bridge or trolley travels, or at which the hoist lifts, usually in feet per
minute or FPM.
Building Aisle - A space defined by the length of a
building and the space between building columns.
Bumper [buffer] An energy absorbing device for
reducing the impact when a moving crane or trolley reaches the end of its
permitted travel; or when two moving cranes or trolleys come in contact.
Cab The operators compartment on a crane
Cab Operated Crane A crane controlled by an
operator in a cab located on the bridge or trolley.
Cantilever Gantry Crane A gantry or semi-gantry
crane in which the bridge girders or trusses extend transversely beyond the
crane runway on one or both sides.
Capacity - The maximum weight in tons the crane will
be required to lift.
Chain Guide - A means to guide the hoist load chain
at the load sprocket.
Chain Hoist A hoists used for lower capacity,
lighter duty applications and for projects in which cost is a primary deciding
Clearance The distance from any part of the crane
to a point of nearest obstruction.
Collectors - Contacting devices for collecting
current from the runway conductors. The mainline collectors are mounted on the
bridge to convey electrical current from the runway conductors.
Conductors, bridge The electrical conductors
located along the bridge structure of a crane to provide power to the trolley.
Conductors, runway [main] are the electrical
conductors located along a crane runway to provide power to the crane.
Control Pendant A device that gives an operator
precise control over the motions of the crane.
Controller, spring return a controller which when
released will return automatically to a neutral position.
Counter-Torque A method of control by which the
power to the motor is reversed to develop torque in the opposite direction.
Crane A machine for lifting and lowering a load
and moving it horizontally with the hoisting integral part of the machine.
Cranes whether fixed or mobile are driven manually or by power.
Crane Aisle - The portion of the building aisle in
which the crane operates, defined by the crane span and the continuous length of
the crane runway.
Crane girder(s) See Bridge Girder(s).
Crane Span - The horizontal distance center to
center of the both runway beams.
Deflection - The difference in elevation at the tip
of the boom between an unloaded jib crane and a fully loaded jib crane; usually
measured in inches. Our Jib Crane designs tend to have stricter deflection
criteria than others in the industry.
Designated Person - A person selected or assigned by
the employer or the employer's representative as being competent to perform
Double Girder - An overhead crane consisting of two
end trucks, two bridge girders and the trolley hoist unit. The trolley runs on
rails on top of the bridge girders.
Drag Brake A brake which provides retarding force
without external control.
Drift Point A point on a travel motion controller
which releases the brake while the motor is not energized. This allows for
coasting before the brake is set.
Drum The cylindrical member around which the ropes
are wound for raising or lowering the load.
Dynamic a method of controlling crane motor speeds
when in the overhauling condition to provide a retarding force.
Electrification System - The various parts of the
crane structure that supply and apply electricity to the trolley hoist.
Emergency Stop Switch A manually or automatically
operated electric switch to cut off electric power independently of the regular
Enclosures - The enclosures house all of the
electrical components on the crane.
End Stop - A device to limit the travel of a trolley
or crane bridge. This device normally is attached to a fixed structure and does
not normally have energy absorbing capability.
End Trucks - Located on either side of the span, the
end trucks house the wheels on which the entire crane travels. These wheels ride
on the runway beam allowing access to the entire length of the bay.
Equalizer A device which compensates for unequal
length or stretch or a rope.
Exposed Capable or being contacted inadvertently.
Applied to hazardous objects not adequately guarded or isolated.
Fail-safe A provision designed to automatically
stop or safely control any motion in which a malfunction occurs.
Floor-Operated Crane A crane which is pendant or
nonconductive rope controlled by an operator on the floor or independent
Footwalk - A walkway with handrail, attached to the
bridge or trolley for accessibility purposes.
Foundation - Free Standing jib cranes require that a
special foundation, usually of concrete and steel, be used to support the crane
and prevent the crane from tipping over. Foundation recommendations can be found
in the price pages and in the installation manual.
Gantry Cranes - An overhead crane where the bridge
girder(s) are connected to legs on either side of the span. These legs
eliminate the supporting runway and column system and connect to end trucks
which run on a rail either embedded in, or laid on top of, the floor.
Hand Chain - The chain grasped by a person to apply
force required for the lifting or lowering motion of the hoist.
Hand Chain Wheel - A wheel with formed pockets on
its periphery to allow torque to be transmitted when a force is applied to the
hoist hand chain.
Hand Geared - The operation of the bridge, hoist, or
trolley of a crane by the manual use of chain and gear without electric power.
Height Under Boom (HUB) - The distance from the
floor to the underside of a jib crane's boom. The minimum height under boom
equals the height of the load, plus the maximum distance the load is to be
lifted, plus the headroom required for the hoist, trolley, and attachments.
Hoist - A mechanical unit that is used for lifting
and lowering a load via a hook or lifting attachment.
Hoist Chain The load bearing chain in a hoist.
NOTE: Chain properties do not conform to those shown in
ANSI B30.9-1971, Safety code for slings
Hoist Motion The motion of a crane which raises
and lowers a load.
Holding Brake - A brake that automatically prevents
movement when there is no power.
Hook Height -See Lift Height.
Hot Metal Handling Crane An overhead crane used
for transporting or pouring molten material.
Idler Sprocket - A freely rotating device that
changes the direction of the hoist load chain.
Jib Crane - A crane consisting of a boom which is
supported as a cantilever on a column.
Lift Height - The maximum safe vertical distance
that the hook can travel from the floor
Lifting Devices - See Below-the-hook Lifting Devices
Limit Device - A device that is operated by some
part or motion of a power driven hoist to limit motion.
Limit Switch - A device designed to disconnect the
power automatically at or near the limit of travel for the crane motion.
Load - The total superimposed weight on the hoist
load block or hook.
Load Block - The assembly of hook or shackle,
swivel, bearing, sheaves, sprockets, pins, and frame suspended by the hoisting
rope or load chain. This shall include any appurtenances reeved in the hoisting
rope or load chain.
Load Chain - The load-bearing chain in a hoist.
Load Sprocket - A hoist component that transmits
motion to the load chain. This hoist component is sometimes called load wheel,
load sheave, pocket wheel, or chain wheel.
Load Suspension Parts - The load suspension parts of
the hoist are the means of suspension (hook or lug), the structure or housing
which supports the drum or load sprocket, the drum or load sprocket, the rope or
load chain, the sheaves or sprockets, and the load block or hook.
Magnet An electromagnetic device carried on a
crane hook to pick up loads magnetically
Main Hoist The hoist mechanism provided for
lifting the maximum rated load.
Main Switch A switch controlling the entire power
supply to the crane.
Man Trolley A trolley having an operators cab
Mast - The vertical steel component of a jib crane
which supports the crane. Free Standing jib cranes (including Work Station Jibs)
have a circular pipe for a mast, Wall Cantilever cranes have standard I-beams,
and Mast Type cranes have wide flange beams. Wall Bracket cranes do not have a
Master Switch A switch which dominates the
operation of the contactors, relays or other remotely operated devices.
Mechanical A method of control by friction
Non-running Sheave - A hoist sheave used to equalize
tension in opposite parts of the rope or chain. Because of its slight movement,
it is not termed a running sheave.
Normal Operating Conditions - Conditions during
which a hoist is performing functions within the scope of the original design.
Overhead Crane A crane with a movable bridge
carrying a movable or fixed hoisting mechanism and traveling on an overhead
fixed runway structure.
Overload - Any hoist load greater than the rated
Over-travel Restraint - A device used to prevent the
hoists slack load chain from inadvertently being lowered out of the load
Parts (Lines) - Number of lines of rope or chain
supporting the load block or hook.
Pendant - The pendant gives the operator precise
control over the motions of the crane.
Pendant Station - Controls suspended from the hoist
for operating the unit from the floor.
Power-Operated Crane A crane whose mechanism is
driven by electric, air, hydraulic or internal combustion means.
Power Supply - The electrical service available in
the building for which the crane is being designed.
Power Transmission Parts - Hoist machinery
components including the gears, shafts, clutches couplings, bearings, motors,
Primary Upper-limit Device - The primary upper-limit
device is the first limit device that will be activated to control the upper
limit of travel of the load block when a hoist is equipped with more than one
Pulpit-Operated Crane A crane operated from a
fixed operator station not attached to the crane.
Qualified Person - A person who, by possession of a
recognized degree in an applicable field or a certificate of professional
standing, or who by extensive knowledge, training , and experience, has
successfully demonstrated the ability to solve or resolve problems relating to
the subject matter and work.
Radio Remote Control - The radio control performs
exactly like the pendant but operates using a radio frequency.
Rated load - The maximum load a crane is designed to
Reeving - A system in which a rope or chain travels
around drums, sheaves or sprockets.
Remote Operated Crane - A crane operated by Radio
Roller Chain - A series of alternately assembled
roller links and pin links in which the pins articulate inside the bushings and
the rollers are free to turn on the bushings. Pins and bushings are press fit in
their respective link plates.
Rope A wire rope, unless otherwise specified.
Rotating Axle - An axle which rotates with a wheel.
Running Sheave - A hoist sheave that rotates as the
load block is lifted or lowered.
Runway - The rails beams, brackets, and columns on
which a crane operates.
Runway Conductors - The main conductors mounted on
or parallel to the runway which provide electrical current to the crane.
Runway Rail - The rail supported by the runway beams
on which the bridge travels.
Semi-Gantry Crane A gantry crane with one end of
the bridge rigidly supported on one or more legs that run on a fixed rail or
runway, the other end of the bridge being supported by a truck running on an
elevated rail or runway.
Side Pull - The component of the hoist pull acting
horizontally when the hoist lines are not operated vertically.
Single Girder - An overhead crane consisting of two
end trucks, a single bridge girder and the trolley hoist unit. The trolley runs
on the bottom flange of the bridge girder.
Span - See Crane Span
Span (Jib Crane) - For a jib crane, span is the
distance from the center of the pivot point to the end of the boom. Note that
"span" is greater than actual working span or hook coverage.
Standby Crane A crane which is not in regular
service, but is used occasionally or intermittently as required.
Stop A device to limit travel of a trolley or
crane bridge. This device is normally attached to a fixed structure and does not
have energy absorbing ability.
Storage Bridge Crane A gantry type crane of long
span used for bulk storage of material; the bridge girders or trusses are
rigidly or non-rigidly supported on one of more legs. It may have one or more
fixed or hinged cantilever ends.
Support Column - A separate column which supports
the runway beam of a top running crane.
Supporting Structure (Jib Crane) - For a free
standing jib crane the supporting structure is the foundation which the crane is
bolted to or implanted in. For a wall bracket or wall cantilever jib crane, the
supporting structure is the wall or column to which the crane is bolted. Mast
type jib cranes have a supporting structure at both the ceiling and the floor.
Suspension system - The system (rigid or flexible)
used to suspend the runway beams of under hung or monorail cranes from the
rafter of the building frames.
Switch - A device for making, breaking, or changing
the connections in an electric or pneumatic circuit (valve).
Thrust and Pull - Forces exerted by a jib crane on
its supporting structure. Thrust is the pushing (or compressive) force exerted
on the structure, while Pull is the tensile force. Thrust and Pull are thus
equal (but opposite in direction) to each other. The maximum thrust and pull
occurs when the crane is loaded at full capacity.
Trolley - The mechanism that carries the hoist
across the bay along the bridge girder(s) navigating the span.
Trolley Hoist - The unit consisting of both the
hoist and the trolley frame.
Trolley Travel - The trolley movement perpendicular
to the crane runway
Truck [Endtruck] The unit consisting of a frame,
wheels, bearings, and axles which supports the bridge, girders or trolleys.
Top Running - The crane bridge travels on top of
rails mounted on a runway beam supported by either the building columns or
columns specifically engineered for the crane.
Under Running - The crane bridge travels on the
bottom flange of the runway beam which is usually supported by the roof
Variable Frequency Drive (VFD ) - A device used in
conjunction with a pendant to vary the frequency of the motors controlling the
motions allowing for smooth acceleration and deceleration.
Wall Crane A crane having a jib with or without
trolley and supported from a side wall or line of columns of a building. It is a
traveling type and operates on a runway attached to the side wall or columns
Welded Link Chain - A hoist chain consisting of a
series of interwoven links formed and welded.
Wheel Base - The distance from center to center of
the outermost wheels.
Wheel Load - The load without impact on any wheel
with the trolley and lifted load (rated capacity) positioned on the bridge to
give maximum loading.
Wire Rope Hoist - A very durable hoist that will
provide long term, reliable usage.
Working Span - The working span (or hook coverage)
of a jib crane is less than the span of the crane. It is a function of the
maximum hook reach and the ability to get the trolley close to the mast. Working
span = (distance between trolley stops) - (hoist trolley length)