CRANE Terminology
TROLLEY FRAME
ADJUSTABLE FREQUENCY DRIVE – A motor controller
designed to convert fixed frequency AC power to TROLLEY DRUM
HOIST MOTOR
available frequency power for AC motor speed TROLLEY DRIVE
control. The system is used in conjunction with a
squirrel cage motor to control speed over a
relatively wide, constant torque range, by
maintaining a constant voltage / frequency ratio.
This type of control “leashes” the in-rush current to
deliver startup power to the motor as efficiently
as possible providing a soft-start feature thereby
minimizing load swing.
HOIST GEARBOX
ANTI-COLLISION – An Electrical means of keeping
TROLLEY WHEELS
two (2) or more crane’s from contacting each other.
ANTI-SKEWING – Capability of the crane design to
maintain squareness in relation to the runway structure.
LOWER
AUXILIARY HOIST – A supplemental hoisting unit, usually BLOCK
designed to handle lighter loads at a higher speed than
the main host.
CLEARANCE – Minimum distance from the extremity of a
BOGIE – A type of short end truck, used to allow greater crane to the nearest obstruction.
distribution of crane wheel loads, by placing multiple
wheels at each corner of the crane. C.M.A.A. – Crane Manufacturers Association of America,
Inc. (formerly EOCI—Electric Overhead Crane Institute).
BOX SECTION – The rectangular cross section of girders,
trucks or other members, comprised of two (2) rolled steel COLLECTORS – Contacting devices for collecting current
side plates, a top plate, and a bottom plate. from the runway or bridge conductors. The main line collec-
tors are mounted on the bridge to transmit current from the
BRIDGE – That part of an overhead crane consisting of runway conductors, and the trolley collectors are mounted
girders, trucks, end ties, walkway and drive mechanism on the trolley to transmit current from the bridge conduc-
which carries the trolley and travels in a direction parallel tors.
to the runway.
COVER PLATE – The top or bottom plate of a box girder.
BRIDGE GIRDER – The main horizontal structural member(s)
of the crane bridge supported by the end trucks. CRITICAL LOAD – Any lifted load whose uncontrolled
movement or release could adversely affect any
CAMBER – The slight upward vertical curve given to girders safety-related system when such a system is required for
to compensate partially for deflection due to hook load unit safety. A crane used for lifting a critical load shall be
and weight of the Crane. designed with single failure proof features so that any
credible failure of a single component will not result in the
CAPACITY – The maximum rated load for which a crane is loss of capability to stop or hold the load.
designed to handle. Measured in tons.
DOUBLE GIRDER CRANE – A crane which runs on two (2)
CASK HANDLING CRANE – A crane specifically designed bridge girders mounted between and supported by end
to handle a cask loaded with spent nuclear fuel. A crane trucks at each runway.
of this type is typically provided with single failure proof
features.
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DRIVE GIRDER – The girder on which the bridge drive without load.
machinery is mounted.
OVERHEAD CRANE – A crane with a moveable bridge
END APPROACH – The minimum horizontal distance, carrying a moveable or fixed hoisting mechanism and
parallel to the runway, between the outermost extremities traveling on an overhead fixed runway structure.
of the crane and the centerline of the hook.
RATED LOAD – The maximum load which the crane is
END TIE – A structural member other than the end truck designed to handle safely
which connects the ends of the girders to maintain the
squareness of the bridge. REEVING – Terminology used to describe the path of the
hoist wire rope as it pays off the hoist drum and wraps
END TRUCK – The unit consisting of truck frame, wheels, around the various upper and lower sheaves.
bearings, axles, etc., which supports the bridge girders.
REGENERATIVE BRAKING – A method of controlling speed
EXPLOSION PROOF CRANE – A crane designed using in which electrical energy generated by the motor is
specially constructed electrical components to prevent feedback into the power system.
the ignition of hazardous materials in the surrounding
atmosphere, by containing any explosions that may RUNWAY – The rails, beams, brackets and framework on
occur within the components. which the crane operates.
FESTOONING – A method for providing power to a hoist SHEAVE – A grooved wheel or pulley used with a rope or
traveling along a beam. chain to change direction and point of application of a
pulling force.
FLUX VECTOR DRIVE – A special type of adjustable frequency
motor control, utilizing an incremental encoder to SINGLE GIRDER CRANE – A crane which runs on a single
constantly monitor the speed and direction of the motor bridge girder.
shaft. This “closed-loop” system allows the control to know
what the motor is doing at all times. Flux vector control SINGLE FAILURE PROOF – Those features that are included in
provides a wide range of speed and reliability in hoisting the crane design such that any credible failure of a single
applications where no mechanical load brake is utilized. component will not result in the loss of capability to stop
and hold the critical load within facility acceptable
GAGE–- Horizontal distance between the centerlines of the excursion limits.
rails that support the trolley on a double girder bridge.
SPAN – The horizontal distance center-to-center of runway
GANTRY CRANE – A crane similar to an overhead crane rails.
except that the bridge for carrying the trolley or trolleys is
rigidly supported on two or more legs running on fixed rails TOP RUNNING CRANE – An overhead traveling crane
or other runway. having the end trucks supported on rails attached to the
top of the runway support beams.
GEAR REDUCER – Device to convert high speed motor shaft
rotation to usable output shaft speed for hoist, trolley or TROLLEY – The unit carrying the hoisting mechanism which
bridge motion. travels on the bridge rails.
GRAPPLE – A “job specific” load handling device, designed TROLLEY FRAME – The basic structure of the trolley on which
to pick up bulk material, containers, barrels or drums. are mounted the hoisting and traversing mechanisms.
Actuation can be mechanical, electrical or hydraulic.
TWO BLOCKING – Condition under which the load block or
HOIST – A mechanism used for lifting and lowering a load. load suspended from the hook becomes jammed against
the crane structure preventing further winding up of the
HOLDING BRAKE – A brake that automatically prevents hoist drum.
motion when power is off.
UNDER RUNNING CRANE – A crane that has a movable
HOOK APPROACH – The minimum horizontal distance bridge running on the lower flanges of a fixed overhead
between the center of the runway rail and the hook. runway structure which has a movable or fixed hoisting
system.
JIB CRANE – A crane design whereby the bridge girder
(commonly called the boom) is fixed at one end, allowing WEB PLATE – The vertical plate connecting the upper and
the opposite end to cantilever. The fixed end generally is lower flanges or cover plates of a girder.
hinged to allow rotation.
WHEEL LOAD – The load without vertical inertia force on any
LIFT – Maximum safe vertical distance through which the wheel with the trolley and lifted load (rated capacity)
hook, magnet, or bucket can move. positioned on the bridge to give maximum loading.
LOAD BLOCK – The assembly of hook, swivel, bearing, WHEELBASE – Distance from center-to-center of wheels,
sheaves, pins and frame suspended by the hoisting ropes. as measured in the direction running parallel with the
support rail.
LOAD CYCLE – One (1) lift cycle with load plus one lift cycle
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