Abnormal Operating Conditions

Abnormal operating conditions are environmental conditions, which are potentially harmful or detrimental to the operation of a crane. Examples include: Excessively high or low ambient temperatures, exposure to adverse weather, corrosive fumes, and hazardous locations.

Adjustable or Variable Voltage

A method of bridge crane control that allows the motor supply voltage to be adjusted.


Alu-tracks are crane bridges and/or runways made from maintenance-free, non-corroding, spark-resistant, aluminum enclosed track.

Ambient Temperature

Ambient temperature is a term that refers to the temperature of the atmosphere surrounding (and directly impacting) the hoist and crane. Ambient temperature is influenced by a number of factors, including the weather, the quality of the insulation in a room, and the use of heating and cooling systems.


Ampacity is defined as the maximum amount of electrical current a conductor or device can carry (expressed in amperes).

Anchor Bolts

Anchor bolts are used to attach objects or structures to concrete.


The American National Standards Institute.

Articulating Jib Crane

The word “articulating” refers to something that is connected by joints. Articulating jib cranes offer a material handling solution for applications moving around beams and corners, or reaching under and into machinery. Articulating jibs can be floor, wall, ceiling, or bridge crane mounted to suit a particular application.

Auxiliary Hoist

An auxiliary hoist is an additional hoist that is used to supplement the main hoist on a crane. The auxiliary hoist is designed to handle lighter loads at a higher speed than the main hoist.


A beam is a long piece of squared metal that spans part of a building; it is used as the overhead structure that supports the trolley hoist and load.

Bearing Life

Bearing life is expressed as the number of hours a bearing will operate before the first evidence of metal fatigue develops in the rings. Terms commonly used to refer to the bearing life expectancy are B10 and L10. The basic rating life, L10 is defined as the bearing life associated with 90 percent reliability when operating under conventional conditions. It is also referred to as the minimum expected life.


B.H.N. is an acronym for the term Brinell Hardness Number. The BHN is the measurement of material hardness.

Block, Load

The load block is an assembly of hook or shackle, swivel, bearing, sheaves, pins, and frame that is suspended by the hoisting rope.  In a “short type” block, the hook and the sheaves are mounted on the same member (the swivel). In a “long type” block, the hook and the sheaves are mounted on separate members.

Block, Upper

The upper block is a fixed assembly of sheaves, bearings, pins, and frame that is located on the trolley cross members. The upper block supports the load block and its load using ropes.

Boom (Overhead Cranes)

An overhead crane boom is a horizontal member that is mounted on the trolley. The boom allows a load to be hoisted or lowered at a point that is not directly under the hoist drum or trolley.

Branch Circuit

The branch circuit is part of a distribution system that consists of circuit conductors. It is between the final over current protection and the outlet or load attached.


The bridge is a part of an overhead crane that consists of the girders, trucks, end ties, and drive mechanism. The bridge carries the trolley and travels in a direction parallel to the runway.

Bridge Conductors

The bridge conductors are electrical conductors that are located along the bridge and provide power to the trolley.

Bridge Rail

The bridge rail is where the trolley travels and is supported by the bridge girder.


A bumper is an energy-absorbing device that is mounted on either the end truck or the trolley to reduce the impact when the truck or trolley comes into contact with its end stop or another truck or trolley.


The camber is a vertical curve design applied to girders to compensate for deflection due to the hook load and the weight of the crane.


A cantilever is a long projecting beam or girder that is only fixed at one end. The cantilever is the structural member that supports the trolley on a wall crane.


Capacity is the maximum rated load that a crane is designed to handle safely.

(Trolley) Carrier

The carrier, or trolley, is a unit that travels along a monorail track, jib boom, or bridge girder to transport a load.

Ceiling Mounted

Ceiling mounted is a type of system mounting that allows an overhead crane to be hung from existing roof beams or trusses. Ceiling mounted cranes require no system support columns, no building column attachments, and no production floor space.


Clamps are a type of suspension fitting used to support tracks from an overhead structure. The clamps allow the tracks to be fastened to the overhead structure using pressure rather than welding or bolting.


Clearance is the minimum distance from any part of the crane to the nearest obstruction.


CMAA is an acronym that stands for the Crane Manufacturers Association of America.

Conductors, Bridge

Bridge conductors are electrical conductors located along the bridge girders. Conductors are used to provide power and Bridge Crane Control circuits to the trolley.

Conductors, Runway (Main)

Runway conductors are electrical conductors located along a crane runway. Runway conductors are used to transmit bridge crane control signals and to send power to the crane.


A contactor is an electromechanical device used to open and close an electrical power circuit.

Controller (Bridge Crane)

The controller is a device used to control the level of power delivered to the motor or other parts.


A crane is a type of machine, generally equipped with a hoist, wire ropes or chains, and sheaves, that can be used both to lift and lower materials and to move them horizontally. It is mainly used for lifting heavy things and transporting them to other places. It uses one or more simple machines to create mechanical advantage and thus move loads beyond the normal capability of a human. Cranes are commonly employed in the transport industry for the loading and unloading of freight, in the construction industry for the movement of materials and in the manufacturing industry for the assembling of heavy equipment.

Creep Speed

Creep speed is considered a slow, fixed rate of movement that applies to the hoist, trolley, or bridge; creep speed is usually anywhere from one to ten percent of the normal full load speed.

Cushioned Start

A cushioned start is an electrical (or mechanical) method used to reduce the trolley’s rate of acceleration.

Double Girder Crane

A double girder crane is a crane with two bridge girders mounted between the end trucks. Double girder cranes provide additional clearance, because the hoist is placed between the cross girders rather than under them.

Drive Girder

The drive girder is where the bridge drive’s machinery is mounted.


The drum is a cylindrical device that holds the rope used for lifting or lowering a load.

Dynamic Lowering (braking)

Dynamic lowering is a speed-controlling method where the motor is used as a generator and energy is dissipated because of resistance. Dynamic braking lowers the wear of friction-based braking components and reduces energy consumption.

Enclosed Conductor

Enclosed conductors are totally surrounded to prevent accidental contact and to keep out contaminants.

Enclosed Track Workstation

This type of workstation crane uses an enclosed track design to help keep out contaminants and dust.


An enclosure is used to house (and contain) electrical components.

End Approach

The end approach is the minimum horizontal distance between the outermost extremities of the crane and the centerline of the hook.

End Stop

An end stop is a device used to limit trolley travel or bridge travel. The end stop is usually attached to a fixed structure, and, unlike a buffer, it does not have energy absorbing abilities.

End Truck

The end truck is an assembly of parts including the frame and wheels that support the girders and allow movement along the runway.


A fail-safe is a provision designed to stop or safely control any motion whenever a malfunction occurs.

Festooned Cable System

A festooned cable system is a clean, economical and efficient method of managing power and cables for mobile equipment. Festoon systems are generally used on overhead cranes for the transmission of power for cross bridge trolley travel, but they can also be used for crane runway travel.

Field Wiring

Field wiring refers to the wiring that is required after the crane has been erected.

Floor Operated Crane

A floor operated crane is a crane that is suspended or overhanging and controlled by an operator on the floor or on an independent platform.

Freestanding Jib Crane

A freestanding jib crane is a jib crane that can be installed almost anywhere, including outdoors. Freestanding jib cranes are typically foundation mounted, and they offer higher capacities, longer spans, and greater rotation than wall-mounted jib cranes.

Freestanding Workstation Bridge Crane

A freestanding workstation bridge crane is a bridge crane that is not ceiling mounted, but rather, freestanding. The runways are usually installed above the floor without the use of footers, which means they can be readily relocated, easily expanded or modified, and they don’t rely on the support of the roof for use and installation.

Gantry Crane

A gantry crane is a crane with a bridge beam supported on two or more legs that run parallel on fixed rails or a runway.

Gantry Leg

The gantry leg is a structural member, which supports the girder or end tie from the sill.


Gauge is the center-to-center distance between the load carrying flanges of the two crane girders on a double girder crane.


Girders are the principal horizontal beams of the crane, and they are supported by the end trucks and sit perpendicular to the runway. The carrier (or trolley) travels along the bridge girder to transfer loads.

Hanger Rod

A hanger rod is a steel rod that is used to suspend the track from the supporting structure.


The hoist is a machinery unit that is used to lift and lower a load.

Holding Brake

A holding brake is a friction brake that is automatically applied to the hoist and prevents motion when power is off.

Hook Approach

The hook approach is the minimum horizontal distance between the center of the runway rail and the hook.

Impact Allowance (Impact Factor)

Impact allowance, also known as impact factor, is additional hook load, which is the result of the dynamic effect of the live load.

Interlock Mechanism

The interlock mechanism is a mechanical device used to lock together the adjacent ends of two cranes (or a crane to a crossover) to permit the transfer of carriers from one crane or track to the other.

Jib Boom

A jib boom is a horizontal cantilever track that supports the trolley or carrier.

Jib Crane

A jib crane is a type of crane where a horizontal member (jib or boom), supporting a moveable hoist, is fixed to a wall or to a floor-mounted pillar. Jib cranes are used in industrial premises and on military vehicles. The jib may swing through an arc, to give additional lateral movement, or be fixed. Similar cranes, often known simply as hoists, were fitted on the top floor of warehouse buildings to enable goods to be lifted to all floors.

Jog (Inch)

The word jog refers to the movement of the hook, trolley, or bridge in a series of short, discontinuous increments using a bridge crane controller.


This is an acronym that stands for kips per square inch. It is a measurement of stress intensity.


A kip is a unit of force, equivalent to 1000 pounds. (CMAA Spec. 70)

Knee Brace

The knee brace is the diagonal structural member that joins the building column and roof truss.

Lateral Hook Travel

The lateral movement of the load hook between its position at the upper limit of travel and its position at the lower limit of travel is referred to as lateral hook travel.


Lift refers to the maximum vertical distance that the hook, magnet, or bucket can move.

Lifting Devices

Lifting devices include buckets, magnets, grab, and supplemental devices. The weight of these supplemental devices is considered to be part of the rated load.


Load refers to the total superimposed weight on the load block or hook.

Load Block

The load block is comprised of the hook or shackle, swivel, bearing, sheaves, pins, and frame, all of which are suspended by the hoisting rope or load chain.

Longitudinal Stiffeners

Longitudinal stiffeners are the horizontal members attached to the web of the bridge girder; they are used to prevent web buckling.

Main Hoist

The main hoist is the largest hoist on a crane and it also determines the maximum weight a crane can lift. The main hoist is provided for lifting and lowering a rated load.

Main Line Contractor

The main line contractor is a magnetic contractor used in the incoming power circuit from the main line collectors.

Main Line Disconnect Switch

A manual switch that breaks the power lines leading from the main line collectors.

Mast Style Jib Crane

Mast style jib cranes are a lower cost alternative to freestanding jib cranes. They do not require a foundation or large base plate. They do require mounting at the top and the bottom, and they provide full 360-degree rotation. Mast style jib cranes are available in both a full and drop cantilever.

Mast Style Jib Crane-Drop Cantilever

The mast style jib crane with drop cantilever is identical to the full cantilever with the addition of side plate connections to permanently “drop mount” the boom at any specified height on the mast. Drop cantilever booms allow for clearance from overhead obstructions that are located below the top of the mast.

Mast Style Jib Crane-Full Cantilever

The mast style jib crane with full cantilever provides maximum clearance by mounting the cantilevered boom at the top of the mast.

Master Switch

The master switch is a manually operated device that is used to govern the operation of contactors and auxiliary devices for an electric bridge crane control.

Mechanical Load Brake

Mechanical load brake is an automatic type of friction brake used for bridge crane controlling loads in a lowering direction. This unidirectional device requires torque from the motor to lower a load but does not impose additional load on the motor when lifting.


A monorail is the overhead track where the trolley (carrier) travels. It is used to transport loads.

Multiple Girder Crane

A multiple girder crane is a crane that has two or more girders, which both support the live load.

Overhead Bridge Crane

An overhead bridge crane is a bridge crane that is ceiling mounted to preserve floor space and make the most of an existing workspace and production area. Overhead cranes hang from existing roof beams or trusses and do not require system support columns, attachments to building columns, or production floor space. An overhead bridge crane also allows users to easily expand runway lengths, add more bridges, and add links to monorail crane systems.


The word “overload” refers to any load greater than the rated load.

Overload Limit Device

An overload limit device is a mechanical or electrical apparatus that prevents the crane from lifting loads greater than the safe working load.

Protective Panel

A protective panel is an assembly containing overload and under voltage protection for all crane motions.

Push Button Station

A push button station is an electrical bridge crane control device, which consists of contacts that are operated using a push button to control the powered motions of the crane, hoist, and auxiliary equipment.

Rail Sweep

A rail sweep is a device attached to the crane and located in front of the crane’s leading wheels to push aside loose obstructions.

Rail, Bridge

The bridge rail is the track where the trolley travels, which is supported by the bridge girder(s).

Rail, Runway

The runway rail is the track where the trolley travels.

Rated Load (Capacity)

The maximum rated load that a crane is designed to handle safely.


Reach is equal to lift plus headroom.

Regulated Speed

Regulated speed is a function that maintains constant motor speed for any load, using a given speed setting on the bridge crane controller.

Remote Operated Crane

A remote operated crane is controlled by an operator (not in the pulpit or the cab) using any method other than pendant or rope control.

Resistor Rating

The resistor rating was established by NEMA, and it classifies resistors according to percent of full load current on first point and duty cycle.

Retrofit Jib Drive Unit

A retrofit jib drive unit is a motorized component, which can be added to a manual jib crane after installation to power the machine.

Rotating Axle

A rotating axle is an axle that rotates with the wheel.


The runway consists of the rails, beams, brackets and framework on which the crane operates.

Runway Conductors

Runway conductors are the main conductors mounted on or parallel to the runway; they supply current to the crane.

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