Abnormal Operating Conditions

Abnormal operating conditions are environmental conditions that are potentially harmful or detrimental to crane operation. Examples include excessively high or low ambient temperatures, exposure to adverse weather, corrosive fumes, and hazardous locations.

Adjustable or Variable Voltage

Adjustable or variable voltage is 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, paint-free, 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 many factors, including weather, 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. Ampacity is measured in amperes.

Anchor Bolts

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


An acronym that stands for the American National Standards Institute, ANSI was founded in 1918 and oversees the implementation of thousands of directives and design specifications for the U.S. marketplace.

Articulating Jib Crane

The word “articulating” refers to something that is connected by joints. Articulating jib cranes are 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 structural metal that spans part of a building, usually a wide-flange beam or standard I-beam; it is used as the overhead structure that supports the system.

Bearing Life

Bearing life is expressed as the number of hours a bearing will operate before evidence of metal fatigue develops in the rings. Terms commonly used to refer to the bearing life expectancy are B10 and L10. Although both terms have the same definition, L10 is the preferred term. 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 wire rope.

Boom (Overhead Cranes)

An overhead crane boom is a horizontal member that the trolley mounts to. The boom allows a load to be hoisted or lowered anywhere within the clear span.

Branch Circuit

The branch circuit is part of a distribution system that consists of circuit conductors. The branch circuit is located 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, end trucks, end ties, and if motorized, drive mechanism. The bridge travels parallel to the runways and allows the trolley to travel the full length of the bridge perpendicular to the runways.

Bridge Buffer

Bridge buffers roll in the runway tracks between two bridges to prevent the bridges from overloading the runway’s capacity.

Bridge Conductors

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.

Bridge Runway Height (BRH)

Bridge runway height is a term commonly used with ceiling-mounted systems. The bridge runway height is the distance from the top of the runway to the trolley clevis.


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


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 crane.


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

Carrier (Trolley)

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 system mounting method that allows an overhead crane to be hung from existing building 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.

Clear Span

Clear span is the actual working span of a crane’s beam or boom.


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.


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. They are mainly used to lift, lower, and move heavy objects to other places. They use one or more simple machines to create a mechanical advantage, allowing the crane to move loads beyond the normal capability of a human. Cranes are commonly employed in the transportation 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 maximum capacity 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 wire 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, which dissipates energy due to 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.

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.

Flange (Flange Thickness and Flange Width)

Flange is the flat outer face of a rolled-steel joist, especially of an I-beam or W-beam. Flange thickness and flange width are common terms associated with ceiling-mounted systems. Flange thickness and flange width are the thickness and width of the flange of the ceiling-support structure to which the crane will be mounted.

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 foundation mounted to concrete. By using headers and columns, most freestanding workstation bridge cranes do not require special 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.


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

Gantry Crane

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

Gantry Leg

The gantry leg is a structural member of a gantry crane that supports the beam.


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 ceiling-support 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.

HUB (Underboom Height)

HUB is an acronym that stands for Height Under Boom or Height Under Beam depending on the crane type. HUB is also referred to as underboom height. HUB is the distance from the floor or lifting surface to the bottom of the crane beam or boom.

Hybrid End Truck

Spanco hybrid end trucks are used when the bridge and runway track sizes are different. Larger or smaller wheels than standard are placed on the bridge end trucks to accommodate the different-sized runways.

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.

Intermediate Bumper

Intermediate bumpers are through-bolted end stops installed at runway support centers to prevent more than one bridge from operating within a set of support centers. Intermediate bumpers should never be used as end stops.

Jib Boom

A jib boom is a horizontal cantilever beam 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 wall mounted or foundation mounted. Jib cranes are used in industrial premises. The jib may pivot 180 or 360 degrees or be fixed.

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.


An acronym that stands for kips per square inch, K.S.I. is a measurement of stress intensity.


A kip is a unit of force equivalent to 1,000 pounds.

Knee Brace

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


Lift refers to the maximum vertical distance that the hook, magnet, or attachment point 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 capacity.


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 wire 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 that determines the maximum weight a crane can lift. The main hoist is provided for lifting and lowering a rated load.

Main Line Contactor

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

Main Line Disconnect Switch

A main line disconnect switch is 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 special 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 design.

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

A 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 that 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 building 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 transitions to monorail crane systems.


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

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 crane control device consisting 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.

Rated Load (Capacity)

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

Regulated Speed

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

Retrofit Jib Drive Unit

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

Rotating Axle

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


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

Runway Conductors (Main)

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

Trolley-Clevis Height

Trolley-clevis height is the distance from the ground or surface to the clevis on the free-rolling trolley.

Tread Width

Tread width is a term commonly used with gantry cranes. Tread width is the distance from the center of a caster mounting plate to the center of the other caster mounting plate on the same leg.

Vertical Hook Travel

The vertical 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 vertical hook travel.