A method of control by which the motor drives through an electrical induction load brake.
A method of controlling one or more of the crane motor speeds without the use of friction braking.
A housing to contain electrical components, usually specified by a NEMA classification number.
A structural member, other than the end truck, which connects the ends of the bridge girders to maintain the squareness of the crane bridge.
European crane and hoist duty rating system, similar the U.S. HMI and CMAA rating systems.
Looped wires, now commonly flat cable, that carry power and control across a bridge or along a runway or monorail.
The wiring required after erection of the crane.
Motor driven cranes which are controlled by an operator on the floor by means of pushbutton station suspended from the overhead equipment.
A crane similar to an overhead crane except that the bridge for carrying the trolley or trolleys is rigidly supported on two or more legs running on fixed floor mounted rails or other runway. These can typically come in two styles; a semi-gantry (or single leg) which has one leg fixed to a floor running truck and one truck fixed to the other end of the bridge that runs on a more conventional runway beam and rail that is supported by the building columns at bridge height. The other type is a full gantry (or double leg) which has legs at both ends of the bridge with trucks running on two floor mounted rails.
See Wheel, hand chain.
Where fire or explosion hazards may exist and are classified depending on the properties of the flammable vapors, liquids or gases or combustible dusts or fibers which may be present and the likelihood that a flammable or combustible concentration or quantity is present.
The seat fastened to an upright column on which the runway beams for a top running crane sit. These connections are best made when bolted.
Headroom is the distance measured from the saddle of the load hook, when in it’s highest lift position; typically to the following locations:
Hoist Manufacturers Institute, a division of CMAA.
A friction brake for any of the crane’s motions that is automatically applied and prevents motion when power is off.
The minimum horizontal distance, perpendicular to the runway, between the centerline of the hoist hook and the centerline of the runway rail.
A normally spring loaded mechanical device to close the throat opening of the hoist hook.
The 4-wire power connection leads that are provided by the purchaser’s electrical contractor and left at the conductor connection point to be tied into mainline power delivery method by the crane system installer.
International Electric Code.
Horizontal forces perpendicular to the axis of the member being considered. When used in reference to a crane runway being braced back to your building, you can estimate the lateral load that your structure will realize to be approximately 220 lbs. per ton of lifted load.
The maximum vertical distance (upper and lower) through which a load hook can travel.
A single lifting and lowering motion (with or without load).
Devices which are not considered to be a fixed part of the hoist, such as hook suspended 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 when specifying the desired capacity of a crane, hoist, runway or monorail system (including the supporting structure).
A device designed to cut off the power automatically at or near the limit of travel for the hoist, trolley or bridge motions.
A contactor to disconnect power from the supply lines.
A load which moves relative to the structure under consideration.
The total lifted weight on the load block or hook.
The assembly of hook, swivel, bearing, sheaves, pins, and frame suspended by the hoisting rope or load chain.
See Chain, load.
Lowering of the hook to pick up a load, one lift with the load, one lowering of the load, plus one lift without the load, returning the hook to the original position.
The maximum load for which a hoist is designated by the manufacturer or a qualified person.
The average daily operating time of a crane or hoist, calculated in order to determine the proper service class of the equipment the application requires.
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.
This type of test is performed in the field to determine the integrity of the system as a whole. It is recommended that the test be @ 125% of the rated capacity and include travel to all limitations of the system as well as a timed hoist brake test to detect brake slippage outside the range of acceptance. Do not accept the factory hoist load test certificate alone in lieu of the completed field test as it only verifies the hoist mechanism itself and does not confirm that the entire system is sound and safe to operate.
Method by which a crane system mainline power disconnect is turned off and the knife switch handle is locked in the “off” position by one or more pad locks. These locks have a tag with the name of the individual locking out the crane. It is not permitted to remove someone else’s lock as this could put this individual in great danger of serious injury or death due to electrocution.
Horizontal members attached to the web of the bridge girder to prevent web buckling. These can also be part of a runway, monorail or other crane structural support system.
A means of controlling direction and speed by using magnetic contactors and relays.
Rigid conductor bars, festoon system or cable reel that delivers the mainline power along the runway or monorail.
A magnetic contactor located in the main control panel, used in the incoming power circuit from the main line collectors, to pull in or drop out the power supply, to the crane or hoist.
A manual knife type switch which breaks the power leading from the switch to the mainline conductors to the crane or hoist.
A power disconnecting means consisting of a magnetic contactor that can be operated by remote pushbutton and can be manually operated by a handle on the switch.
A manually operated device which serves to govern the operation of contactors and auxiliary devices of an electric control.
Identification of non-interchangeable parts for reassembly after shipment. These are typically used on the crane, runway and structural support components.
A load used in durability calculations accounting for both maximum and minimum loads.
An automatic type of friction brake used for 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 load.
Service classification covered by AISE Standard No. 6, Specification for Electric Overhead Traveling Cranes for Steel Mill Service.
The tolerances to which the steel mills produce their products. These are typically much less exacting than what is required by the hoist and crane industry for bridge girder, runway and monorail sections. This causes the need for the crane fabricators to quite often re-work the straightness and flange relationships on many of the sections before they can be built into an overhead lifting system that meets CMAA tolerances.
Monorail Manufactures Association, a division of CMAA.
The forces applied to a column and base plate that want to pull it loose from the floor. These are most prevalent with full cantilevered columns.
A single line overhead track, from which a hoist & trolley unit is suspended, used to transport loads. These can be simple straight line tracks or more complicated with switches, curves and interlocks that connect to cross over sections that allow the hoist & trolley to travel onto under running bridge cranes.
National Electric Code.
Conditions during which a crane system is performing functions within the scope of the original design.
A walking speed assumed to be 125-150 feet per minute.
The operator’s compartment from which movements of the crane are controlled. To be specified by the manufacturer as open, having only sides or a railing around the operator, or enclosed, complete with roof, windows, etc.
Any load greater than the rated capacity of an overhead lifting system.
A device that is part of the hoisting unit that senses when an attempt is made to exceed the capacity (safe working load) of the hoist and interrupts the lift circuit.
A device operative on excessive current to cause and maintain the interruption or reduction of current flow to the equipment governed.
A device used to prevent the slack load chain from inadvertently being lowered out of the load sprocket.
Number of lines of rope or chain supporting the load block or hook.
A generic term that refers to crane and monorail equipment built in accordance with the MMA specification utilizing a composite track section incorporating a proprietary bottom flange shape.
Professional Engineer. An individual qualified to design part or all of an overhead lifting system and this design should always bear the engineer’s registration stamp.
Means suspended from the crane operating the controllers from the floor or other level beneath the crane.
Controls suspended from the hoist for operating the unit from the floor.
The power source on a new construction project that allows for the crane system installation to be energized and tested.
Distance through the center of a drum or sheave from center to center of a rope passed about the periphery.
A reversing control which has identical characteristics for both directions of motor rotation.
System that allows for connecting most crane electrical components together with plugs and receptacles, eliminating the need for hard wiring.
A control function which accomplishes braking by reversing the motor line voltage polarity or phase sequence.
Point of Lowest Obstruction: Any building structure, i.e. lights, HVAC ductwork, electrical conduit, etc., above the crane operating area.
The machinery components including gears, shafts, clutches, couplilngs, bearings, motors and brakes.
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 upper-limit device.
Either an “S” or wide flange beam.
An assembly containing overload and undervoltage protection for all crane motions.
An electrical control device, consisting of push button operated contacts, used by the operator for the control of the powered motions of the crane, hoist, and other auxiliary equipment.
A person who, by possession of a recognized degree or certificate of professional standing or by extensive knowledge, training, and experience, has successfully demonstrated the ability to solve or resolve problems relating to the subject matter and work.
A crane operated from a radio transmitter located at a point not mechanically attached to the crane being controlled. The bridge main control panel has a receiver that transmits the desired commands to the difference crane functions.
A device attached to the bridge end trucks (and trolley end trucks for double girder top running trolleys) and is located in front of the truck’s leading wheels to push aside loose obstructions from the running surface.
See Load, rated.
The reeving of the hoist is the path of the rope between the hoist and the load block.
A method of controlling speed in which the electrical energy generated by the motor is fed back into the power system.
A function which tends to maintain constant motor speed for any load for a given speed setting of the controller.
Request for quote. This should include a detailed specification of the equipment, location for installation, time frame for delivery and any special conditions or terms as anticipated by the requester.
See Chain, roller.
A grooved wheel used with a rope to change direction and point of application of a pulling force.
An axle which rotates with the wheel and is connected directly to the drive motor or gear box by a splined or keyed shaft.
The rails, beams, brackets and framework on which the crane operates. These can be building column seated on haunches, semi-free standing (braced back to the building) or totally free standing cantilevered columns and may or may not require foundations.
The rail supported by the runway beams on which the bridge travels. These can be ASCE type rails which can be attached to the runway beam top flanges by J-bolts or clips or square bar sections that are welded to the beam top flanges.
A standard structural beam shape as defined by the American Institute of Steel Construction.
A mechanical device fixed securely to the end truck or trolley yoke which will limit the fall of the crane or carrier in case of wheel or axle failure.
The working requirements of a crane or hoist as defined by HMI, CMAA or FEM classifications.
Where two sections are connected end-to-end (as opposed to stacked) with plates that are bolted and tightened to specific torque specifications to create adequate friction to hold the load.
A grooved wheel or pulley used with a rope or chain to change direction and point of application of a pulling force.
A 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.
A sheave that rotates as the load block is lifted or lowered.
The action of the hoist wire rope pulling horizontally against the grooves of the drum when the hook is not operated straight up and down and can result in an unsafe condition and/or damage to the equipment.
Method by which two or more movements of a crane system can be operated together or separately. Either actuated by a selector switch, or separate control buttons for each function, on the controller.
Lateral forces on the bridge truck wheels caused by the bridge girders not running in a perpendicular direction to the runways. Some normal skewing occurs in all bridges.
The horizontal distance center-to-center of runway rails.
This is a mechanical specification and includes a variety of alterations to the components of the unit that must be supplied as per the demands of the Group, Class and Division of the hazardous area in which they are expected to operate.
A mechanical device used to join the adjacent ends of runway, monorail and/or ASCE runway rail sections.
A freely rotating device that changes the direction of the load chain.
A hoist component that transmits motion to the load chain. This component is sometimes called load wheel, load sheave, pocket wheel or chain wheel.
A method of switching electrical circuits without the use of contacts.
A type of control system with infinite speed control between minimum speed and full speed.
A type of control system with fixed speed points.
The average tensile force per unit of cross sectional area required to rupture the material as determined by test.
Load or force per unit area tending to deform the material usually expressed in pound per square inch.
The structure used for the support of a crane and runway or monorail system.
Fittings used to attach an under running runway or monorail track to the supporting structure.
Maximum lateral deviation from straightness of a structural member, measured at right angles to the X-Y axis.
A device for making, breaking or changing the connection in an electric or pneumatic circuit (valve).
A manually actuated switch to disconnect power independently of the regular operating controls.
Safe Working Load; another way to callout the rated capacity of a hoist, crane or monorail system.
Procedure by which a qualified service technician shuts down the availability of an overhead lifting system due to an unsafe or damaged condition that needs to be corrected or repaired. DO NOT use this equipment as long as it remains tagged out.
An electrical conductor system employing flexible steel wire cables for suspension of the conductor cables either by “S” hooks or small rolling trolleys.
Totally enclosed fan cooled, motor type.
Measures the force required to pull something, such as a wire rope or a structural beam, to the point where it breaks.
Totally enclosed non-ventilated, motor type.
An electric overhead traveling crane having the end trucks supported on rails attached to the top of the crane runway beams.
The torque produced by a motor operating at its rated horsepower and speed.
Double box girder construction in which the trolley rail is located over the inside webs of both girders.
Forces which can cause twisting of a structural member.
The structural member of an under running crane or monorail that supports the carrier or crane wheels.
A motor driven unit supported from wheels and propelled by friction drive wheel bearing on the underside of the track.
Other contractors on a job site that your installer needs to work with, or around, in order to get the installation completed.
A switch, usually located on the face of the main control panel, that allows for changing the method of control from a push button station to a radio, and back.
A wheeled mechanism that carries a hoist and which provides horizontal motion of the hoist along a beam.
The basic structure of the trolley on which are mounted the hoisting and traversing mechanisms.
A hoist and trolley unit consisting of a hoist suspended from or mounted to a trolley, or a hoist with an integral trolley.
In true vertical lift, the load hook travels in an exactly vertical path between the lower limit and the upper limit of lift.
Condition under which the load block or load suspended from the hook becomes jammed against the crane structure preventing further winding up of the hoist drum. This is a very dangerous condition and can result in the hoist motor pulling the rope until it breaks, dropping the load.
An electric overhead traveling crane where the end trucks are supported from the bottom flanges of tracks attached to a structure or supported on bottom flanges of beams. These tracks or beams make up the crane runway.
A device operative on the reduction or failure of voltage to cause and maintain the interruption of power in the main circuit.
A method of control by which the motor supply voltage and frequency can be adjusted thereby allowing for controlled acceleration and deceleration of the driven hoist, trolley or bridge.
The loss of voltage in an electric conductor between supply tap and load tap.
A wide flange beam shape as defined by the American Institute of Steel Construction.
The vertical plate connecting the upper and lower flanges, or cover plates, of a fabricated plate box girder.
See Chain, welded link.
A wheel with formed pockets on its periphery to allow torque to be transmitted when a force is applied to the hand chain.
A written, and repeatable, progression of steps that will yield the best result for a certain type of welded connection.
The load, without impact, on any wheel with the trolley and lifted load (rated capacity) positioned on the bridge to give maximum loading.
Distance from center-to-center of outermost wheels on a trolley or end truck.
Small labels that wrap around the power and control wires in a control panel or junction box that allow the technician to see how things are supposed to be connected and make it easier for them to trouble shoot when there is a problem. Similar markers will also be stuck to the connecting locations on the terminal strips in the panel or j-box.