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Hoist Terminology

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A

Abnormal operating conditions:

Environmental conditions that are unfavorable, harmful, or detrimental to or for the operation of a crane, such as excessively high or low ambient temperatures, exposure to  adverse weather, corrosive fumes, dust-laden or moisture-laden atmospheres, and hazardous locations. 

Auxiliary hoist:

A supplemental hoisting unit, usually designed to handle lighter loads at a higher sped than the main host.

B

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.

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. 

Brake:

A device, other than a motor, used for retarding or stopping motion by friction or power means.

Brake, holding:

A friction brake for a hoist that is automatically applied and prevents motion when power to the brake is de-energized.

Brake, mechanical load:

An automatic type of friction brake 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 by friction or power.

Braking means, control:

A method of controlling speed by removing energy from the moving body or by imparting energy in the opposite direction.

Braking means, countertorque (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 speed by using the motor as a generator, with the energy being dissipated by resistance.

Braking means, eddy current:

A method of controlling or reducing speed by means of an energy induction load brake.

Braking means, mechanical:

A method of controlling or reducing speed by friction.

Braking means, pneumatic (air):

A method of controlling or reducing speed by means of a compressed gas.

Braking means, regenerative:

A method of controlling speed in which the electrical energy generated by the motor is fed back into the power system.

C

Chain guide:

See Guide, chain.

Chain, hand:

The chain grasped by a person to apply force required for the lifting or lowering motion.

Chain, load:

The load-bearing chain in a hoist.

Chain, roller:

A series of alternately assembled roller links and pin links in which the pins articulate inside the busihings and the rollers are free to turn on the bushings. Pins and bushings are press fit in their respective link plates.

Chain, welded link:

A chain consisting of a series of interwoven links formed and welded.

D

Designated person:

A person selected or assigned by the employer or the employer’s representative as being competent to perform specific duties.

Drum:

The cylindrical member around which the wire rope is wound for lifting or lowering the load. 

Duty cycle:

The working requirements of a crane or hoist as defined by HMI, CMAA or FEM classifications.

E

End user:

The owner and physical location of the user of the overhead lifting equipment in question.

Engineered lift:

This is a lift of more that the rated capacity of a crane or hoist that allows for the rare occurrence when there is no other real alternative. First the manufacturer of unit must be notified and respond in writing that the detailed lift is permissible, then the crane must be inspected to be sure all of the components are operating correctly, the lift is then made, once the area is cleared of all unnecessary personnel. After the lift cycle is completed, the crane must be inspected again to make certain that no damage was done to the crane and its components and is safe to put back into normal operation. Detailed records of this entire event must be maintained by the end user.

Explosion proof:

This is an electrical specification and includes a variety of electrical components 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.

F

Failure rating:

For standard hoists and cranes, the ratio for strength to failure is 5:1.

FEM:

European crane and hoist duty rating system, similar the U.S. HMI and CMAA rating systems.

Fleet angle:

The angle formed by the wire rope and the drum or sheave grooves.

G

Guide, chain:

A means to guide the load chain at the load sprocket.

H

Hand chain wheel: 

See Wheel, hand chain.

Hazardous locations (classified as explosion proof and/or spark resistant):

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.

  • Class 1: Where flammable gases or vapors are, or may be, present in the air in quantities sufficient to produce explosive or ignitable mixtures
  • Class 2:  Which are hazardous because of the presence of combustible dust
  • Class 3:  Hazardous be¬cause of the presence of easily ignitable fibers or filings, but in which such fibers or filings are not likely to be in suspension in the air in quantities sufficient to produce ignitable mixtures

HMI:

Hoist Manufacturers Institute, a division of CMAA.

Hoist:

An under running or top running machinery unit which is used for lifting or lowering a live load. When more than one hoist is mounted on a bridge, the larger capacity unit is typically called out as the Main hoist and the smaller unit is designated as the Auxiliary hoist.

Hook approach:

The minimum horizontal distance, perpendicular to the runway, between the centerline of the hoist hook and the centerline of the runway rail.

Hook latch:

A normally spring loaded mechanical device to close the throat opening of the hoist hook.

I

Ice cube relay:

A plug-in module in some crane and hoist electrical components, such as the push button station or control panels. Most commonly used by some European manufacturers.

J

Jogging (or inching):

To move the hook, trolley, or bridge in a series of short, repetitive, depressions of the function controller button.

K

L

Lift:

The maximum vertical distance (upper and lower) through which a load hook can travel.

Lifting devices:

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). 

Limit switch:

A device designed to cut off the power automatically at or near the limit of travel for the hoist, trolley or bridge motions.

Load:

The total lifted weight on the load block or hook. 

Load block (bottom block):

The assembly of hook, swivel, bearing, sheaves, pins, and frame suspended by the hoisting rope or load chain.

Load chain:

See Chain, load.

Load cycle:

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. 

Load, rated:

The maximum load for which a hoist is designated by the manufacturer or a qualified person.

Load spectrum:

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.

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.

Load test:

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.

Lock out – tag out:

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.

M

Magnetic control:

A means of controlling direction and speed by using magnetic contactors and relays.

Mainline contactor:

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.

Mainline disconnect switch:

A manual knife type switch which breaks the power leading from the switch to the mainline conductors to the crane or hoist.

Manual-magnetic disconnect switch:

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.

N

Normal operating conditions:

Conditions during which a hoist is performing functions within the scope of the original design.  

O

Overload:

Any load greater than the rated capacity of the hoist.

Overload limit device:

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.

Overtravel restraint:

A device used to prevent the slack load chain from inadvertently being lowered out of the load sprocket..

P

Parts (lines):

Number of lines of rope or chain supporting the load block or hook

Pendant station:

Controls suspended from the hoist for operating the unit from the floor.

Pitch diameter (rope):

Distance through the center of a drum or sheave from center to center of a rope passed about the periphery.

Plain reversing control:

A reversing control which has identical characteristics for both directions of motor rotation.

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.

Power transmission parts:

The machinery components including gears, shafts, clutches, couplilngs, bearings, motors and brakes.

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 upper-limit device.

Push button station (pendant):

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.

Q

Qualified person:

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. 

R

Rated load:

See Load, rated.

Reeving (rope):

The reeving of the hoist is the path of the rope between the hoist and the load block.

  • Double reeving is two parts of wire rope leading off of the drum, one from each end of the drum, creating a hook movement referred to as True Vertical Lift. 
  • Single reeving is one part of the line leading off of the drum in which the hook travels horizontally across the drum during the lift cycle resulting in some measure of hook “drift”.

Roller chain:

See Chain, roller.

Rope sheave:

A grooved wheel used with a rope to change direction and point of application of a pulling force. 

S

Service Class:

The working requirements of a crane or hoist as defined by HMI, CMAA or FEM classifications.

Sheave:

A grooved wheel or pulley used with a rope or chain to change direction and point of application of a pulling force.

Sheave, nonrunning:

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.

Sheave, running:

A sheave that rotates as the load block is lifted or lowered.

Side pull:

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.  

Spark resistant:

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.

Sprocket, idler: 

A freely rotating device that changes the direction of the load chain. 

Sprocket, load:

A hoist component that transmits motion to the load chain. This component is sometimes called load wheel, load sheave, pocket wheel or chain wheel.

Stepless control:

A type of control system with infinite speed control between minimum speed and full speed.

Stepped control:

A type of control system with fixed speed points.

Switch:

A device for making, breaking or changing the connection in an electric or pneumatic circuit (valve).

Switch, emergency stop:

A manually actuated switch to disconnect power independently of the regular operating controls.

SWL:

Safe Working Load; another way to callout the rated capacity of a hoist, crane or monorail system.

T

Tag out:

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.

TENC:

Totally enclosed fan cooled, motor type.

TENV:

Totally enclosed non-ventilated, motor type.

Torque, full load (motor):

The torque produced by a motor operating at its rated horsepower and speed.

Trolley:

A wheeled mechanism that carries a hoist and which provides horizontal motion of the hoist along a beam.

Trolley frame:

The basic structure of the trolley on which are mounted the hoisting and traversing mechanisms. 

Trolley hoist:

A hoist and trolley unit consisting of a hoist suspended from or mounted to a trolley, or a hoist with an integral trolley.

True vertical lift:

In true vertical lift, the load hook travels in an exactly vertical path between the lower limit and the upper limit of lift. 

Two blocking:

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.

U

V

Variable frequency drive:

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.

Voltage drop:

The loss of voltage in an electric conductor between supply tap and load tap.

W

Welded link chain:

See Chain, welded link.

Welded, hand chain:

A wheel with formed pockets on its periphery to allow torque to be transmitted when a force is applied to the hand chain.

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.

Wheelbase:

Distance from center-to-center of outermost wheels on a trolley or end truck.

Wire markers:

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.

X

Y

Z

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Office: 253-863-6661
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