NCCCO Overhead Crane key terms

The maximum load a crane or hoist is designed to lift under a specific set of conditions, as published by the manufacturer in the load chart.

A manufacturer-supplied table or graph showing the maximum allowable load for an overhead crane or hoist under stated conditions, such as trolley position or hoist configuration.

The horizontal structural beam that spans the runway and carries the trolley and hoist. It travels along the runway rails to position loads across the bay.

The elevated rails or tracks, usually mounted on building columns, along which the crane bridge travels. Runway alignment and condition affect tracking and safe load handling.

The frame and wheel assembly that rides along the bridge and supports the hoist, allowing the load to be moved horizontally across the bridge span.

The lifting mechanism, consisting of motor, drum or chain, and reeving, that raises and lowers the load. Hoists may be electric or air powered and are rated separately from the bridge.

The assembly of sheaves and hook suspended below the hoist by wire rope. It multiplies lifting force through reeving and must never contact the hoist drum or upper block.

A condition in which the load block is pulled up until it contacts the hoist's upper block or drum, which can snap wire rope, damage sheaves, and drop the load.

A sensing device that stops hoisting or warns the operator before the load block contacts the upper block, preventing two-blocking damage.

A device that automatically stops the hoist when the load block reaches a set upper travel point, preventing overtravel and two-blocking.

A sensor that detects when the load exceeds the hoist's rated capacity and prevents or warns against further lifting, protecting the crane structure and hoist.

A spring-loaded gate on the hook that closes the throat opening so slings, rings, and shackles cannot slip off during lifting.

The inside distance between the hook's tip and shank. It must be measured during inspection; stretching or opening beyond the manufacturer's limit requires removing the hook from service.

The point where a load's weight is balanced in all directions. Rigging must be arranged so the hook is above this point to keep the load level and stable.

The angle measured between a sling leg and the horizontal load surface. As this angle gets smaller, the tension in each sling leg increases sharply.

The pulling force carried by each sling leg. It increases as the sling angle becomes shallower and must not exceed the sling's rated capacity.

A U-shaped piece of rigging hardware closed with a pin or bolt, used to connect slings to hooks, eyes, or lifting points on a load.

Strands of steel wire twisted into a rope used for hoisting. It must be inspected for broken wires, kinks, corrosion, and wear before each shift.

The process of finding a load's weight before lifting, using shipping papers, markings, calculations from material and volume, or a scale.

Pulling or lifting a load at an angle off the vertical, which places forces on the hoist and structure that were not designed for and can cause failure or load swing.

A sudden application or release of load force, as when a slack sling snaps tight or a load is dropped, producing forces far greater than the static weight.

The pendulum motion of a suspended load after starting or stopping travel. It can strike people or objects and must be controlled with smooth, gradual movements.

A rope attached to a load so a worker standing clear can control rotation and swinging without touching the load.

The handheld control box suspended from the crane by a cable, with pushbuttons for bridge, trolley, and hoist motions. It must be kept dry, undamaged, and clearly labeled.

The closest distance a crane, load, or rigging may come to an energized power line, set by tables based on voltage. It is measured in every direction.

Any place where a body part or object could be caught between moving and stationary parts, such as between the load block and drum or the bridge and runway.

The force wind exerts on a load and crane structure. Large, light, or high-surface loads catch more wind, and lifting must stop when wind exceeds the manufacturer's limit.

A physical barrier or marked boundary that keeps people out of the area beneath and around a suspended load or crane travel path.

The visual and functional checks performed before each shift on hooks, wire rope, controls, limit devices, and runway, with any deficiency corrected or the crane locked out.

The procedure of isolating a crane's power source with a lock and tag so it cannot be energized while someone inspects, repairs, or clears a fault.

Operating each motion, including bridge, trolley, hoist, and each safety device, without a load at the start of the shift to confirm controls and limit devices work.

A prescribed hand movement used by a signal person to direct the operator. Signals are standardized so everyone on the site interprets each motion the same way.

The person assigned to give signals to the operator for a lift. Only one person signals at a time, and the operator follows that person unless anyone gives a stop signal.

A hand signal or verbal command that halts crane motion immediately. Anyone on the site may give it, and the operator must obey it regardless of who is directing the lift.

A control or command that immediately cuts power to crane motions. It is used when a person or property is in danger and must be tested and kept unobstructed.

Placing the crane in a safe resting condition at the end of operation, including landing the load, raising the hook, setting controls to off, and applying brakes and locks.

The condition in which a crane is removed from use because of a deficiency or planned idleness; it is locked, tagged, and reported so no one operates it.