CSCS Crawler Crane key terms

A lifting machine mounted on continuous tracks that spread its weight over a large area, allowing it to travel and lift on unprepared ground without outriggers.

A crane boom built as an open framework of steel chords and lacing rather than a solid tube, giving high strength with low weight and allowing sections to be added or removed.

The pin or pins that attach the base of the boom to the crane's revolving bed, forming the pivot point the boom raises and lowers around.

The angle between the boom centerline and the horizontal, measured in degrees; it determines radius and capacity for a given boom length and must be read from the load chart.

A short auxiliary boom fixed to the main boom tip to gain extra height or reach, usually with a much lower capacity than the main boom.

Heavy removable blocks mounted at the rear of the revolving bed to balance the lifted load and reduce forward overturning moment.

An auxiliary counterweight system carried on its own axle or trailer behind the crane, increasing capacity by adding backward moment without loading the tracks.

The load per unit area a crane's tracks impose on the ground, calculated from machine plus load weight distributed over the effective track contact area.

The maximum pressure a soil or surface can safely support without excessive settlement or failure, determined by soil type, moisture, and compaction.

A timber or steel pad placed under tracks to spread load over a wider area, reducing bearing pressure on weak or marginal ground.

The manufacturer's table or graph giving the maximum allowable load for each combination of boom length, boom angle or radius, counterweight, and configuration.

The horizontal distance from the crane's rotation center to the vertical line through the load's center of gravity, measured with the boom and load in position.

The total load value read directly from the load chart before any deductions are made for lifting attachments and rigging.

The allowable load remaining after deducting the weight of hooks, blocks, slings, spreaders, and other rigging from the gross capacity.

The combined weight of all lifting gear below the boom tip, including hook block, slings, shackles, and spreader beams, which must be subtracted from chart capacity.

A manufacturer's table listing weights of optional crane components such as jibs, auxiliary heads, and hook blocks that must be subtracted from chart values.

An instrument system that senses boom length, angle, and load to calculate actual load moment and warn or stop the crane before capacity is exceeded.

A device that prevents the crane from lifting or moving a load beyond its rated capacity by cutting out the dangerous motion functions.

A sensor and switch arrangement that stops hoisting or lowering when the hook block approaches the boom tip too closely, preventing rope and block damage.

An assembly of sheaves and a hook that hangs from the hoist rope, providing multiple rope parts and a lifting point for rigging.

The number of rope falls running between the boom tip sheaves and the hook block, which divides the line pull and determines lifting speed.

The wire rope that runs from the crane's winch drum over boom tip sheaves to the hook block, raising and lowering the load.

The direction and pattern in which strands are twisted around the core, such as regular lay or lang lay, which affects handling, wear, and inspection.

A length of wire rope, chain, or synthetic webbing configured to connect the load to the hook and distribute lifting force.

The angle between a sling leg and the horizontal; as it flattens, tension in each leg rises sharply and must be accounted for in the lift plan.

A multiplier applied to load weight to find actual sling leg tension for a given sling angle, growing larger as the angle becomes shallower.

A U-shaped metal fitting closed by a pin or bolt, used to connect slings, hooks, and attachments; its rated capacity must match the lift.

Collective term for shackles, hooks, links, rings, and swivels used to join lifting components, each marked with a working load limit.

The maximum load a sling, shackle, or other lifting component is rated to carry in a specified configuration, marked on the item by the manufacturer.

A documented visual and physical check of slings for broken wires, cuts, crushing, heat damage, or tag loss before each use and at required intervals.

The walk-around and function check performed before each shift covering fluids, ropes, sheaves, brakes, alarms, and safety devices.

The crane's resistance to tipping, maintained when the overturning moment from the load stays below the restoring moment from the machine and counterweight.

The turning force produced by the load weight multiplied by its horizontal distance from the tipping point, which the crane's own weight must resist.

Any force applied sideways to the boom, such as dragging a load or swinging too fast, which can buckle the boom and is prohibited unless charted.

The brake that holds the upper structure from rotating; it must be applied when parked and released smoothly to control load swing.

A rope attached to the load and held by a helper on the ground to control rotation and swinging without the person touching the load.

Standardized arm and hand movements used by a designated signal person to direct crane motions when voice or radio communication is impractical.

A qualified individual who directs the operator's movements by hand signals, radio, or other agreed means and is the only person the operator obeys.

A lift judged high risk because of load weight, configuration, personnel exposure, or nearby hazards, requiring a written plan and additional supervision.

A written document prepared before a lift that identifies the load, rigging, crane configuration, capacity calculations, ground conditions, and responsible persons.

The area beneath and around a suspended load kept clear of all personnel except those essential to the lift, marked and enforced by barriers or spotters.

The circular area swept by the counterweight and boom as the crane rotates, which must be kept clear of people, structures, and equipment.

The minimum safe distance kept between any part of the crane or load and energized overhead lines, set by voltage and regulation.

The route a crawler crane takes on site, which must be surveyed for slope, soft spots, underground services, and bearing capacity before moving.