NCCCO Tower Crane key terms

The engineered concrete footing, piles, or ballast base that transfers the crane's weight and lifting forces into the ground. Its design is set by the manufacturer and a qualified engineer, not by the operator.

Heavy blocks or weights placed on the crane base to resist overturning. The amount and position must match the manufacturer's chart for the crane's height and jib configuration.

Embedded threaded rods or cast-in anchors that fasten the base section to the foundation. They must be the correct size and grade, tightened to the specified torque, and inspected for damage before erection.

The load per unit area that the soil or slab must carry beneath the crane foundation, mats, or blocking. If it is exceeded, the crane can settle, tilt, or overturn.

The measured out-of-plumb of the erected tower. The manufacturer sets a tolerance; exceeding it adds loads to the crane and must be corrected before the crane is put into service.

Buried pipes, cables, and voids that are located and marked before excavation or foundation work, so digging and crane loads do not damage them or leave the base unsupported.

The measured gap between any part of the rotating crane, including the jib and counter-jib, and nearby buildings, power lines, or other cranes. It must be confirmed for the full slewing circle.

A steel lattice or tube segment that stacks to form the crane tower. Sections are bolted or pinned together and pass all vertical and overturning loads down to the foundation.

The bearing and drive assembly between the top of the mast and the turntable that allows the upper works to rotate. It carries vertical, moment, and horizontal loads.

The long horizontal working arm that carries the trolley and hoist rope. Its length sets the maximum working radius and must match the configuration used for the load chart.

The shorter arm opposite the jib that holds counterweights and often the hoist machinery. Its weights balance the jib and must be installed exactly as the manual specifies.

A steel collar with hydraulic rams that supports the upper works while new mast sections are added, letting the crane raise itself as the building rises.

A structural connection that fastens the mast to the building at a set height. Ties increase the crane's free-standing capacity and resist wind and operating loads; spacing comes from the manufacturer or engineer.

The greatest tower height a crane can support with no ties to a structure, stated in the manufacturer's data. Adding mast beyond it without ties can overload the crane.

The qualified person who directs erection, climbing, and dismantling. This person verifies each step against the manufacturer's instructions and confirms stability before releasing the crane for work.

A documented check of every component before assembly: pins, bolts, welds, ropes, sheaves, and safety devices. Damage or missing parts are found while the crane is still on the ground.

The manufacturer's table or diagram showing the maximum capacity at each working radius, jib length, and configuration, under stated conditions. It is the controlling limit for every lift.

The horizontal distance from the crane's slewing center to the center of gravity of the suspended load. Capacity drops as the radius grows.

The greatest load the crane may lift at a stated radius and configuration, after the weight of hook block, slings, and other below-the-hook gear has been deducted.

The load multiplied by its working radius. The crane's moment limiter compares this figure to the rated moment and stops movements that would exceed it.

The angle a sling leg makes with the horizontal. Flatter angles sharply raise tension in each leg, so the rated capacity of the sling is reduced.

The point at which a load's weight balances. The hook should hang directly above it so the load stays level and does not shift during the lift.

The number of rope falls between the jib tip and the hook block. More falls increase capacity but slow hoisting, and the load chart states which reeving is assumed.

A U-shaped connector with a pin that joins slings, hooks, and fittings. Its working load limit, pin type, and alignment must be checked before use.

A spring-loaded device that closes the hook throat so slings and fittings cannot slip off. A missing or damaged latch puts the hook out of service.

The wheeled carriage that runs along the jib and carries the hoist rope and hook. Moving the trolley in or out changes working radius and therefore capacity.

Rotating the crane's upper works around its vertical axis. It must be done slowly with the load controlled, since swinging a load creates side loads and pendulum swing.

A rope tied to the load and handled by a worker outside the fall zone, used to keep the load from spinning or swinging while it is hoisted and landed.

A qualified worker who directs the operator using standard hand, voice, or radio signals. The operator follows that person's signals and stops when a signal is unclear.

A written description of a lift covering load weight, rigging, crane position, capacity check, ground conditions, personnel, and contingencies. It is prepared and reviewed before work starts.

A lift that is unusually heavy, near the crane's capacity, over people or structures, or made with more than one crane. It needs engineering review and a documented plan.

The ground area swept by the jib, counter-jib, and load as the crane rotates. It must be barricaded or controlled so no one is struck or caught between crane and structures.

A sensor and switch that stops the hoist before the hook block contacts the jib tip. Without it, the rope can break and the load can drop.

An automatic system that measures load and radius and stops or restricts crane motions as the rated moment is approached, preventing structural overload.

Electronic sensors and software that warn or stop cranes before their jibs, trolleys, or loads strike each other or fixed obstacles, common on shared or congested sites.

A wind-speed sensor mounted on the crane that gives a continuous reading. Lifting stops when the measured wind reaches the limit in the manufacturer's manual.

The walk-around and function check the operator performs at the start of each shift, covering structure, ropes, hook, brakes, limiters, and alarms, with results recorded.

A thorough documented inspection at intervals set by the manufacturer and regulations, often by a qualified inspector, covering structural welds, pins, bolts, and safety devices.

Examining hoist rope for broken wires, kinks, corrosion, crushing, and wear, then comparing findings to the removal criteria; rope that fails must be replaced before use.

A key-operated switch that bypasses a limiter for a specific manufacturer-approved purpose. Using it to defeat a safety device during normal lifting is prohibited.