NCCO key terms

The horizontal distance from the crane's center of rotation to the load's center of gravity, measured with the boom or jib positioned for the lift. It directly drives rated capacity.

A manufacturer-issued table or diagram showing the maximum allowable load for a crane at each combination of radius, boom length, and boom angle under stated configurations and conditions.

The maximum load a crane may lift in a specific configuration, as published by the manufacturer after applying structural and stability limits. It is the starting point for deductions, not the final allowable load.

The rated capacity reduced by the weight of all lifting attachments and rigging, including hook block, slings, shackles, and spreader beams, giving the maximum payload the crane may safely lift.

The total weight suspended from the crane's boom or jib, comprising the payload plus all rigging, lifting devices, and attachments below the boom tip connection point.

Weights subtracted from the published rated capacity for items such as hook block, slings, shackles, jib, and auxiliary head, ensuring the chart value is not exceeded by the actual suspended load.

The product of a load's weight and its horizontal distance from the tipping axis or crane rotation center. Mobile crane stability is governed by comparing load moments against the counterweight moment.

An electronic system that senses boom angle, length, and pressure to compute load moment and warn or stop the operator before rated capacity is exceeded, when properly calibrated and configured.

A device that prevents lifting or moving loads beyond the rated capacity for the current configuration by interrupting the dangerous function, distinct from a warning-only indicator.

A sensing system that stops hoisting up or boom lowering when the hook block approaches the boom tip, preventing contact that can snap wire rope and drop the load.

The condition in which the hook block or headache ball contacts the boom tip sheave assembly, potentially parting the hoist rope and releasing the load. It is prevented by the anti-two-block device and operator awareness.

A crane's resistance to tipping about its outriggers, crawlers, or wheels, determined by counterweight, ground bearing, levelness, and the relationship between load moment and resisting moment.

The force per unit area a crane's outrigger or track imposes on the supporting surface. It must be compared with soil capacity, and spread mats or cribbing added where the surface is inadequate.

Cribbing, mats, or pads placed under outrigger floats to spread load over a larger area and keep the crane level. Blocking must be sized for the actual ground pressure and be structurally sound.

Setting the crane so its upperworks and carrier are within the manufacturer's specified tolerance, usually checked with a bubble level, before extending outriggers and lifting. Out-of-level conditions reduce capacity.

The process of identifying hidden underground features such as basements, tanks, utility vaults, or culverts beneath outriggers or tracks, typically by drawings, probing, or ground-penetrating radar before setup.

A pre-lift walk-down identifying power lines, excavations, slopes, traffic, pedestrians, overhead obstructions, and other conditions that affect crane setup and the lift plan.

A marked or barricaded area beneath and around the load path and swing radius where personnel are prohibited during lifting, protecting them from dropped loads, swing hazards, and pinch points.

A lift meeting defined criteria such as exceeding a set percentage of rated capacity, using multiple cranes, lifting personnel, or involving unusual risk, requiring an engineered lift plan and additional review.

A documented description of a lift including load weight, rigging, crane position, radii, capacity calculations, ground conditions, personnel roles, and contingencies, prepared and reviewed before work begins.

A briefing of all personnel involved before a lift, covering the lift plan, roles, signals, hazards, and emergency actions, ensuring shared understanding of the sequence and stop-work authority.

A person who meets the employer's and applicable standard's requirements to direct crane movements, demonstrates knowledge of signals, and is competent to give clear, correct directions to the operator.

Standardized arm and hand movements used to direct crane motions when voice or radio communication is unavailable or unreliable, agreed upon before the lift and used by one designated signal person.

A signal any worker may give to halt crane movement immediately when danger is perceived. The operator must obey it regardless of who gives it and stop until the situation is resolved.

The right and responsibility of any worker to halt a lift or crane operation they believe is unsafe, without fear of reprisal, until the concern is addressed by a competent person.

A rope attached to a load to control rotation and swing from a distance, keeping handlers outside the crush zone. Tag lines must not be wrapped around hands or used to arrest a swinging load.

Sudden application or release of load force, as when a load is jerked from the ground or caught during a swing, producing dynamic forces that can far exceed static weight and overload rigging or crane.

Additional force on rigging and crane structure caused by acceleration, deceleration, wind, or load movement during a lift, accounted for by design factors and smooth operating technique.

A multiplier reflecting increased tension in sling legs as the angle between the leg and horizontal decreases. Shallower angles raise leg tension sharply, so capacity falls as the angle flattens.

The force carried by each sling leg, calculated from load weight, number of legs, and vertical angle. It must not exceed the sling's rated capacity for the hitch and configuration used.

The maximum mass or force a rigging component is authorized to support in a specific application, as assigned by the manufacturer or standard, after applying design and service factors.

A test load applied to rigging hardware or a crane component to verify strength and detect defects, typically above the working load limit but below the component's breaking strength.

The method of attaching slings to a load, such as vertical, choker, basket, or bridle. Each hitch changes the effective capacity and the way load forces act on the sling.

The point at which a load's weight is considered concentrated. Its location relative to the hook determines load balance, sling tension distribution, and whether the load will tilt when lifted.

Maintaining a load's position and orientation during lifting through proper rigging, tag lines, and smooth crane movements, preventing swinging, rotation, and impact with structures or personnel.

A documented examination of hoist and boom ropes for broken wires, corrosion, kinking, birdcaging, and diameter loss, with removal criteria defined by the manufacturer and applicable standards.

A check performed by the operator before each shift covering fluid levels, tires, outriggers, hooks, latches, wire rope, limit devices, alarms, and controls, with defects corrected or reported before use.

A more thorough examination at defined intervals, often by a qualified inspector, covering structural members, mechanisms, brakes, and safety devices, with results recorded and deficiencies tracked to correction.

Operating each crane motion and safety device through its range without a load to confirm correct response, including limit switches, brakes, and warning systems, before beginning production lifting.

A person capable of identifying existing and predictable hazards and authorized to take prompt corrective action, as defined in applicable safety standards for inspections and rigging decisions.

A person who, by possession of a recognized degree, certificate, or professional standing, or by extensive knowledge and experience, has demonstrated ability to resolve problems relating to the subject work.

Duties including inspecting the crane, verifying load weight and configuration, obeying signals from the designated person, refusing unsafe lifts, and stopping work when conditions change adversely.

Force exerted on the crane and load by wind, increasing with sail area and gust speed. Manufacturers set maximum wind speeds for operations, and loads with large surface area need special assessment.

A lift using two or more cranes to handle one load, requiring an engineered plan, defined load sharing, communication, and recognition that capacity charts do not directly cover the shared condition.

The minimum distance kept between any part of the crane, load, or rigging and energized overhead lines, as specified by applicable standards, with de-energizing or barriers used where approach is unavoidable.