NZ Certificate in Cranes flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Rated capacity

The maximum load a crane may lift at a stated radius, boom length and configuration, as published in the manufacturer's load chart. It is never increased by the operator.

Load moment

Load multiplied by radius from the slewing centre. Crane stability is governed by load moment, so increasing radius reduces allowable load even when the load mass is unchanged.

Anti-two-block device

A safety device that prevents the hook block from contacting the boom head. It stops the hoist function when the two parts approach each other, preventing rope and structural damage.

Rated capacity limiter

An instrument that measures load, radius and configuration and warns or stops the crane before the load chart is exceeded. It supplements, but does not replace, the operator's judgement.

Duty classification

A grouping of cranes by state of loading and class of utilisation, defined in AS 2550.1 and ISO 4301. It sets design life, inspection intervals and maintenance requirements.

Slewing side load

The horizontal force induced on a boom when a suspended load is accelerated or decelerated during slewing. It adds to the structural load and must stay within the chart allowance.

All-terrain crane

A mobile crane on a truck-style chassis with multiple steering modes and road travel capability, combining high road speed with rough-site mobility and a telescopic boom.

Rough-terrain crane

A mobile crane with a single cab, four-wheel drive and large tyres, designed for off-road site work. It cannot travel on public roads without permits and transport.

Luffing jib tower crane

A tower crane whose jib pivots up and down rather than slewing horizontally. It suits confined sites because the working radius changes without a large tail swing.

Outrigger configuration

The extension and spread of outrigger beams and pads. Full, partial and asymmetric extension each have their own load chart, and interpolation between them is not permitted.

Ground bearing pressure

The pressure a crane imposes on the ground through outrigger pads or tracks, calculated as total weight divided by total contact area. It must not exceed the verified allowable bearing pressure.

Counterweight

Mass fitted to the rear of the superstructure to counterbalance the load moment. It must match the configuration stated in the load chart used for the lift.

Complex lift

A lift requiring a documented plan by a competent person because of load, radius, ground or site conditions. It is one of the routine, complex and high-risk lift categories.

Capacity utilisation

Required capacity divided by rated capacity at the governing radius, expressed as a percentage. It is the key measure compared against site and plan limits.

Governing radius

The largest radius the load reaches along its path, combined with the heaviest load. It sets the capacity case that controls the whole lifting plan.

Trial lift

Lifting the load just clear of the ground to confirm balance, rigging behaviour and crane response before committing to the full lift path.

Dynamic allowance

An addition to the static load to account for hoisting acceleration, slewing, travelling and shock loading. It is applied when checking capacity and ground bearing pressure.

Sling leg tension

The force in one leg of a multi-leg sling, calculated as the load share divided by the cosine of the leg angle from vertical. Tension rises sharply as the angle increases.

Sling angle factor

A multiplier applied to sling capacity based on angle from horizontal: 1.000 at 90 degrees, 0.866 at 60, 0.707 at 45 and 0.500 at 30. Lower angles reduce capacity.

Centre of gravity

The point through which the load's weight acts. For a stable lift it must sit directly below the hook, otherwise the load tilts and redistributes force between sling legs.

Choker hitch

A sling passed around the load and through its own eye. It grips the load but derates capacity to roughly 75 to 80 percent of the sling's vertical rating.

Basket hitch

A sling passed under the load with both eyes on the hook. It can achieve up to twice the single-leg vertical rating, provided the bend radius is adequate.

Tag line

A rope attached to the load so a handler can control rotation and swing from outside the drop zone. It must never be wrapped around a hand or body.

Exclusion zone

The area beneath and around the load's path and potential drop, kept clear of people. Its radius is set by the load and swing, not by the crane base.

Hook throat opening

The gap of the hook. A hook is removed from service when the throat opening exceeds 10 percent of its original dimension, or when it is twisted more than 10 degrees.

Wire rope discard criteria

Conditions requiring removal of a wire rope, including broken wires in a set length, diameter reduction, corrosion, kinks, bird-caging and heat damage, per AS 3569 and ISO 4309.

Stop signal rule

Any person may give a stop signal to the crane operator, and the operator must obey it immediately. Only one designated dogger gives the working signals.

Pre-start inspection

The operator's daily check of tyres, outriggers, fluids, wire rope, hooks, brakes, limit switches, alarms and safety devices before the crane is used.

Rigging system WLL

The working load limit of the complete rigging assembly, which equals the lowest-rated component in the system, including slings, shackles, hooks and master links.

Side pull prohibition

Dragging or pulling a load sideways imposes forces the crane is not rated for. Loads are lifted vertically unless the manufacturer's chart expressly permits otherwise.

Load-holding valve

A valve in a hydraulic circuit that prevents the load from dropping if a hose fails or pressure is lost. Its function is verified during maintenance and inspection.

Load test certificate

Documentation recording a test at rated capacity after major repair or alteration, with the test load, method and witnesses. It verifies the crane's capacity before return to service.