High Risk Work Licence - Slewing Mobile Crane C6 (60t) flashcards

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

C6 licence scope

A C6 licence covers slewing mobile cranes with a rated capacity above 20 tonnes up to and including 60 tonnes. It does not cover non-slewing cranes or cranes above 60 tonnes.

Primary duty of care

The person conducting a business or undertaking must ensure health and safety so far as reasonably practicable. Workers must take reasonable care and follow reasonable instructions.

When a SWMS is required

A safe work method statement is required for high risk construction work, including crane work near energised electrical installations, on or near roads, and around tilt-up or precast concrete.

Hierarchy of control

Controls ranked from most to least effective: eliminate the hazard, substitute, apply engineering controls, then administrative controls, with personal protective equipment as the last line.

Tail swing crush zone

The counterweight sweeps a radius behind the slew ring as the crane rotates. People must be excluded from that full swept area, not only from under the suspended load.

Dynamic load effects

Wind, centrifugal force from slewing, snatch or shock loading, and rapid hoist or brake application increase the effective load and reduce the capacity available from the chart.

Rated capacity definition

The maximum load a crane may lift in a given configuration, being the lowest of structural capacity, stability against tipping, and any manufacturer configuration limit.

Net capacity calculation

Net capacity equals the chart rated capacity minus the weight of everything below the hook, such as the hook block, slings, shackles, and spreader beams.

Working radius measurement

The horizontal distance from the crane's slew centre to the vertical line through the load's centre of gravity, measured at the actual working position, not to the boom tip.

Pick-and-carry charts

Separate, much lower capacity charts apply when travelling with a suspended load. They require a level prepared route, correct tyre pressure, and the manufacturer's approved travel configuration.

Sling leg tension formula

Tension per leg equals the load divided by the number of legs, then divided by the cosine of the angle each leg makes with the vertical.

Sling angle effect

As the angle from vertical increases, leg tension rises. At 30 degrees each leg carries about 1.15 times its share; at 45 degrees about 1.41; at 60 degrees about 2.0.

Choke hitch derating

A choke hitch reduces a sling's working load limit, commonly to about 80 percent of its vertical rating. Basket and multi-leg configurations also change the effective working load limit.

Steel mass estimate

Steel has a density of about 7850 kilograms per cubic metre. Concrete is about 2400 and water 1000 kilograms per cubic metre, useful for estimating unknown loads.

Centre of gravity rule

The load's centre of gravity should sit below or aligned with the hook. An offset centre of gravity causes tilt, unequal leg loading, and possible load slip.

Outrigger ground pressure

Ground bearing pressure under an outrigger equals the load that outrigger carries divided by the effective pad area. Larger spreader pads reduce pressure on the soil.

Unequal outrigger loading

Outrigger loads are not equal. The load-side outriggers carry far more, and the maximum outrigger load usually occurs with the boom over that corner at maximum radius.

Outrigger pad contact

Pads must be level and in full contact with the outrigger float centred on them. The pad must be large enough to prevent punching shear or edge failure.

Pre-start inspection items

Check fluids and leaks, tyres, brakes, steering, outrigger beams and floats, wire rope, sheaves, hook and latch, boom pins and wear pads, and all safety devices.

Wire rope discard criteria

Discard wire rope when broken wires in a lay length or set length exceed the standard's limit, when diameter is reduced, or when strands are broken at terminations.

Defect tagging out

A defect affecting safe operation requires the crane to be tagged out, isolated, and removed from service until repaired and re-verified by a competent person.

Lift plan contents

A lift plan records load weight and centre of gravity, rigging, crane position and configuration, radii, capacity utilisation, ground conditions, exclusion zones, roles, and contingencies.

Capacity utilisation

Planned load divided by the chart capacity at the working radius. A common planning threshold is 75 percent, above which more detailed planning and engineering review are warranted.

Multi-crane lift rules

Each crane's share must be known and within its chart, the load kept level, and one nominated person must direct the lift. No crane may be overloaded.

Trial lift procedure

Lift the load a few centimetres, stop, and check rigging, load stability, brake holding, crane level, and outrigger behaviour before continuing with the full lift.

Single signal person rule

Only one nominated person gives signals to the operator at a time, and the operator obeys that person only. A stop signal may be given by anyone.

Stop signal authority

Anyone on site may give a stop signal. The operator must stop all motion immediately on a stop signal regardless of who gave it.

Radio communication protocol

Agree the channel and call signs, and have the operator repeat each instruction before acting. If radio communication fails, the lift must stop.

Powerline approach distances

Minimum approach distances to overhead powerlines are set by the regulator and network. Common minimums start at 3 metres for low voltage and increase with voltage.

Powerline contact response

If the crane contacts a live line, remain in the cab if safe, warn others away, and let no one touch the crane. If evacuation is needed, jump clear with feet together.

Crane shutdown sequence

Land and secure the load, retract the boom to travel position, stow the jib, retract outriggers fully, set the park brake, and lower attachments as the manufacturer specifies.

Crane transport checks

Verify axle loads and gross mass against permits and vehicle ratings, secure the crane with rated chains or straps, and check route height and width clearances.