Pre-operational inspection, set-up, stabilisers and ground conditions
Pre-operational inspection is a documented routine. Walk around the crane checking structure for cracks and deformation, welds, pins and retainers, rope for broken wires, kinks, corrosion and correct spooling, hook for throat opening, wear and latch function, brakes, clutches, hydraulics for leaks, tyres or tracks, lights, alarms, limiters and the rated capacity indicator. Test controls and safety devices in a clear area before lifting.
Set-up is where many incidents begin. Establish ground bearing capacity. Use the manufacturer's outrigger loadings and spread the load with mats or spreader beams sized for the pressure. Keep outriggers clear of excavations, trenches, backfilled areas, drains and underground services. Level the crane within the manufacturer's tolerance. Fully extend outriggers as specified, fit pins and floats, and confirm the bubble or level indicator. Consider slope, wind exposure and access.
Traps: assuming compacted fill is adequate, using undersized dunnage, setting up over services, failing to level, and skipping the function test after set-up. Another trap is relying on the previous operator's inspection.
Rule of thumb: no lift until the crane is level, outriggers are on competent ground with adequate spread, and safety devices are proven. Worked example: an outrigger loading of 40 t on a 1 m by 1 m mat gives 40 t per square metre; if the ground capacity is 25 t per square metre, enlarge the mat to at least 1.6 square metres or relocate.