Site Setup and Inspection
Site setup and inspection for a lattice boom crawler crane starts with the ground, not the machine. The crane's rated capacity assumes the crane is level and supported on firm, stable ground; if the ground yields, the chart no longer applies. Estimate ground bearing pressure by dividing the total weight of crane, counterweight, attachments, rigging, and load by the effective bearing area of the tracks or mats. Compare that to the soil's allowable bearing capacity and use mats or cribbing to spread the load when needed. Confirm level within the manufacturer's tolerance (often about 1 percent) and check for slopes, soft spots, excavations, underground utilities, and drainage. Plan the swing radius, barricades, access, assembly area, and clearance from power lines.
Pre-shift inspection covers wire rope, sheaves, drums, boom sections, pins and retainers, tracks, brakes, clutches, hydraulic lines, and safety devices: load moment indicator or rated capacity limiter, anti-two-block, boom angle indicator, level, horn, and fire extinguisher. Know wire rope removal criteria-broken wires, kinks, crushing, corrosion, diameter loss, and damaged end fittings. Frequent inspections are required at intervals, and periodic inspections are more thorough; follow the manufacturer and applicable standard.
Traps: treating mats as a way to increase chart capacity rather than only improve ground support; accepting 'close enough' level; inspecting the crane but not the ground; missing pins or retainers after assembly; trusting an LMI that has not been set for the actual boom or jib configuration; and letting a damaged rope run to the end of the shift.
Rule of thumb: if calculated ground pressure is 8,000 psf and the soil is rated 4,000 psf, doubling the mat area halves the pressure-but only if the mat is stiff enough to distribute load and the ground beneath is uniform.