Site and Ground Conditions, Setup, and Stability
Crawler cranes spread load over track contact area, but bearing pressure still depends on the crane's weight plus load, the counterweight, and the boom geometry. Candidates must understand ground bearing pressure, outrigger mats or crane mats, flotation, slope, and underground hazards such as utilities, vaults, septic fields, and recently backfilled trenches. A level crane is a stability requirement, not a convenience; most manufacturers limit levelness to about 1 percent (roughly 1 degree) unless the manual states otherwise.
Stability has two modes: backward stability (boom over the rear, counterweight side) and forward or load-side stability. The chart's capacity is generally controlled by strength or tipping, whichever is lower, and the chart already includes a margin. Traps include assuming mats increase chart capacity (they do not; they only improve bearing), assuming a larger counterweight always helps (it can reduce capacity in some configurations and hurts backward stability), and ignoring wind, which acts on the boom and load and can cause backward tipping when a load is suddenly released.
Setup checks include leveling the carbody, verifying track extension or retraction per the chart, installing the correct counterweight, confirming boom hoist pendants and pins, and checking that the swing area is clear. Soft ground under one track causes the crane to tilt toward the load, effectively increasing radius and reducing capacity.
Worked rule of thumb: if one track sinks 2 inches over a 12-foot track gauge, the crane tilts about 1 degree, which is at the typical limit. Stop, improve the ground, and re-level before lifting.