Mobile Crane Operation
Mobile Crane Operation: Setup, Inspection, and Shutdown
This domain tests the sequence that turns a crane into a stable lifting machine: pre-operation inspection, site preparation, outrigger setup, operational checks, and orderly shutdown. The exam favors the order of events and the conditions that must be true before a load leaves the ground.
Core rules
- Complete a shift inspection before use: fluids, leaks, tires, brakes, steering, wire rope, sheaves, hooks, outrigger beams and pads, alarms, and safety devices.
- Verify the load chart and configuration match the crane as set up. Never bypass the load moment indicator, anti-two-block device, or outrigger monitoring system.
- Prepare the ground before extending outriggers. Use mats or floats sized to spread outrigger reactions; keep pads clear of backfilled, thawed, or utility-covered ground.
- Extend outriggers fully and level the crane within the manufacturer tolerance. Recheck level after loading and during the lift.
- Barricade the swing radius and keep personnel clear of the counterweight path.
- At shutdown, land the load, retract boom and outriggers per the manufacturer, set the parking brake, chock if required, and secure controls.
Worked example
An outrigger reaction is 40,000 lb on a 4 ft by 4 ft pad. Pad area is 16 ft2, so bearing pressure is 40,000 divided by 16, or 2,500 lb/ft2. If the prepared soil is rated at 2,000 lb/ft2, the pad is too small. A 5 ft by 5 ft pad gives 25 ft2 and 1,600 lb/ft2, which is acceptable, but the mat must also be structurally adequate. The reasoning is to compare pressure to soil capacity, not to the crane gross weight.
Traps
Assuming outriggers make ground condition irrelevant; leveling only with the outriggers; skipping the post-setup function test; and treating a shift inspection as a substitute for periodic inspection.