Crane Types, Components, and Terminology
A crawler crane carries its load on a tracked undercarriage, so it can travel with a load under strict limits but cannot pick and carry like a mobile crane on outriggers without a chart that expressly permits it. Candidates must know the load path: load, hook block and hook, slings, boom tip (with or without jib), boom sections and inserts, boom foot pins, boom hoist (pendants or luffing cylinders), mast or gantry, upperworks, swing bearing and swing drive, carbody, crawler frames, tracks, and counterweight. Distinguish boom length from radius from boom angle; radius is measured horizontally from the crane's center of rotation to the load's center of gravity, not to the boom tip.
Terminology traps are common. Rated capacity is the chart value before deductions; gross capacity and net capacity differ by the weight of hook block, slings, and any stowed jib or auxiliary head that must be deducted. Parts of line determine the load per line and the line pull; more parts reduce line pull but add friction and block weight. Boom point and jib are not interchangeable. Counterweight and carbody counterweight are separate items, and some charts require them removed for certain configurations.
Worked rule: net capacity = chart capacity minus all lifting gear below the boom tip (hook block, slings, shackles, spreader). If a chart shows 24,000 lb at a given radius and the hook block and rigging weigh 1,800 lb, the allowable load is 22,200 lb. Never add capacity for favorable conditions; charts already assume level ground and no wind unless footnoted.
Also know crawler-specific components: track shoes and grousers, drive sprocket, idler, track rollers, and the swing lock or house lock used for travel.