Crawler Crane

Overview

A crawler crane is a heavy lifting machine mounted on a pair of crawler tracks instead of wheels. Because the tracks spread the load over a large area, it can pick and carry heavy loads, travel with a load suspended, and work on prepared but unpaved ground without outriggers. Its lattice boom, a bolted or pinned steel truss, is light for its length and can be built up in sections to reach great heights, making the type a staple of bridge, power-plant, wind, and high-rise construction.

The machine splits into a travelling Crawler Undercarriage, a slewing upper carried on the Slewing System, and the Lattice Boom with its hoist winches.

How it works

The Crawler Undercarriage carries the carbody, two crawler side frames, and travel drives; carbody Carbody Counterweight slabs lower the centre of gravity. The Rotating Frame (Revolving Deck) sits on a large slewing bearing in the Slewing System, so the entire upper structure can rotate 360°. On the rotating frame sit the Diesel Engine diesel, the winches, and a Machinery House enclosure, balanced at the rear by Upper Counterweight Slab slabs.

Three winches do the lifting. The Boom Hoist Winch reels pendant lines over the Gantry (A-Frame) A-frame to raise and lower the boom angle; the Main Hoist Winch and Auxiliary Hoist Winch run rope down the boom to the Hook Block, whose multiple sheaves multiply line pull into lifting capacity. Load charts limit the safe load for each boom length and radius.

The operator works from the Operator Cab with load-moment indication, while the Electrical System system handles control, monitoring, and starting power. Capacity falls sharply as the load radius increases, so rigging plans match boom configuration and counterweight to each lift.