Crawler Tractor

A Crawler tractor (also called: track-type tractor, tracked vehicle, or track-laying vehicle) is a vehicle that runs on tracks instead of wheels.   Typically used as part of an Engineering vehicle once additional attachments have been added, such as a bulldozer blade, or a ripper. 

The walking device is composed of a guide wheel, a follower wheel, a support wheel, a driving wheel and a track. During operation, the driving wheel rotates around the track, and the supporting wheel rolls forward or backward on the track of the track.

For Farm use usually fitted with a 3-point linkage for fitting Mounted implements.   But most earlt machines just used trailed implements attached to the drawbar.The principal design advantages of tracked over wheeled vehicles are that they are in contact with a larger surface area than would generally be the case with a wheeled vehicle, and as a result exert a much lower 'Ground Pressure' on the ground being traversed than a conventional wheeled vehicle of the same weight. This makes them suitable for use on soft, low friction and uneven ground such as mud, ice and snow.   The principal disadvantage is that tracks are a more complex mechanism than a wheel, and relatively prone to failure modes such as snapped or derailed tracks.

Other versions are fitted with attachments such as scraper boxes, or side mounted jibs and large counter weights to lift long lengths of pipe lines for installation, usually working in groups.