track

Continuous track is a system of vehicle propulsion used in tracked vehicles, running on a continuous band of treads or track plates driven by two or more wheels. The large surface area of the tracks distributes the weight of the vehicle better than steel or rubber tyres on an equivalent vehicle, enabling continuous tracked vehicles to traverse soft ground with less likelihood of becoming stuck due to sinking.
Modern continuous tracks can be made with soft belts of synthetic rubber, reinforced with steel wires, in the case of lighter agricultural machinery. The more common classical type is a solid chain track made of steel plates (with or without rubber pads), also called caterpillar track or tank tread, which is preferred for robust and heavy construction vehicles and military vehicles.
The prominent treads of the metal plates are both hard-wearing and damage resistant, especially in comparison to rubber tyres. The aggressive treads of the tracks provide good traction in soft surfaces but can damage paved surfaces, so some metal tracks can have rubber pads installed for use on paved surfaces. Other than soft rubber belts, most chain tracks apply a stiff mechanism to distribute the load equally over the entire space between the wheels for minimal deformation, so that even heaviest vehicles can move easily, just like a train on its straight tracks.
The idea of continuous tracks can be traced back as far as the 1830s, however, the stiff mechanism was first introduced by Hornsby & Sons in 1904 and then made popular by Caterpillar Tractor Company, with tanks emerging during World War I. Today, they are commonly used on a variety of vehicles, including snowmobiles, tractors, bulldozers, excavators and tanks.

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