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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.
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 force per unit area 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.
A long line of 'patent' disputes exist as to who the "originator" was of this concept.
After Lombard began operations, Hornsby in England manufactured at least two full length "track steer" machines, and their patent was later purchased by Holt in 1913, allowing Holt to be popularly known as the "inventor" of crawler tractors. Since the "tank" was a British concept it is more likely the Hornsby, which had built and unsuccessfully pitched to the British military, was the inspiration.
In a patent dispute involving rival crawler builder Best, testimony was brought in from people including Lombard, that Holt had inspected a Lombard log hauler shipped out to a western state by people who would later build the Phoenix log hauler in Eau Claire, WI, under license from Lombard. The Phoenix Centipeed typically had a fancier wood cab, steering wheel tipped forward at a 45 degree angle and vertical instead of horizontal cylinders.
Holt and Best ended up merging. Holt had registered the trademark Caterpillar. They merged company produced a version of the Best 60 tractor, which later became the Caterpillar 60. The new corporation Caterpillar Inc. took that name about 1925, and remains in business today.
Modern 'Rubber' TracksEdit
The invention of the modern rubber track lead to various other innovative design ideas.
The modern rubber tracked crawler tractor The quad-track tractor, High horse power high traction, low ground pressure.