Caterpillar tracked vehicles are now commonly used on building or demolition sites, and can take the form of excavators, diggers, and dumpers, which are designed to operate on steep or uneven terrain. They provide extra traction and stability on muddy or hilly ground, and can be more versatile than wheeled vehicles.
Here’s a look at how tracked vehicles were first invented, and what they were originally used for.
The Hornsby Tractor
The oldest tracked vehicle in the world is the Hornsby Tractor, which is on display at the Tank Museum, in the garrison village of Bovington, near Wareham in Dorset. It is also known as the Little Caterpillar, and it is a steam powered tracked vehicle intended for use in combat terrain.
It was developed by David Roberts, who was originally from Chester, and trained as a hydraulic engineer. In 1895 he joined Richard Hornsby & Sons of Grantham as chief engineer, and by 1904 he rose to the position of managing director.
During his time there, he developed a prototype vehicle which could be used in war situations, in response to a competition held by the War Office in 1903. The brief was to produce a tractor which could haul a load of 25 tonnes for 40 miles, without stopping for fuel or water, and the prize was £1,000.
Hornsby subsequently fulfilled the brief with an 80-horsepower tractor, which beat off all the entrants to achieve 58 miles. This success led Hornsby’s engineers to consider developing a vehicle that could traverse rough and waterlogged terrain, such as might be met on a battlefield.
The first patented caterpillar vehicle
This led to the very first caterpillar tracked vehicle being invented in 1904, and it was patented with this description:
“Two pitched chains of links and pins with cross bars and blocks of metal and wood to make contact with the ground are passed around the front and rear sprocket wheels, one on each side of the vehicle and form a track.”
It continued: “The weight of the vehicle body (and engine) is taken by side brackets provided with curved pathways or bearing surfaces resting on rollers which, in turn, are supported on the chains, or on rollers of large diameter revolving on fixed pins. With this arrangement, when the vehicle is running the body is, so to say, rolled forward on the chains.”
Finally the patent added: “Steering may be accomplished by varying the speed of the driving sprocket wheels on either side of the vehicle.” From this description, it is possible to recognise the tracked vehicles that are still widely used for construction and demolition site jobs, as well as in war situations.
Over the next few years, the design was amended and improved upon, until a version was demonstrated to representatives from the War Office in 1906. It was the original competition winning tractor from 1904, with tracks fitted to it instead of wheels.
The vehicle was subsequently tested in 1907, where soldiers coined the term ‘caterpillar’ to describe the way it moved across the earth. The term caterpillar has been famously adopted by the American Caterpillar company, who produce a wide range of heavy plant machinery, which is used across multiple industries.
In 1909, the War Office ordered the Hornsby tracked vehicle to be produced for military purposes. Four tractors were subsequently delivered to the War Office in May 1910, one of which survives and is on display in the Tank Museum today. It has a 60 horsepower six-cylinder engine, and was used by the British Army until 1914.
The prototype military tank
Most people would automatically think of the tanks that were widely used during WWI as the first tracked vehicles, but in fact the Hornsby Tractor had very little to do with their development.
The first prototype tank was demonstrated by a newly formed Landships Committee in 1915. However, the 14-tonne behemoth could only move at 2mph, and became easily stuck in trenches. This led to further versions being developed, which were more manoeuvrable, but still prone to mechanical failures and overheating.
Whatever the drawbacks of the early tanks, the value of armoured vehicles in combat came to be recognised by military leaders and armies of all nations, and the tank underwent dozens of evolutionary phases and reinventions. They went on to play a key part in battlefield weaponry in WWII, and are still deployed in conflict zones today.
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