The first and original 'Caterpillar' or 'walking' engine made by R. Hornsby & Sons of Grantham. R. Hornsby & Sons grew into a major manufacturer of agricultural machinery, at their Spittle Gate Works. The firm went on to produce steam engines used to drive threshing machines and other equipment such as traction engines; their portable steam engine was one of their most important products and the market leader. Later a chain-track was added to an oil-engined tractor: the caterpillar t