Knox progressively improved their models, moving the engine from under the seat to up front under a bonnet and going from chain-driven to shaft-drive. In 1908 a water-cooled four-cylinder engine was introduced and customers could choose air-cooled or pay $100 more for water-cooled models. A six-cylinder engine became available in 1910 and all Knox's became water-cooled. Only luxury-priced Knox's were offered after 1910. Racing The Knox was raced by Billy Bourque in the 1909 AAA Championship Car race at the Indianapolis Motor Speedway. In 1910 a Knox was driven by Fred Belcher in the Vanderbilt Cup race. Fate By 1912 Knox sales were slipping and a receiver was called in. The last Knox automobiles were built in 1914 and Knox was declared bankrupt in 1915. Knox reorganized as the Knox Motors Corporation and continued build tractors and trucks until 1924. Afterwards Harry Knox moved on to design tanks for the US Army Ordnance Department; his T1 Light Tank wasn't adopted, but his Vertical volute spring suspension and his track design were used on almost all American tanks of the WWII, and he designed its replacement HVSS, which served until 1980s in some countries, as well. Gallery Knox Models Knox Production References See also Brass Era car List of defunct United States automobile manufacturers Knox automobiles at ConceptCarz Defunct motor vehicle manufacturers of the United States Defunct manufacturing companies based in Massachusetts Luxury motor vehicle manufacturers Brass Era vehicles Veteran vehicles 1900s cars 1910s cars History of Springfield, Massachusetts Manufacturing companies based in Springfield, Massachusetts American companies established in 1900 Vehicle manufacturing companies established in 1900 Vehicle manufacturing companies disestablished in 1924 1900 establishments in Massachusetts 1924 disestablishments in Massachusetts Motor vehicle manufacturers based in Massachusetts American companies disestablished in 1924 Cars introduced in 1900