H. E. Merritt

Henry Edward Merritt MBE (20 May 1899 – 28 March 1974) was a British mechanical engineer who invented the Merritt–Brown triple differential tank transmission that provided greater manoeuvrability to a generation of British tanks, starting with the Churchill in 1939 and continuing into the 1980s. It allowed a tracked vehicle to change direction while on the move with less loss of power than under other steering systems, and to perform a neutral turn on the spot by rotating its tracks in opposite directions. Merritt's invention suited the faster pace of tank warfare of the Second World War, which contrasted with the more static trench warfare of the First World War, for which earlier generations of British tanks had been optimised.

He wrote a number of books, including the standard texts Gears (1942), which received three editions, and its companion volume Gear Trains (1947), which included a Brocot table derived from the work of the French clockmaker and mathematician Achille Brocot.^[1]

He complained that gearing was a field dominated by empiricism in which science had so far played little role, so that it had hardly progressed in 150 years, but Brian Hayes found sophisticated mathematical concepts in use in the field and, for him, a surprising degree of interchange between mathematics and mechanics. By 2000, many of the problems that Merritt had wrestled with had been solved through the application of brute-force calculations by computers.