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David Brown Restoration By Peter Williams, David Brown Parts Ltd reverse manual gearbox. It was fitted to experimental tractors based on the then current 1200. It worked well, except that test drivers reported a lack of power, due to the energy absorbed by the transmission. A simple answer was to increase the power by adjusting the fuel pump, though test driver Mike Funnel rather overdid this on one tractor, resulting in a broken crankshaft! The experimental department fitted a new crankshaft and tested the engine, finding that the output had been increased from the standard 72 H.P. as fitted to the 1200, to over 90 H.P. Mike Funnel says that he was surprised to escape dismissal due to this act! From then on, David Brown did concede to increase the power, but by a more moderate amount. The starting point
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lutch-less transmissions are now the norm on many vehicles, but before this innovation most tractors could only carry out work in the gear that they were capable of starting from a standstill in. Both John Deere and Ford had offered clutch-less transmissions to enable changing gear whilst on the move, under load, in the 1960’s. Neither had been widely accepted, partly due to the power losses involved. Others, including Massey Ferguson, offered a simple, clutch-less “High” and “Low” facility on each conventional gear, which whilst useful, was limited in its scope. Meanwhile, building on their experience of making tank transmissions, David Brown had been experimenting with “Autodrive” (a fully automatic transmission) on a 990 Implematic but this never reached production. However, a traditional British compromise rose out of its ashes in 1971. Dubbed “Hydrashift”, it provided 4 clutch-less changes on every gear in a 3 forward 1
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The system met with widespread approval and went on to win a Queen’s Award to industry. The more powerful 1412 tractor followed with this transmission, then it was offered as an option on the larger models from the 90 series that was introduced in 1979. The subsequent 7 final series of tractors to be built at the Meltham, Yorkshire factory were the 94 series, now branded as “Case”. Now, Hydrashift was also made available on 4 wheel drive tractors. Indeed, the largest in the range, the 4 wheel drive 1694 was only available with Hydrashift. With only 1,200 built, it is now very collectable. During the following years this format was copied and refined by virtually every other tractor manufacturer until gradually being superceded by “constantly variable” transmissions. With the 50th Anniversary of this innovation in mind, I set about the restoration of what is probably the earliest surviving David Brown incorporating this transmission, a 1212. Built in April 1970, it was the 12th one built, as a pre-production tractor, ahead of the official launch the
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