Self-Changing Gears

Self-Changing Gears was a British company, set up and owned equally by Walter Gordon Wilson and John Davenport Siddeley to develop and exploit the Wilson or pre-selector gearbox. Self-Changing Gears designed, built and licensed transmissions for various applications including light and heavy road vehicles, military, marine, and rail vehicles as well as motor racing cars.

Following the death of Walter Wilson in 1957, his son A.Gordon Wilson took over the running of the company until his retirement in 1965.

The original company Improved Gears Ltd was incorporated on 28 December 1928, and this later became Self-Changing Gears. The company moved a number of times in the early years, and in 1938 settled in premises at Lythalls Lane, Coventry. During the war, additional premises were used at Burbage, Leicestershire.

In 1935, J D Siddeley sold his interests in Armstrong-Siddeley motors (including Self-Changing Gears) to Hawker Aircraft forming Hawker-Siddeley. In 1951 Leyland Motors Ltd bought into the company, resulting in each party owning one-third of the company, and in 1957 Leyland bought-out Hawker-Siddeley's shares in the company, thereby gaining control.

Many of British Railways' first generation diesel multiple units and shunting locomotives had gearboxes made by Self-Changing Gears. Examples include British Rail Class 100, 03 and 04; some of these are still in use on heritage railways.

The name Self-Changing Gears is sometimes confusing: the gearboxes are not fully automatic, selection of gear ratio remains a manual choice, but the gear-changing and any clutch control needed is automated. The gearboxes were used in conjunction with a fluid coupling so no clutch pedal was needed.

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