Self-Changing Gears
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Self-Changing Gears was a British company, set up and owned equally by
Walter Gordon Wilson Major Walter Gordon Wilson (21 April 1874 – 1 July 1957) was an Irish mechanical engineer, inventor and member of the British Royal Naval Air Service. He was credited by the 1919 Royal Commission on Awards to Inventors as the co-inventor of the ...
and
John Davenport Siddeley John Davenport Siddeley, 1st Baron Kenilworth (5 August 1866 – 3 November 1953), was a pioneer of the motor industry in the United Kingdom, manufacturing aero engines and airframes as well as motor vehicles. Career The eldest son of William ...
, to develop and exploit the Wilson or
pre-selector gearbox A preselector gearbox is a type of manual transmission mostly used on passenger cars and racing cars in the 1930s, in buses from 1940-1960 and in armoured vehicles from the 1930s to the 1970s. The defining characteristic of a preselector 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.


Ownership changes

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 (SCG). The company moved a number of times in the early years, and in 1938 settled in premises at Lythalls Lane,
Coventry Coventry ( or ) is a City status in the United Kingdom, city in the West Midlands (county), West Midlands, England. It is on the River Sherbourne. Coventry has been a large settlement for centuries, although it was not founded and given its ...
. During
World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...
, additional premises were used at
Burbage, Leicestershire Burbage is a large village in the Borough of Hinckley and Bosworth in Leicestershire, England.OS Explorer Map 232 : Nuneaton & Tamworth: (1:25 000) : According to the United Kingdom Census 2001 the parish had a population of 14,324, increasin ...
. In 1935, Siddeley sold his interests in
Armstrong Siddeley Armstrong Siddeley was a British engineering group that operated during the first half of the 20th century. It was formed in 1919 and is best known for the production of luxury vehicles and aircraft engines. The company was created following ...
(including Self-Changing Gears) to
Hawker Aircraft Hawker Aircraft Limited was a British aircraft manufacturer that was responsible for some of the most famous products in British aviation history. History Hawker had its roots in the aftermath of the First World War, which resulted in the bank ...
forming
Hawker Siddeley Hawker Siddeley was a group of British manufacturing companies engaged in aircraft production. Hawker Siddeley combined the legacies of several British aircraft manufacturers, emerging through a series of mergers and acquisitions as one of onl ...
. In 1951
Leyland Motors Leyland Motors Limited (later known as the Leyland Motor Corporation) was a British vehicle manufacturer of lorries, buses and trolleybuses. The company diversified into car manufacturing with its acquisitions of Triumph and Rover in 1960 and 1 ...
bought into the company, resulting in each party owning one-third of the company, and in 1957 Leyland bought-out Hawker-Siddeley's shares, thereby gaining control. In 1986 the business was sold to
Cummins Cummins Inc. is an American multinational corporation that designs, manufactures, and distributes engines, filtration, and power generation products. Cummins also services engines and related equipment, including fuel systems, controls, air ...
.


Railway applications

Many of
British Rail British Railways (BR), which from 1965 traded as British Rail, was a state-owned company that operated most of the overground rail transport in Great Britain from 1948 to 1997. It was formed from the nationalisation of the Big Four British rai ...
ways' first generation
diesel multiple unit A diesel multiple unit or DMU is a multiple-unit train powered by on-board diesel engines. A DMU requires no separate locomotive, as the engines are incorporated into one or more of the carriages. Diesel-powered single-unit railcars are also ...
s and shunting locomotives had gearboxes made by Self-Changing Gears. Examples include
British Rail Class 100 The British Rail Class 100 diesel multiple units were built by Gloucester Railway Carriage and Wagon Company Limited from 1956 to 1958, designed and built in collaboration with the Transport Sales Dept. of T.I. (Group Services) Ltd. Introducti ...
, 03 and 04; some of these are still in use on
heritage railways A heritage railway or heritage railroad (US usage) is a railway operated as living history to re-create or preserve railway scenes of the past. Heritage railways are often old railway lines preserved in a state depicting a period (or periods) i ...
. In the 1980s, SCG gearboxes were fitted to 141,
142 142 may refer to: * 142 (number), an integer * AD 142 Year 142 ( CXLII) was a common year starting on Sunday (link will display the full calendar) of the Julian calendar. At the time, it was known in the Roman Empire as the Year of the Consul ...
, 143,.
144 144 may refer to: * 144 (number), the natural number following 143 and preceding 145 * AD 144, a year of the Julian calendar, in the second century AD * 144 BC, a year of the pre-Julian Roman calendar * 144 (film), ''144'' (film), a 2015 Indian com ...
and
150 150 may refer to: *150 (number), a natural number *AD 150, a year in the 2nd century AD *150 BC, a year in the 2nd century BC *150 Regiment RLC *Combined Task Force 150 See also * List of highways numbered 150 The following highways are numbered ...
class DMUs. 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 A fluid coupling or hydraulic coupling is a hydrodynamic or 'hydrokinetic' device used to transmit rotating mechanical power.
so no
clutch A clutch is a mechanical device that engages and disengages power transmission, especially from a drive shaft to a driven shaft. In the simplest application, clutches connect and disconnect two rotating shafts (drive shafts or line shafts). ...
pedal was needed. Gearboxes installed in locomotives built by the
Vulcan Foundry The Vulcan Foundry Limited was an English locomotive builder sited at Newton-le-Willows, Lancashire (now Merseyside). History The Vulcan Foundry opened in 1832, as Charles Tayleur and Company to produce girders for bridges, switches, crossi ...
for the
Drewry Car Company The Drewry Car Co was a railway locomotive and railcar manufacturer and sales organisation from 1906 to 1984. At the start and the end of its life it built its own products, for the rest of the time it sold vehicles manufactured by sub-contract ...
were designated "Wilson-Drewry".http://www.enuii.com/vulcan_foundry/photographs/Pre%20EE%20Diesel/vulcan%20drewry%200-6-0%20diesel%20shunter.pdf


Bus applications

The bus manufacturing industry was a major customer of the company. Buses on city work need to start and stop every minute or less, and the effort required with a manual gearbox was substantial. In addition, for most of the period when these transmissions were dominant buses still had unassisted steering, and the overall effort needed without assistance was fatiguing. From about 1935 to 1960, buses by AEC, Daimler, and sometimes
Bristol Bristol () is a city, ceremonial county and unitary authority in England. Situated on the River Avon, it is bordered by the ceremonial counties of Gloucestershire to the north and Somerset to the south. Bristol is the most populous city in ...
, Guy and Leyland offered Preselector gearboxes, either as an option or as standard. London buses invariably used this transmission, along with other cities. Country area buses still commonly retained manual transmissions as they did not have the requirement of constant stopping and starting at bus stops. The London specification included compressed air operation of the change-gear pedal, where others used unassisted operation. Around 1960, the bus industry was changing from traditional vehicles with engine at the front and driver in a small separate cabin alongside, to entrance at the front alongside the driver, and the engine and gearbox remotely mounted under the floor or at the rear. SCG devised the
semi-automatic gearbox A semi-automatic transmission is a "theoretical" multiple-speed transmission where part of its operation is automated (typically the actuation of the clutch), but the driver's input would be required to launch the vehicle from a standstill and to ...
, under their brand name "Pneumocyclic" as an advance. It had the same gearbox principle, but instead of pre-selecting a gear and then separately operating a change-gear pedal, both functions were combined and operated from a small lever alongside the steering wheel, the driver merely moving this to the next gear and the transmission responding accordingly. The mechanism was operated either by air pressure or low-voltage electrics, although the physical gearshifting in the gearbox was nearly always by air pressure, (some vehicles used high pressure hydraulics, notably BMMO vehicles). This style of transmission was also widespread in UK buses, from a range of manufacturers, until different types came onto the market in the 1980s. A further advance was the fully automatic gearbox, which still used the same principles but shifted gears automatically. This was pioneered on the
AEC Routemaster The AEC Routemaster is a Front-engine, rear-wheel-drive layout, front-engined double-decker bus that was designed by London Transport Executive, London Transport and built by the Associated Equipment Company (AEC) and Park Royal Vehicles. The ...
, and later spread, although not widely, to other vehicle types.


References

* * {{Authority control Automotive transmission makers British Leyland Engineering companies of the United Kingdom