page_title: Preselector gearbox
section_title: Cotal
hierarchical_section_title: Preselector gearbox / Designs / Other epicyclic designs / Cotal
caption_attribution_description: English: Dashboard of a 1954 Salmson 2300 Coupé, the only one in the United States. 88 remain worldwide, nearly all of them located in France. RHD, as was common for continental luxury cars of the interwar and immediate postwar eras. Cotal electromagnetically operated ZF transmission.
context_page_description: 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 is that the gear shift lever allowed the driver to "pre-select" the next gear, usually with the transmission remaining in the current gear until the driver pressed the "gear change pedal" at the desired time.
  The design removed the need for the driver to master the timing of using a clutch pedal and shift lever in order to achieve a smooth shift in a non-synchromesh manual transmission. Most pre-selector transmissions avoid a driver-controlled clutch entirely. Some use one solely for starting from a standstill. Preselector gearboxes were most common prior to the widespread adoption of the automatic transmission, so they were considered in comparison to the "crash gearbox" type of manual transmission.
  Preselector gearboxes were often marketed as "self-changing" gearboxes, however this is an inaccurate description as the driver is required to choose the gear.
context_section_description: During the 1920s and 1930s, several French luxury car manufacturers used three-speed or four-speed preselector gearbox manufactured by Cotal. A unique aspect of the Cotal gearbox was the use of electromagnetic clutches (instead of band brakes) to engage the gears. A downside to this approach was that a loss of electrical power meant that the engine could no longer drive the wheels. The clutches were controlled by a simple dashboard or column-mounted switch, described as "a cherry on a cocktail stick", and relays. There was no mechanical servo action, so no need for the Wilson's cam or toggle arrangements and the change gear pedal.
caption: 1954 Salmson 2300S; gear selection lever mounted on the left side of the steering column
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