New Small Automatic Transmission Introduced
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A NNOUNCED today is a new Borg.C1 Warner fully automatic transmission developed for use with 14-litre engines. The new unit will be exhibited by BorgWarner, Ltd., at the forthcoming London Motor Show, which opens on October 18.
The transmission is known as the model 35 and consists of two main components: a hydraulic torque converter and a hydraulically operated automatic gearbox. The torque converter multiplies the .gear ratios at an infinitely variable rate between 2 to 1 and 1 to 3, and is available in different diameters to match the torque characteristics of various engines.
The gearbox section incorporates an epicyclic gear set providing three forward ratios-2.39, 1.45 and 1 to 1—and a reverse ratio of 2.09 to I. These ratios are obtained by engaging hydraulically operated multi-disc clutches and brake bands, and the torque converter and gearbox section share a common fluid supply.
Control of the gearbox is given by a selector which, in addition to the normal automatic drive position provides park. reverse, neutral and lock-up. The starting control is operative only in park and neutral. With lock-up in use the vehicle remains in first gear, and if this position is selected at speeds up to 20 m.p.h. an immediate change-down to first gear occurs: at speeds above 20 m.p.h. second is engaged. Down changes from third to second or first occur in the normal way automatically with decreasing vehicle speed, but to obtain maximum acceleration full depression of the accelerator pedal produces a " kick-down " effect. Top gear can, however, be held at vehicle speed down to about 10 m.p.h.
Details of the size and weight of the Borg-Warner model 35 transmission have not been released yet, but the makers claim that the weight penalty often associated with automatic transmission has been wholly eliminated by the extensive use of light alloys.