Recent Developments in Automobile Transmissions

The paper is limited to the gearbox and to devices replacing the gearbox. The varied requirements of the transmission for different types of service and how far automatic gearchanging is desirable are discussed, and the author investigates the gain to be expected from infinitely variable transmissions. The increased popularity of synchromesh and the description of, and the present trend in current types of layshaft gearboxes, and current types of epicyclic gearboxes with the development of cone clutches instead of band brakes for epicyclic unit control are next dealt with. Under the heading of unorthodox gearboxes the German Z.F. layshaft box with electromagnetically operated clutches for synchronizing and engaging is discussed, as is also the synchro-self-shifting (S.S.S.) gearbox with traction clutch maintaining tractive effort during a change. Hydraulic transmission (including recent developments in fluid couplings), the present position of torque converters in road vehicle practice, and the possibilities of the combination torque converter and fluid coupling follow; finally, an attempt is made to forecast the future trend.