New Fully Automatic HydroMechanical Transmission A FULLY automatic transmission ti
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system employing a torque converter in conjunction with planetary gearing, is a feature of a Bussing underfloor-engined lorry on show at Geneva. Its advantages are that the high efficiency of the mechanical gearing is used predominantly, whilst the smooth operation and automatic adaptation to the load are fully maintained in the low-speed range. It has been designed to handle inputs of up to 200 b.h.p.
The arrangement of the system is simple as will be appreciated from the accompanying drawing. The drive from the engine goes to the planet gearcarrier (1) of the distributor (2). The planet pinions divide the power between two sun gears 3 and 4, gear 3 transmitting its torque to the pump impeller (5) of the torque converter (6) through hollow shaft 7.
Turbine runner 8 acts on the output shaft (9) through a free-wheel device (10) in the hydraulic circuit. Sun gear 4 is directly attached to the output shaft (9) to which it transmits its torque without any change, as it is in the mechanical circuit.
Engine Speed Halved When the vehicle is started, gear 4 is stationary and the convertor is driven at double the engine speed. As the convertor input is largely dependent upon the number of revolutions, engine speed is about halved, despite the throttle being wide open.
As the output-shaft (11) speed rises the transmission ratio towards the convertor decreases and, as a result, load is taken off the engine. At the same time, the mechanical energy being transmitted is being gradually increased, thus improving the overall efficiency.
At a predetermined speed, the convertor is automatically stopped as a result of the application of brake 12, the power transmitted thereafter being exclusively mechanical.
The engine can be started by towing the vehicle, and it can be used as a brake.
B8
The gear unit, known as the Diwabus is made by J. M. Voith, G.m.b.H., Herdenheim (Brenz), Germany. It will not be available until the summer of next year.
CAMPAIGN FOR Is. TAX CUT
STRIKING posters have been prepared by the Motor Agents' Association as part of their campaign for a reduction in fuel tax from 2s. 6d. to Is. 6d. per gallon. Some 34,000 are being distributed to 16,629 garages throughout the country.