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Hydrostatic Could Cut Running Costs
Page 104
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"AUTOMATIC transmission — the challenge of the heavy vehicle " was the subject. of a paper read by Dr. J. Cl Giles, consulting engineer and ex-deputy director of the Mot& Industry Research Association at a meeting of the Institute of Road Transport Engineers, Midland Centre, on Tuesday. After outlining established types of stepped gearboxes and hydrokinetic transmissions and their application, Dr. Giles mentioned a number of hydrostatic units, notably a twin-shunt split-torque transmission with which he is personally Concerned; this essentially comprises a slipper-vane pump and a slipper-vane motor.mounted on the same axis as an ePicyclic doubledifferential gear, and the units are connected in such a way that the transmission of power hydraulically is zero at 'a high and low point in the speed-ratio
range and varies between 28 per cent. and 45 per cent, in the intermediate part of the range. The hydrostatic units are required to operate at only moderate efficiency to achieve an overall transmission efficiency of around 90 per cent.
In a review of the benefits of automatic transmission Dr. Giles emphasized that power-maintained gear changes would be of great advantage to the goods-vehicle driver and should offer a reduced fuel bill. This would be achieved by operation of the engine continuously in the high-torque, high-efficiency part of its performance range. It would seem doubtful whether the hydrokinetic transmission could offer improved operating economy ',and' the further study and development of shunt-type hydrostatic units appeared to be the best approach
to the problem P.A.C.B.