IMPROVEMENTS IN AND RELATING TO A POSITIVE DISPLACEMENT MACHINE WITH A CONTINUOUSLY VARIABLE ADJUSTMENT FOR A HYDROSTATIC GEAR

摘要

1288148 Hydrostatic transmissions J WUEZER 9 June 1970 [8 July 1969] 27776/70 Heading F2C [Also in Division F1] In a hydrostatic transmission, the displacement volume of the pump 1 and the motor 2 is controlled by accumulators 19 in the pump cylinder block 5 and accumulators 20 in the motor pistons 4 the pressure at the pump inlet and motor outlet being controlled to determine the proportion of the displacement absorbed by the accumulators. At a lower limit pressure in the pump inlet and motor outlet set by pressure regulator 25, accumulator pistons 19 are fully extended while traversing inlet chamber 29 and are fully retracted by the outlet pressure in chamber 30, thereby absorbing the whole output of the pump pistons 3, so that the motor remains stationary. At an upper limit pressure, pistons 19 are fully retracted while traversing both chamber 29 and chamber 30 so that maximum displacement is obtained, the motor accumulator pistons also being fully retracted so that the motor rotates at the same speed as the pump. Between the upper and lower limits, the speed ratio is infinitely variable by controller 25. The control lever 26 of the controller 25 also can be set for forward or reverse rotation of the transmission, and may be remote-controlled by an hydraulic telemotor 35. The controller 25 is arranged to automatically lower the pressure in the pump inlet and motor outlet when the pump outlet and motor inlet pressure rises to a predetermined level, to prevent overloading the power source, which may be a gas turbine, Fig. 2 (not shown), or an I.C. engine, Fig. 3 (not shown). The pump and motor casings have cooling fins 38, 39.