Characteristics of Multiple Range Hydromechanical Transmissions

The purpose of this paper is to show the advantages of multirange hydromechanical transmissions and to show some basic relationships of primary design parameters. Hydromechanical transmissions can be designed so that they maintain a high efficiency over a wide range of torque/speed variations. The amount of volumetric loss and, therefore, slip, can be reduced to a minimum; therefore, it is possible to control the speed of the powerplant by proper ratio control.

The powerplant and transmission can be considered as one system which is permitted to operate, under optimum conditions, irrespective of the road load or speed of the vehicle.