HYDRAULIC TRANSMISSION COMPRISING VARIABLE DISPLACEMENT PUMP OR MOTOR OPERABLE WITH DISCONTINUOUS RANGE OF DISPLACEMENTS

摘要

A hydraulic transmission comprises a variable displacement hydraulic pump and a variable displacement hydraulic motor, connected by high and low pressure lines. One of the hydraulic pump and the hydraulic motor has a discontinuous range of displacements. The other has a continuous range of displacements. In order to allow a continuous range of input and output torques, despite the discontinuous range of displacements, the pressure in a high pressure line is varied. This enables a hydraulic pump or motor which has a discontinuous range of displacements but other technical advantages, such as reduced torque ripple, to be employed without losing fine control of input and output torque. The hydraulic transmission is useful for a wind turbine where the turbine drives a hydraulic pump operated with a discontinuous range of displacements.