Control system for variable displacement motors

摘要

A hydraulic motor control system comprises a speed control loop (76,92,62,68) and a pressure control loop (74,92,58) which provide closed loop control of a variable displacement chamber space and the mechanical advantage coupling thereof to the motor output shaft. The speed control loop is effective in the speed control mode of operation to maintain a set speed within a given load range. In response to load increases beyond said range, the pressure control loop pre- empts the speed control loop so that the control operates to maintain a predetermined load.