SimHydraulics

Hydraulic Transmission with Secondary Control

This example shows the usage of the so-called "secondary control" in hydrostatic transmissions with a variable-displacement motor. The system consists of a hydrostatic transmission built of a pressure-compensated variable-displacement pump and a variable-displacement motor; a winch simulated with the Wheel and Axle block; mechanical load which includes mass M, damper D, and gravity force Weight; an accumulator, and the Secondary Control Unit. This unit is essentially a servo-cylinder controlled by a proportional 4-way valve. The servo- cylinder drives the control member of a variable-displacement motor represented in the model with mass M, spring TS, and damper D. The model is designed as a closed-loop control system with an angular velocity feedback. Dynamic compensator PD is installed in the Secondary Control Unit to improve system stability.