Flow Saturated Step Response of a Hydraulic Servo

This paper reports a theoretical and experimental investigation of the displacement and pressure responses of a closed loop hydraulic servo to a very large step input. The latter ensures that the servovalve ports are fully open and the servo flow-saturated for substantial periods. The nonlinear equations are solved by both analogue and digital computation with analytical solutions in particular situations. Approximations for the displacement response and the maximum pressure attained are evaluated and shown to be acceptable. Experimental values compare reasonably well with predictions An important conclusion is that such a servo cannot cavitate during a step response