AIRCRAFT LANDING GEAR RETRACTION JACK IMPULSE FATIGUE TEST USING PARALLEL SERVO VALVE METHOD

摘要

Abstract This invention is used for generating a pressure rise of 200000 to 300000 psi/sec in accordance with MIL Standard MIL-S- 8812D. A single servo valve cannot provide the required flow to generate this pressure rise. Therefore, two or more servo valves are operated in parallel to achieve this rate. A single PID controller controls all the servo valves. A 20 Ipm, 450 bar hydraulic power source is used for demonstrating the specified rate of pressure rise. For achieving the rate of rise of pressure rise two servo valves, controlled by a PIC controller, are connected in parallel. The required input pressure profile is fed to the controller. The controller controls the servo valves to achieve required pressure profile at retraction jacks annular and full area ports. The hydraulic pump is driven at constant pressure and flow. Servo vales share the flow equally. The controller maintains the cycle count and stop at required cycles completion. If the volume of the retraction jack is high, more number of servo valves can be connected in parallel to achieve pressure rise.