A Method to Avoid the Stick-Slip in a Large Hydraulic Cylinder under Variable Load using a balanced Valve

Stick-slip motion often appears for starting or at low speed of hydraulic cylinder. In this paper, a method to avoid stick-slip is proposed by using a balance valve in the outlet which develops the back pressure. The performance of the proposed system to avoid stick-slip motion is simulated by using AMESim software and compared with the conventional system which has a hydraulic lock in the outlet. The results confirmed that the critical velocity (Stribeck velocity), an important parameter of stick-slip, can be much higher than the conventional system. Also, orifice diameter of pilot spool must be smaller than the nominal value to reduce stick-slip motion when negative load applies on the hydraulic cylinder.