The main causes resulting in poor speed smoothness of the HVD set under open-looped condition are the insufficient linearity of pressure control and the insufficient pressure stability of relief valve used for speed regulating purpose of the HVD set,and usually worked under condition of small flow rate and low oil pressure.

Study on smooth start device with hydraulic slip clutch in a mill;

Magnetic Coupler Transmission and Application in the High Fluid Pressure Facilities,;