Working liquid compressibility may considerably change the values and proportions ofcoefficients of the volumetric and mechanical energy losses in the displacement pump usedin a hydrostatic drive system. This effect can be particularly seen in the operation underhigh pressure and also in the system, where aeration of the working liquid can occur. Inthe Part II the mathematical model is presented of the torque of mechanical losses in thepump and its laboratory verification. Conclusions are drawn regarding the effect of workingliquid compressibility on the mechanical and volumetric losses in the pump.
