EN
Powers of energy losses in a variable capacity displacement pump are compared with or without taking into account the power of hydraulic oil compression. Evaluation of power of liquid compression in the pump was made possible by the use of method, proposed by the Author, of determining the degree of liquid aeration in the pump . In the method of determining the liquid aeration in the pump and of powers of volumetric losses of liquid compression a simplified formula (qPvc × ∆pPi)/2 was used describing the field of indicated work of volumetric losses qPvc of liquid compression during one shaft revolution at indicated increase ∆pPi of pressure in the chambers. Three methods were used for comparing the sum of powers of volumetric losses ∆PPvl due to leakage and ∆PPvc of compression and also of mechanical losses resulting from increase ∆pPi of indicated pressure in the working chambers