In this article, two hydrostatic systems with a throttling steering fed by a constant capacity pump were compared. It also includes a subject matter connected with an energy loss power of hydrostatic systems with hydraulic cylinder controlled by proportional directional control valve. Diagrams of loss power of two hydraulic systems worked at the same parameters of a speed and a load of hydraulic cylinder, which were different due to structure and ability of an energy saving, were presented and were compared. There are possibilities to reduce energy losses in proportional control systems (in the pump, in the throttle control unit, especially in the cylinder), and thus to improve the energy efficiency of the throttling manifold. The considerations allow for comparison of the loss power resulting from the applied hydraulic control structure of the hydraulic cylinder and the power consumed by the pump from the electric motor that drives it, the power necessary to provide the required unchanged usable pump-driven hydraulic cylinder. Presents the impact on the output (useful) power of the power consumed in the considered systems, and the impact on the power consumed of the loss power in the individual elements. Instantaneous useful power of the cylinder, which is determined by the product of force and speed of the cylinder rod, is independent of all losses. There are mechanical loss power occurs in the cylinder, the loss power in the conduits, the structural volume and pressure loss power that are associated with the throttling control and loss power in the pump: pressure, volumetric and mechanical which have to be added to the useful power. As a result, the sum of the effective useful power and the loss power of all system is the instantaneous value of the power consumed by the pump from the electric motor that drives it.