Doc. dr. Franc Majdič, Univerza v Ljubljani, Fakulteta za strojništvo
Dr. Jožef Pezdirnik, Uredništvo revije Ventil, UL, FS

Abstract:
Internal leakage occurs in a lot of hydraulic components; pumps, hydromotors, spool sliding valves. Inside of them a gap exists between the two elements with relative velocities. At pressure differences a certain flow, named internal leakage, leaks through this gap. Internal leakage is unavoidable for the components functioning with elements with sliding contacts. During years of application because of the wear of sliding surfaces the internal leakage increases. The higher contamination of the liquid the more intensive wear is, what means increasing of internal leakage. The consequence results in reducing volumetric efficiency of the components and the system, following the reduction of working velocity of the machine.

Keywords:
power-control hydraulics, hydraulic components, liquids, internal leakage, gap between sliding elements, contamination particles