What are the possible cause of hydraulic system overheating?

practicaly overheating in a hydraulic systems occures due to1- bad oil coolers if an oil cooler is inslalled in a system2- overloading the hydraulic system to the relief valve setting and opening it for a long time3- internal leakage in the working components which results in high friction forces and so heat is generated and this last one as Mr. M. Arif mentioned below

there are some factories causes overheating in hydraulic system such as

1. Input power looses convert to heat
2. Bad coolant system beacause of there are leakage in pipes and bad filteratio that causes brasive wear so heat increased
3. Viscosity of oil if it light or heavey riases of heat
4. air bubblis in side the system increases heating ang wearing
5. Low diameters of pipes couses shear that raised heating

Heating of hydraulic fluid in operation is caused by inefficiencies. Inefficiencies result in losses of input power, which are converted to heat. A hydraulic system’s heat load is equal to the total power lost (PL) through inefficiencies and can be expressed as: PLtotal = PLpump + PLvalves + PLplumbing + PLactuators If the total input power lost to heat is greater than the heat dissipated, the hydraulic system will eventually overheat. Installed cooling capacity typically ranges between25 and40 percent of input power, depending on the type of hydraulic system.

SEVERIL CASES OF OVER HEATING1 GAGE CALEBRATION  FALS2 CONTANIMANT HYD 3 ANY BLOCKEG  IN RETURN LINE4 HYD OIL  NOT USED WITH SPECI OIL COOLING SYS IS NOT WORKING  PROPER

 ALWAY USED PROPER GRADE OIL