Device used to add heat to the hydraulic fluid. It is required where the temperature of the fluid should also be constant at the start of the operating period. The preheating normally takes place electrically using heating cartridges with a low specific heat performance (max. 2 W/cm2 for heating rods and 0.5 W/cm2 for heating cartridges) or hydraulically using throttle valves.
Fluidlexikon