Ensuring oil with finely filtration:
The supply of the return flow of the operating hydraulics to the filter happens via one or several inlets "A". The filter element (full flow return line filtration) cleans it. A pressure of 0.5 bar (standard) is applied inside the element by the back-pressure valve "V1". This ensures that the filtered return line flow is available to the hydrostatic feed pumps connected in "B" ports (full flow suction boost filtration). It significantly reduces the risk of cavitation. Also, it drains the excess flow to the tank via port "T". A fixation of a bypass valve "V2" (standard = 2.5 bar) occurs to relieve excessive back pressures in the element (important on cold starts when the viscosity is high). This valve arrangement ensures that only oil with finely filtration is available to the suction port during operation (exception: RKM 350).
With optional valve "V3", it's possible to drow oil from the tank for short periods, e.g. initial filling, venting after changing element.
The filter elements used in RKM filters are notable for low back-pressures, especially at high viscosities (e.g. cold starts).
The design of the filter housings is in accordance with international regulations. They consist of a filter head, filter bowl and a screw-on or bolt-on cover plate.
- With bypass valve
- With back-pressure valve
- Without anti-cavitation valve
RKM return line & suction boost filters are ideal for use in equipment with two or more circuits. In particular, this filter is the "first choice" for mobile machinery using hydrostatic drives (e.g. wheel loaders, forklift trucks, harvesting machines). Especially if the return flow is greater than the flow required on the suction side under operating conditions.