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Return line and Suction Boost Filter RKM


The filter housings are designed in accordance with international regulations. They consist of a filter head, filter bowl and a screw-on or bolt-on cover plate.

Standard equipment:

  • With bypass valve
  • With back-pressure valve
  • Without anti-cavitation valve


RKM return line & suction boost filters are ideally suited 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), if the return flow is greater than the flow required on the suction side under operating conditions.


The return flow of the operating hydraulics is supplied to the filter via one or several inlets “A” and is cleaned by the filter element (full flow return line filtration). 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). The risk of cavitation is significantly reduced. The excess flow is drained to the tank via port “T”. A bypass valve “V2” (standard = 2.5 bar) is fitted to relieve excessive back pressures in the element (important on cold starts when the viscosity is high). This valve arrangement ensures that only finely filtered oil is available to the suction port during operation (exception: RKM 350). With optional valve “V3”, oil can be drawn 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).

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HYDAC Australia

HYDAC New Zealand

AUSTRALIA 1300 449 322

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