Abstract: A central body connects a driving motor and a pump driven by the driving motor through a shaft and a coupling. The hollow central body surrounds the coupling, connected on one side to the driving motor and connected on the other side to the pump. A fan is arranged in the central body and is connected with an inlet and an outlet. The central body has a heat exchanger through which the outlet from the fan is conducted. To further develop and improve this apparatus, a pressure medium tank is mounted in the central body and surrounds the driving shaft at some distance. The pump is connected with the pressure medium tank through its suction connector. The inlet to the fan is provided on the side of the driving motor.

Abstract: A compact hydraulic pumping and switching apparatus capable of pumping a hydraulic liquid in connection with an operating liquid supply tank, a clean liquid tank and a dirty liquid reservoir tank in three different modes. One mode fills the supply tank and filters the liquid. A second merely filters liquid from the supply tank. And the third drains the supply tank without filtering the liquid. The apparatus comprises a carrier coupling together, into a single unit, a motor, a pump, a filter and a switching device. The switching device has two spherical stop cocks therein, each with a passage comprising two perpendicular portions. The switching device is connected to the supply tank at two connections and to the clean liquid tank and to the dirty liquid reservoir tank at one connection respectively.

Abstract: A compact apparatus for filtering a liquid, such as hydraulic oil, including a filter housing having an inlet and an outlet, a filter element located therein, a rotary pump adjacent the filter housing and a separating element located inside the filter housing for separating the suction side and the pressure side of the pump. The filter element and the rotary pump are coaxially aligned and closely adjacent.

Abstract: A portable apparatus for filtering a liquid including a replaceable filter and a pump. A unitary connecting piece in the apparatus has a series of channels in the form of bores for connecting a suction inlet with the suction side of the pump, for connecting the pressure side of the pump with the filter housing and for connecting the filter element with a pressure outlet.