Abstract: The invention relates to a filter device (10) for filtering a liquid, in particular a hydraulic oil, having a substantially cylindrical filter housing (12), which accommodates a filter element (30) and can be closed off by means of a cover (18), the filter element (30) having an associated untreated region (70) with an inlet (22) for supplying liquid which is to be filtered and a clean region (74) with an outlet (26) for removing filtered liquid, and the filter element (30) comprising an end plate (58) which is remote from the cover (18) and on which there is mounted a radially acting sealing element (62) for sealing the untreated region (70) of the filter element (30).

Abstract: In order to further develop a filter element, in particular for the filtration of mineral oils in hydraulic systems, having a filter material and a support tube which supports the filter material and is formed from a perforated plate with a multiplicity of flow openings, in such a manner that it is highly mechanically stable and can be produced at low cost, it is proposed, according to the invention, that the support tube has a joint which extends helically along the support-tube wall and is formed by those edges of the perforated plate which are in contact with one another in the circumferential direction.

Abstract: In a bypass filter unit, in particular, for filtering supplies of hydraulic oil in a bypass flow, comprising a motor-driven pump and a fixedly mounted filter housing closeable by a cover and containing an exchangeable filter element, it is proposed that the drive of the pump, the pump and the filter housing be arranged coaxially with one another, with the end of the filter housing that is closeable by the cover pointing upwards, that the filter housing be directly connected to the pump, and that the filter housing form a receptacle for the clean oil while the filter element is being changed, so as to enable changing of the filter element and renewal of the filter in a simple way and without risk of soiling the clean oil side.