Abstract: In order for a filter element with a casing, having filter material, with an end wall which terminates the casing on an upper side and has a through-passage opening, and with a bypass valve for opening and closing the through-passage opening, the bypass valve having a valve housing which is made of plastics material and accommodates a valve body and a valve spring which loads the valve body in the direction of a valve seat, to be configured such that it can be assembled more easily and produced more cost-effectively, it is proposed that the valve housing comprises a valve guide, and that a separate supporting element is provided, it being possible, for assembly purposes, for the valve body and the valve spring to be introduced into the valve guide and then for the supporting element to be fixed on the valve guide.

Abstract: To simplify the venting of a hydraulic circuit comprising a supply of hydraulic fluid, which is made available to a hydraulic consuming device via a pump, and a return filter comprising a filter housing and a filter element for filtering the hydraulic fluid returning from the consuming device in a return line, it is suggested that the return line comprise prior to entering the return filter a first pressure-maintaining valve which allows the return of the hydraulic fluid to the return filter only when a predetermined first pressure value is exceeded, that the return line be connected upstream in relation to the first pressure-maintaining valve to a venting device leading to the atmosphere and to a bypass line which contains a second pressure-maintaining valve and opens into the supply, wherein the second pressure-maintaining valve opens only when a predetermined second pressure value is exceeded and allows the return of the hydraulic fluid past the return filter to the hydraulic fluid supply, wherein the seco

Abstract: A return filter for hydraulic fluids comprises a filter head attachable to a container for fluid, a filter pot arranged on one side of the filter head, a cover releasably arranged on the other side of the filter head, a filter element arranged so as to extend continuously through the filter head and the filter pot, at least one inlet formed on the filter head for the returning fluid, an air port formed on the filter head, and a ventilation filter inserted into this port. Filter head, filter pot and filter cover consist of plastic; a hose nipple integral with the filter head is formed at the inlet for the returning fluid. The air port is surrounded by a housing which is integral with the filter head and is closable by a cover carrying the ventilation filter. The walls of the housing are provided with slots which are open towards the cover. On the one hand, these slots make provision for air to pass through and, on the other hand, they allow the cover to be releasably clipped into the housing.

Abstract: A pipe extension for a filtering pot of a return filter has an outlet connection projecting from the filtering pot at its free end and a pipe secured to the outlet connection. An annular groove extending in circumferential direction is arranged at the outlet connection and an annular seal which does not protrude radially beyond the outer circumference of the outlet connection is inserted into the annular groove. Radially projecting, axially extending conical webs are provided at the outer circumference of the pipe connection in the region between the annular groove and the filtering pot and a pipe consisting of metal is pushed onto these webs, whereby the pushed-on pipe is expanded by the conically extending webs to achieve a secure seat. A bead reaching into the annular groove is introduced into the pushed-on pipe.