Abstract: A ventilation device for a hydraulic cylinder providing a housing having a fluid passageway with an inlet and an outlet, and a closure member disposed in said passageway displaceable in obstructing relation with such inlet upon application of a first fluid force in such inlet, obstructing relation with such outlet upon application of a second fluid force on such inlet and in nonobstructing relation with either of such inlet and outlet upon application of a third fluid force between such first and second fluid forces.

Abstract: A twin-clutch for a twin-clutch variable speed transmission in motor vehicles includes two wet running multi-disk-clutches which are arranged axially in succession in a transmission housing, wherein end walls of the transmission housing are provided on respective sides of the multi disk clutches, a driving clutch housing; two transmission hubs outputting to transmission input shafts, and alternately drivingly connectable with the clutch housing via clutch disks; ring pistons shiftably supported in the end walls of the transmission housing and hydraulically pressurizeable with pressure oil via ducts arranged in the end walls to thereby cause a shifting of the ring pistons, wherein the ring pistons alternately act on the clutch disks via pressure disks, and wherein the pressure disks are actuatable from outside the clutch housing by the ring pistons; and axial rolling bearings respectively arranged between the ring pistons and the pressure disks.

Abstract: A twin-clutch for a twin-clutch variable speed transmission in motor vehicles includes two wet running multi-disk-clutches which are arranged axially in succession in a transmission housing, wherein end walls of the transmission housing are provided on respective sides of the multi disk clutches, a driving clutch housing; two transmission hubs outputting to transmission input shafts, and alternately drivingly connectable with the clutch housing via clutch disks; ring pistons shiftably supported in the end walls of the transmission housing and hydraulically pressurizeable with pressure oil via ducts arranged in the end walls to thereby cause a shifting of the ring pistons, wherein the ring pistons alternately act on the clutch disks via pressure disks, and wherein the pressure disks are actuatable from outside the clutch housing by the ring pistons; and axial rolling bearings respectively arranged between the ring pistons and the pressure disks.