Abstract: A sealing for back and forth moving machine elements, particularly for the sealing of rods for hydraulic cylinders, with a seal which seals against the housing as well as against the axially back and forth moving machine part, a preceding protection element which is arranged between the seal and the pressurized chamber of the cylinder, and a stripper, which stripper is turned toward the atmosphere. The preceding protection element is provided with a lip, the lip being directed toward the oil pressurized chamber, which lip touches the back and forth moving piston rod and has openings, which openings produce a connection between the pressurized oil chamber and that oil chamber which is formed between the preceding protection element and the lip seal.

Abstract: Rotary connection having a housing which is provided with annular ducts and with feed bores for pressurized oil and non-pressurized oil and having a piston-shaped inner part arranged in the housing, the inner part being formed with bores and with grooves on its periphery, for the passage of high-pressure oil and practically non-pressurized hydraulic oil. By means of a valve piston which can be acted-on at both end surfaces thereof with pressurized oil, lubricating ducts are connected, depending upon the switched position of the valve piston, via a central longitudinal bore provided with transverse bores, with the respective annular duct which at the time is not applied with pressurized oil.

Abstract: A valve piston for a hydraulic control valve in which the valve piston has piston sections thereon in axially spaced relation interconnected by a reduced diameter portion with at least one piston section having passage means formed on at least one end in diametrally opposite positions and taking the form of a notch formed into the end of the piston and having a concave axially bottom region with a flow body mounted in the notch and defining therewith an arcuate recess forming one end of the passage means and opening radially and axially outwardly near the periphery of the piston section while the other end of the passage means opens axially from the piston at a radially inner region thereof. The flow body and the notch define the passage means and which terminates at the periphery of the piston in a throttling region that directs fluid along an outwardly inclined path toward the respective end of the piston section.