Barmag Barmer Maschinenfabrik Ag

Hydrolux S.a.r.l.

Dynamics Systems S.a.

Schwelm, Hans

Hans Schwelm

Example pilot-control stage for a proportionally controlled high-pressure hydraulic valves are disclosed. An example pilot-control stage includes a housing of a hydraulic valve, the housing comprising a piston chamber, a guide piston disposed within the piston chamber to move in an axial direction along the piston chamber, the guide piston having an aperture and a tappet, a compensating piston extending into the aperture, where the compensating piston moves in an axial direction along the aperture to define a compensating chamber, a bore fluidly coupling the hydraulic valve to the compensating chamber, an electromagnetic coil at least partially surrounding the piston chamber, and high-pressure seals between the compensating piston and the control piston, and between the tappet and the housing, where the control piston acts as an electromagnetic armature and current applied to the coil moves the guide piston and the tappet, and where the high-pressure seals isolate the piston chamber from the high-pressure areas.

Pilot-control stage for a proportionally controlled high-pressure hydraulic valve

The control block consists of four seat valves arranged in pairs above one another and opposite one another in two planes parallel to the base surface of the control block, the valves located diagonally opposite one another being controllable in pairs via a pilot valve. The logical combination of the invididual elements makes it possible to construct a compact, space-saving and handy control unit with a sealing surface arranged according to the customary standard pattern.

Hydraulic control block

An adjustable throttle valve is controlled by a low pressure control pressure acting on a spring urged adjusting cylinder for positioning the end of a follow-up piston adjacent the end of a discharge channel extending the length of a throttle piston; power fluid flows from a source through a discharge opening between a housing and the throttle piston with the spring force, the control pressure, infeed pressure and discharge pressure acting in concert to maintain the end of the follow-up piston adjacent but slightly spaced from the end of the discharge channel for maintaining throttle piston equilibrium.

Adjustable throttle valve

A hydraulic flow control valve is disclosed which is adapted for use as a pressure reducing valve, a flow control valve, or as a pressure relief valve. The valve includes a choke piston slidably mounted in a cylindrical bore for movement between a closed position closing communication between inlet and outlet channels, and an open position permitting such communication. An adjustable control system is provided for biasing the piston toward one of either its closed or open positions, and includes a constant volume flow restriction valve for providing a constant volume hydraulic flow. Downstream of the constant volume flow valve, there is provided a first branch line leading to an adjustable transducer for maintaining a selected pressure in the line, and a second parallel branch line leading to the bore in the housing for biasing the piston. Thus a selected pressure may be maintained in the second line, and thus also upon the piston, by adjustment of the transducer.

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Kaarst, Germany

Hans Schwelm