Zahnradfabrik Friedrichshafen, Ag.

Zf Friedrichshafen Ag

Alfons Loffler

Josef Schwarz

Walter Marte

Peter Wiggermann

Hydrodynamic converter with a bridging coupling

Hydraulic pressure-control device with parallel compression springs

A hydraulic control device for the pressurization of a clutch or the like for a transmission operable under load comprises a spool-type valve displaceable in one direction to pressurize the clutch and in the opposite direction to vent the same. The valve spool operates with a damping piston which receives the clutch pressure buildup and acts against a control piston which, in turn, is displaced by an operative valve. According to the invention, the pressure head is maintained substantially constant by providing a sleeve or bushing within the damping piston chamber which bears against the spool by a spring and which can be biased by a spring between the damping piston and the sleeve.

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Friedrichshafen, Germany

Alfons Loffler