DE2457301

• Main Authors: AUDIFFRED JUN., SIDNEY JOSEPH, WASHINGTON, ILL., US, MATHES, HAROLD ARTHUR, TREMONT, ILL., US
• Format: Patent
• Language: English
• Published: 23.10.1986
• Edition: 4
• Subjects: BLASTING; BRAKES; CLUTCHES; COUPLINGS FOR TRANSMITTING ROTATION; ENGINEERING ELEMENTS AND UNITS; GEARING; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVEFUNCTIONING OF MACHINES OR INSTALLATIONS; HEATING; LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS; LIGHTING; MECHANICAL ENGINEERING; MOTOR VEHICLES; PERFORMING OPERATIONS; THERMAL INSULATION IN GENERAL; TRAILERS; TRANSPORTING; WEAPONS

A hydraulic system responsive to movement of a shift lever actuates predetermined pairs of drive establishing devices in a vehicle transmission by applying a gradual fluid pressure rise to one such device to provide a selected drive ratio and by applying a delayed lesser gradual pressure rise to the other device of the pair to determine drive direction and to reestablish power flow through the transmission. The circuit also blocks fluid pressure from at least one of the pair of devices if the vehicle engine is started up with the control lever at a position other than neutral and neutralizes the transmission when the vehicle brakes are applied but maintains full fluid pressure at other vehicle components, such as the brakes, under both conditions. These functions including resetting at the beginning of each shift are all accomplished within a pair of selector valves, a pressure modulation valve assembly and a single spool safety differential valve in a compact, simplified and economically manufactured arrangement having a reduced number of separate components.