Pressure medium operated vehicle gearbox - has servo-valves connected to control cylinders and control valves via relief valves

摘要

A pressure medium operated preselection and shift unit for a vehicle transmission has control valves associated with the control cylinders. The valves are switchable in relation to the control position of the cylinders. Servovalves are subjected to supply pressure and are connected to the control cylinders and control valves via relief valves which on operation of a coupling valve are switched by the supply pressure. The control system has the advantage that while maintaining a short switching time the engaging of a gear in the individual transmission groups is only permitted when the switching of the preceding group into the preselected shift position has been accomplished.