Valve arrangement for the control system of a gearbox

摘要

A description is given of a valve arrangement for the control system of a gearbox, in particular a powershift gearbox, with a plurality of gear-shifting elements, such as for example gear-shift clutches, which can be activated selectively for changing various gears. To change the various gears the shifting members are assigned a central shift valve which has at least a number of shift positions which corresponds to the number of gears, in which positions, on the one hand, the supply pressure is imparted to at least one selected shifting member and, on the other hand, at least one further shifting member is relieved of load. Connected upstream of the central shift valve is a control valve, the starting pressure of which, which determines the position of the shift valve, can be adjusted by means of an adjusting device. This valve arrangement makes it possible to reduce the number of relatively costly magnets and, at the same time, to provide the prerequisite that the control valve, which is connected upstream, may be used in order to match the shift pressures to the load condition.