ELEKTROHYDRAULISCHE GANGWECHSELEINRICHTUNG FUER LASTSCHALTBARE WECHSELGETRIEBE

An automotive transmission with three or four stages corresponding to as many forward speeds, established by the activation of respective hydraulic coupling elements via associated electrical valve-operating switches, includes an individual delay network in the energizing circuit of each valve-operating switch for modifying its response time in dependence on load and on the direction of shift. By this modification an upshift under load or a downshift under pull proceeds with substantially immediate activation of one coupling element upon deactivation of another coupling element, whereas under other circumstances (downshift under load or upshift under pull) an appreciable hiatus occurs between deactivation and activation to take advantage of the intervening speed change. Discrimination between load and pull depends on the accelerator position whereas upshifting and downshifting are distinguished either mechanically, with the aid of a manually operated lever, or electrically on the basis of the state of activation of a coupling element of an adjoining stage. The delay networks retard either the deactivation or the activation of the associated coupling elements, depending on whether the latter are of the slow-operating or the fast-operating type.