Zf Friedrichshafen Ag

Florian Langenbacher

Rainer Novak

Tobias Pfleger

Hans-Joachim Martin

Tobias Schmidt

A pressure back-up valve () includes a release piston () movable between first and second stop positions and a closing body () movable to a closing position in which this separates first and second connection pressure chambers () when the release piston () is in a first stop position. The release piston () moves the closing body (), in the second stop position, into an opening position. The release piston () is pressurizable on a first pressure surface (A) from a first side via a third connection pressure chamber () and on a second pressure surface (A) from a second side via a second connection pressure chamber (). The closing body () is pressurized, in the closing position, from a first side via the second connection pressure chamber () on a first pressure surface (A) and from a second side via the first connection pressure chamber () on a second pressure surface (A) of the closing body ().

Pressure back-up valve

A multi-speed transmission with hydraulically actuated shift rods, wherein an actuating pressure (p_B) is applicable by a valve device () and shuttle valves (C toD) to piston chambers (A toB) of pistons (to), the actuating pressure being adjustable by valves (). The piston chambers (A toB) can be brought into operative connection with a low-pressure region () by the shuttle valves (C toD) and a prefilling valve () or by the shuttle valves (C toD), the valve device (), and the valves (). Each of the shuttle valves (C toD) has a spring assembly (E toF), by which the shuttle valves (C toD) are held below a pressure threshold of the actuating pressure (p_B) in an operating state that connects the piston chambers (A toB) to the low-pressure region () by the prefilling valve ().

Growing community of inventors

Kressbronn, Germany

Florian Langenbacher