Electropneumatic control system for compressed air brakes of rail cars

Electropneumatic control system for the pressure in a main air pipe (37) of compressed air brakes of rail cars, with one inlet solenoid valve and one outlet solenoid valve (3 and 4) both constituted as a 3/2-way valve with a secondary valve part (13 or 14) that is connected non-parallel to a respective tight shutoff valve part (9 or 10) and acts at least as a restrictor in the closed state, said inlet and outlet solenoid valves having said tight shutoff valve parts (9 and 10) arranged in pneumatic connections from a main reservoir pipe (34) to a control chamber (26) and from said control chamber (26) to atmosphere via a brake nozzle (38'), said control chamber (26) being attached to said main air pipe (37) via a connection comprising a passage monitoring element (11, 12), whereby, when said inlet solenoid valve and said outlet solenoid valve are closed, said control chamber and a main air pipe chamber are under the same pressure, and with a relay valve (19) having a piston (20) pressurized by pressure in said control chamber (26) against pressure in said main air pipe (37), in order to actuate a two-way valve (21) comprising an inlet valve (22) and outlet valve (23), said inlet valve (22), open in said control chamber (26) only under prevalent pressure, being arranged in a connection from said main reservoir pipe (34) to said main air pipe (37);

• and the outlet valve (23), open in said main air pipe (37) only under prevalent pressure, being arranged in a connection from said main air pipe (37) to atmosphere, said secondary valve parts (13 and 14) being connected in series between said control chamber (26) and said main air pipe (37), so that these remain unaffected by the volumes in the main air pipe during pressure control processes in the control chamber (26).