Combined valve for trailer vehicles having a parking brake

The combivalve (1) has a housing (2) containing an emergency braking piston (3) acted on by a spring (20) and incorporating a spring-loaded double valve element (14), cooperating with an inlet valve seat (17) and an outlet valve seat (30), an operating device for the combination valve providing travel and parking functions for the trailer vehicle, a control rod (28) of the operating device sliding within the housing coaxial to the emergency braking piston for pressurizing and venting the combicylinder (25) of the trailer parking brake.