Brake system for vehicle combinations

Claim 1

A brake system for controlling brakes on a primary and a secondary vehicle in tandem in which: said primary vehicle includes at least three pneumatic pressure lines operatively connected in said brake system for operating and controlling brakes on said primary and said secondary vehicle; a foot operated braking signal transducer which includes means for controlling an electrical signal to an electronic switching device and means for controlling one of said pneumatic pressure lines; 2/2 way magnetic valves for electrically controlling pneumatic pressure from said one pneumatic pressure line to said brakes on said primary vehicle; electromagnetic blocking valves on said primary vehicle for blocking pneumatic pressure from said one pneumatic pressure line to said brakes on said primary vehicle during operation of said 2/2 way magnetic valves for applying pneumatic pressure to said brakes on said primary vehicle; an electronic switching device on said primary vehicle for processing different electrical signals and providing an output for controlling said 2/2 way magnetic valves and for producing a control signal for said secondary vehicle; a pneumatic control valve on said primary vehicle which is controlled by pneumatic pressure on said primary vehicle for controlling pneumatic pressure over first and second pneumatic pressure lines to said secondary vehicle; and said secondary vehicle includes pneumatic operated brake circuits which are connected to said first and second pneumatic pressure lines on said primary vehicle for pneumatic operation of brakes on said secondary vehicle and means for connecting an electrically operated brake circuit on said secondary vehicle to said control signal on said primary vehicle produced for said secondary vehicle.