FIELD: transport engineering; pneumatic brake systems. SUBSTANCE: throttle valve with variable cross section is installed in trailer supply line from prime mover. In case of breakage of trailer supply line connecting brake systems of prime mover and trailer, compressed air stream from trailer compressed air source to trailer system is throttled to provide forced braking of trailer. Throttle valve has first actuating member which provides operation of throttle valve and second actuating member which serves as throttling piston for throttling compressed air stream. EFFECT: improved reliability of braking. 16 cl, 4 dwg
