A complex pneumatic valve mounted on every freight car that responds to pressure changes in the main brake pipe. It performs three essential functions: charging the auxiliary reservoir from the brake pipe, applying the brakes by directing reservoir air to the brake cylinder when pipe pressure drops, and releasing the brakes by venting the cylinder when pipe pressure is restored.
We've a kicker in the consist, probably a sticky triple valve on one of those empty hoppers causing an emergency application.
Also heard as
- control valve
Related terms
Brake pipe
The air line running the full length of a train that charges and controls every car's brakes.
Big hole
The emergency position of the automatic brake valve, which vents the brake pipe and stops the train as fast as possible.
Kicker
A car whose brake valve throws the whole train into emergency when only a normal service application was made.