A continuous air line made of piping under each car, joined by hoses between cars and charged from the locomotive to about 90 psi on most freight trains and 110 psi on passenger trains. Each car's control valve reads the brake pipe: a drop in pressure applies the brakes and a rise releases them. Leaks, a kinked hose or a closed angle cock all show up as brake pipe trouble, so the engineer watches its gauge and the rear-end reading constantly.
Rear's only showing 68 on the brake pipe, so we've got a leak somewhere. Walk it back and listen for it.
Old heads call it the train line, and charging the train line means pumping the brake pipe back up after coupling.
Also heard as
- train line
- trainline
- the air
Related terms
Set and release
Applying the train's air brakes and then releasing them, the basic sequence of every air brake test.
Big hole
The emergency position of the automatic brake valve, which vents the brake pipe and stops the train as fast as possible.
Glad hands
The coupling heads on the ends of air brake hoses, which lock together when two cars are joined.
EOT
End-of-train device: a unit hung on the last car's coupler that reports rear brake pipe pressure and motion to the head end.
Lace up the air
To connect the air hoses between cars and open the angle cocks so the brake pipe runs through.