What do these air brake terms mean and what do they do to trains when they are applied or released?

Question

Run/Release, Service, Lap. What does it do to the trains braking system when these options are applied or released?
Which provides a quicker response to the brakes?

Answer 1

These terms can vary depending on the brake manufacturer and the country you're in. The likely meanings are:

Run/Release: The train/brake pipe which runs the length of the train is charged with air, releasing the brake.
Service: Holds the train/brake pipe at a certain pressure. This could be after the driver has made a brake application.
Lap: Vents air from the train/brake pipe which applies the brake. The driver would move his controller back to Service to stop venting. The more air that is vented, the more the brakes are applied.

There is also likely to be an emergency position which 'dumps' all the air rapidly from the train/brake pipe which applies the brakes very quickly.

Answer 2

Just click on HOGHEAD, go to my 360 blog and start with Hoghead's Highball No. 1 thru 10. All you need to know about train air-brakes is found there.

An advanced question, by the by. Well done.

Addendum: The 26L brake schedule is delved into in these posts. They are self-lapping. The "Lap" position is found on 24RL and 24M brake schedules. Not a lot of these critters left these days so I haven't gone into them. I will on the next Highball. Thanks for the idea.

Answer 3

Its worth reading up on dynamic brakes as well if you are interested in locomotive operation.