Re: Air valve

As previously discussed, it is a New York Air Brake valve.

If I remember right it is a model A-1 (Wabco/NYAB seemed to have dozens of model A-1s in every variety imaginable), but it is a caboose valve that would be found mounted in the cupola within reach of the crew. The normal position is "LAP" which closes the rotary valve connection to the exhaust. As the valve is moved it opens larger ports from the brake pipe to exhaust. The crew was only supposed to open enough to cause a retarding effect, which the engineer was supposed to acknowledge by whistle/radio and placing his brake valve in lap. In an emergency, the valve would be moved full travel to the APP position dumping the air. The second pipe connection should be marked BP for brake pipe.

When newer pressure maintaining brake valves came into use (1950s+ some 24RL and all 26+), this actually contributed to some accidents by the crew mishandling it and causing an undesired release. A newer version (A-2?) looked and worked similar, but required the crew to move the handle all the way to APP before it could be returned to LAP. An intermediate position could be used to bring the train to a controlled stop, but an emergency application had to be made before it could be reset.