Having a problem with our Westinghouse 8 1/2 x120 air pump. Works fine pumping main to 110psi, then it moans slowly to try and maintain it rather than waiting for a 1-2psi drop in m/r pressure. I have cleaned the govoner, shuttle and reversing valves, checked the locomotive and there is no air leaks in the system to make it do this. The automatic oilers are working properly and the oil lines are clear and free. I have removed the air valves and they all seem to be in good shape and sealing good. Any ideas would be appreciated.

B.M.

Brian,

If the compressor does not come to a crisp stop when main res. pressure is reached, this means the governor is not shutting steam to the compressor. What type of governor do you have? Single or double head? What I like to do is pull the governor off and test it using shop air to the head with the lower body of the governor removed so you can see the valve stem move. See if its action is sluggish or if it moves not at all. Then I usually check the pin valve in the head. Sometimes the brass diaphrams will crack due to work hardening which will cause troubles. While the head is off the body, hook air to the opening and see if the piston works well and if there is any blow by. Finally, pull the piston and make sure the ring is not gummed into the ring groove. If any parts are worn out they can be easily made or purchased depending on your skill level, budget, and time frame. Usually it is a good idea to lap all the valve surfaces lightly while it is apart. Rebuilding a governor is not difficult, and I think this is probably where your problem lies.

Best,

Stathi Pappas