| Author | Message | ||
| bill chisholm (Billybandman)
Registered Member Username: Billybandman Post Number: 153 Registered: 2-2001 Posted From: 198.236.64.25 Rating: N/A |
There is air leaking from the bottom of my brake treadle valve when the Park brake is applied. If I push up on the little black rubber washer on the bottom of the Treadle Valve I can stop the air leak. Has anyone had the same problem and howndid you fix it. The only thing that I can figure is that the Park brake valve might be faulty and leaking back into the treadle valve. (Message edited by billybandman on November 23, 2009) | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1745 Registered: 12-2000 Posted From: 76.68.134.24  Rating: N/A |
Good choice. Symptoms would indicate the park brake valve. Its exhaust port is plumbed to the service circuit, so a leak internal to the park valve will leak out the bottom of the treadle valve. Changing it out can easily be written off as preventive maintenance, if it doesn't cure the problem. Let us know! happy coaching! buswarrior | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 927 Registered: 8-2006 Posted From: 99.39.13.151 Rating: N/A |
Another suggestion would be a blown parking diaphragm, which would allow air into the service portion, which would then be exhausted thru the treadle valve in the release position? As BW says, "Let us know what you find," please. Block the bus up securely at the jacking points, then go under and take a service hose off of one can, then apply the parking brake and see if you get air out of the can, or the hose. Air out of the can means it is the culprit, air out of the hose means the other can is the culprit. G (Message edited by george_mc6 on November 23, 2009) | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1746 Registered: 12-2000 Posted From: 76.71.100.170 Rating: N/A |
The relay valve is between the treadle valve and the brake chamber. Often doesn't show on the conceptual diagram that MCI has for the DD3 function. That service line in the picture is a control line, in reference to the DD3 chamber. Leaks out the exhaust of the relay may indicate diaphragm leaks. Wouldn't be unusual to get leaks from both places, because our coaches are WORN OUT before we get them. Preventive maintenance of the busnut air brake system is a methodical replacement of all components, as you can afford. Not as glamorous as a china toilet... happy coaching! buswarrior |