| Author |
Message |
CHUCK STONE (208.180.95.13)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, January 09, 2003 - 11:53 am: | |
I have an MC7 that hasn't been driven in about two months, my parking brakes are stuck and the bus won't roll. How can I get the brakes to release? They periodically stick, but this is the first time the brakes have NOT released. Air pressure is excellent. |
Ace (24.28.44.126)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, January 09, 2003 - 5:15 pm: | |
Try holding the brake pedal down for about 10-15 seconds and release. The brakes should release at that time!
Ace |
Al (64.12.96.235)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, January 09, 2003 - 9:11 pm: | |
Set your parking brakes again. Bring bus up to full air presure, then apply a full brake application and hold it, then release parking brake while brake is apply. This should release the praking brake.
Hope this helps. AL |
RJ Long (24.127.74.29)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, January 09, 2003 - 10:55 pm: | |
Al & Chuck -
The MC-7 typically has DD3 rear brake chambers on the drive axle.
Al, you've got the release concept correct, you've just got the order reversed!
~ Set the parking brake
~ Build to full air pressure (Compressor "pops" off)
~ LIGHTLY cover the service brake pedal while releasing the parking brake
~ Once parking brake is released, apply the service brake fully (HARD!) for 3 - 5 seconds, then release.
If that doesn't release the brakes, try gently rocking the bus in REVERSE.
If that doesn't release the brakes, the shoes are probably rusted to the drums, and it's time to safely block up the body and crawl underneath to "persuade" them. . .
HTH,
RJ
PD4106-2784
Fresno CA |
DaveD (216.18.113.69)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, January 10, 2003 - 9:01 am: | |
What's the outside temperature where you are? Is there moisture which may have turned to ice in your braking system?
DaveD |
Mark R. Obtinario (Cowlitzcoach) (206.163.13.30)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, January 10, 2003 - 9:15 am: | |
I know this discussion has been broached before but you could elaborate on what a DD3 brake system is and how it works?
In particular I would like to know what happens when the air pressure goes down. Does the button pop out like a spring brake systems does?
Thanks.
Mark O. |
Tony G (24.237.70.61)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, January 10, 2003 - 4:51 pm: | |
Here's the MCI service bulletin that should help you understand the DD3 system:
http://www.motorcoach.ca/serinfo/serinfo0700.html
tg |
Art Gill (208.11.184.71)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, January 10, 2003 - 6:16 pm: | |
I have had a similar problem with my Eagle 20 and I was told to pull up on my brake pedal. It solved my proble and it is easy to try.
Art (sandcastle) |
Don Ames (209.244.151.245)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, January 18, 2003 - 12:40 pm: | |
I had this same problem a couple of years ago on my GMC 4903 with the DD3 system. It turned out to be a gummed up relay valve located on the bulkhead in front of the rear axel. The release valve on the dash does not control air directly to the brake canisters but does it via this valve. If it is gummed up as mine was, then the brake canisters do not even know you released the parking brake valve.
Don |