ATTENTION: All Postings that advertise items for sale will be deleted from the Discussion Forum. You may post sale items for free in the Classifieds section. Sign up now.
Wondering if anyone might have had this problem before and could help. I have a 1983 MCI 9 bus that I am doing the conversion on. We are traveling in it as well. Sometimes we can stop somewhere and the parking brake doesn't hold. The air pressure is up where it needs to be and everything seems normal. The brakes were just checked out and they seem to work great. It is just the parking brake and it is only sometimes. Other times it will lock in and hold.
Another clue may be that when the parking brake is acting up the bay door air switch seems to vent differently when you hit the switch. Instead of just the hit of air that you normally hear you hear a constant air release and the button don't stay in.
I think that the MCI 9 works the same way as a MCI5B. If you have to apply the brake with 90 lbs pressure to release the parking brake, they are the same. They work on a special brake canister that has a set of mechanical rollers & ramps that locks the brakes on. They can get rusty and not engage. The canister would have to be rebuilt. Mine got so rusty that when I applied the brakes while I was driving, it wouldn’t release.
The spring brake that someone described is the way a truck system works, busses are different, and they apply with air.
presure not spring presure.
You need to post this question on the "mechanics" forum. A guy named "Joe" will know just what ails your brakes. However, as I understand the parking brakes, you must first apply the service brakes and then pull the parking brake knob. My MCI 9 owners manual states such. I can also advise you that my MCI 9 parking brakes will apply even when you don't apply the service brakes (I didn't know about this when I bought the bus). Your parking brakes should apply whenever the the brake boosters don't have air available to them. A big spring in each booster is what applies the parking brake. That's why they will hold after all the air has leaked down. Your brakes do apply when your air is down? Joe will straighten this out! Good luck.
email Keith
reply to message
post new message
search forums
