| Author | Message | ||
| Doug Dickinson (Dougd470) (65.161.188.11)
Rating: N/A |
I have an 83 MC9 NJ Transit version with a kneeling feature. THe brakes stay locked and the kneeling feature is messing it up through some interlock. I checked with Luke at US Coach and he advises that there in an interlock between the kneeling feature and the brake system which will explain the locked brakes. I need to disable (remove) the kneeling feature on the coach. Herein is my problem - while I consider myself to be "passable" as a mechanic, I also know my limitations - which in this case is air brakes. I would prefer to have some diagram or information on how to disable/remove the kneeling function on the bus and where it connects to and locks the brakes when in the kneeling position. Anybody have any information/schematics/knowledge they can share? Thanks Doug St Louis '83 MC9 | ||
| MC - Iv (24.83.235.106) Rating: N/A |
I had my kneeling feature disabled. (mc9). It used to stick occasionally in the down position. The bus mechanic who did it for me explained that all he did was bypass the kneeling valve. It only required a couple of air line fittings. He left the valve in place and I will remove it when I have time. It is located approximately between the front wheels. I also replaced the by-parting doors with a single door so I will need to remove the air closing mechanism as well. MCI manual is a must. Iv. | ||
| Buswarrior (Buswarrior) (64.229.212.62)
Rating: N/A |
Hello Doug. Is the kneeling feature messing with the parking brake release, or ????. It depends how the thing is set up, for which quick fix will work. Interlocked with the parking brake, the door, the service brake, and/or what else? Beware: There are a lot of mechanics out there who are not as well versed as they make out to be, and shouldn't be re-engineering the underside of your bus. I'd lay bets that there are many NJT mechanics who can't be trusted to work on them, never mind bypass them. Anyway.... If it isn't the parking brake circuit, I would anticipate that the kneeling feature activates the brakes by use of an electric solenoid valve plumbed in parallel to the brake pedal and works on a service brake circuit. If you find the right wire and cut it, it won't be able to put the brakes on anymore, and you can leave your air system alone until you learn enough to feel confident to remove the offending parts completely. Bypassing the solenoid valve will more than likely be an exercise in plugging or removing two "tees" where the lines run off to it. As an afterthought, I'm wondering if this kneeling system was a NJT retrofit? I'm thinking 1983 is awful early for factory kneeling. MCI might have been starting the air step revolution at that time, but not kneeling. Maybe a phone call to NJT might get a drawing or two headed in your direction? Make it really easy for them, have your e-mail, some fax number and a snail mail address ready. Just have to find a nice person with a minute or two on their hands to help you out. happy coaching! buswarrior | ||
| jmaxwell (66.42.92.21) Rating: N/A |
Buswarrior is onto the right course I think. My '81 Grumman utilized an electric solenoid to activate the kneeling and interlock systems (throttle, brakes) By disconneting the ground to the kneel system electrical circuits, I essentially disabled it. Later incorporated it into a park leveling system and disabled the interlock with the throttle (which required addition of a single jumper on my kneeling switch. You will most likely need schematics to trace the wiring, but you need them anyways. | ||
| Doug Dickinson (Dougd470) (65.161.188.11)
Rating: N/A |
Thanks all. My problem is that the brakes will not readily release when I take the parking brake off, or take my foot off the service brake. I feel backpressure on the service brake pedal, which tells me that there is a "shortcut" that is created when the kneeling feature is deployed (the bus is down). When I raise the bus, it seems like the raise valve is stuck and it is still trying to pump up (up and down - a war between the leveler and the kneeler system). I guess this weekend I will be crawling under a bus and finding out where things go. I was planning on using the front air bags as a leveling device via a couple of regulators, and I may just do that this weekend as one step, rather than re-plumbing things and then re-plumbing again later. I used to work for NJT, but all my contacts are mostly gone. The kneeling feature was MCI installed at the build of the bus. All the NJT buses in that buy were so equipped. I am going to call MCI and see if someone there has a diagram on the kneeling feature. I totally overlooked that! In St Louis, there really isn't much bus use so finding a mechanic is somewhere between difficult and impossible. I had one replace the Brake Relay Valve and he had a time doing it. I had to coach him on bus related stuff, like blocking the body as well as the wheels for safety. Doug St Louis MC9 | ||
| Pete (205.188.209.11)
Rating: N/A |
Ok, I'm willing to try anything once..I'm thinking the kneeling is when the rig sits down and the air ride is deflated. If so, is there a way to bypass it on a GMC 4501 ? I blew out one of the self levelers and bypassed that just fine until I can get it rebuilt but stopping it from kneeling, if thats what I"m talking about would sometimes make life nice. OR, Am I just missing the total thing and need to stop writing..  Pete | ||
| Doug Dickinson (Dougd470) (65.161.188.11)
Rating: N/A |
The saga continues: I called MCI and they were quire helpful, but don't have the exact information I am looking for. Seems nobody made the diagram for the kneeling function on the MC9A (the '83 MC9s that NJT purchased). They DID send me a diagram of the MC9B kneeling feature which will help a lot. I also have the MC12 diagram from MCI and it is similar. Using these two as a concept guide only, I can probably figure this out. |