| Author | Message | ||
| Kevin Black (Kblackav8or)
Registered Member Username: Kblackav8or Post Number: 85 Registered: 8-2005 Posted From: 24.152.174.198 Rating: |
Out of curiousity and having never seen one in person, what does the front suspension of a bus look like? Are there Air suspensions? Torsion bar? Leaf spring? Any links to pictures? | ||
| Paul Lawry (Dreamscape)
Registered Member Username: Dreamscape Post Number: 178 Registered: 5-2007 Posted From: 64.40.222.139 Rating: N/A |
All depends on the make of the bus. Some are air, torsilastic, older ones are leaf. What are you looking for? | ||
| Kevin Black (Kblackav8or)
Registered Member Username: Kblackav8or Post Number: 86 Registered: 8-2005 Posted From: 138.163.0.43 Rating: N/A |
I would like to see what the air suspensions look like. | ||
| RJ Long (Rjlong)
Registered Member Username: Rjlong Post Number: 1335 Registered: 12-2000 Posted From: 67.181.166.160 Rating: N/A |
Kevin - Since it appears that you're in the San Diego area, there are lots of charter companies, plus the transit system, down there. Meander over to one of their yards and ask to speak to the shop foreman. Tell him what you're interested in, and offer to buy him lunch if he'll give you a tour of a coach either on a hoist or over a pit. Another option would be to contact Scott at Regional Transit Services - "The Movie Bus People" - out in Riverside, and share with him your interest. Scott's business is a little slow right now due to the entertainment industry's writer's strike, so he might have the time to visit and share with you. This would be a good place to see several types of front air suspensions, as Scott's got a lot of different models in his fleet - old and new. Sorry, I don't have his phone number handy, but Google his business and you'll get a link to his website, which does have contact info. BTW, the rear air suspension on a coach is usually different than on your KW, so you'd want to look a that, also. Some transits (mainly early Gilligs) use off-the-shelf HD truck suspensions, so check out the back axle, too. FWIW & HTH. . .  | ||
| David Dulmage (Daved)
Registered Member Username: Daved Post Number: 184 Registered: 12-2003 Posted From: 142.46.199.30 Rating: N/A |
MC-8s have a forged front axle. Suspension on the front consists of 4 convoluted style air bags, located two per side, one ahead of and one behind the axle. The airbags are located below air beams which are chambers that provide additional air volume and provide for a smooth ride. The air beams are made of heavy gauge mild steel, but can, over time, develop pinholes and and leak air. MCI, among others, offers kits to block off the air beams and replace the convulted style air bags with rolling lobe type. The roling lobe type air bags are supposed to give similar ride charactaristics as the convoluted air bag/air beam combinations. The front axle is located by radius rods. There is one levelling valve for the front suspension and two for the rear suspension. Dave D | ||
| Luvrbus (Luvrbus)
Registered Member Username: Luvrbus Post Number: 167 Registered: 8-2006 Posted From: 74.32.87.162 Rating: N/A |
Kevin,the Eagle has no front axle but two torsilastic on the lower frame on each side and A frames on the top of each wheel and work independantly of each other like a automobile so you get the Eagle ride | ||
| Chuck Newman (Chuck_newman)
Registered Member Username: Chuck_newman Post Number: 242 Registered: 1-2005 Posted From: 63.145.177.245 Rating: N/A |
Kevin, Another surprise you may get is some buses (at least my MCI 102A3) has only a single air system vs your tractor's dual air system. Does anyone know why this is so? Does the single system pertain to all buses? | ||
| RJ Long (Rjlong)
Registered Member Username: Rjlong Post Number: 1337 Registered: 12-2000 Posted From: 67.181.166.160 Rating: N/A |
Chuck - Do you have a single or double needle air pressure gauge? Chances are, even if you've got a single needle gauge, based on the vintage of your coach, it's probably a dual air system. Time to dig out the schematics and take a closer look. Most coaches went to dual air systems in the middle-late '70s. FWIW & HTH. . . | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1115 Registered: 12-2000 Posted From: 76.68.122.41 Rating: N/A |
Hello. The use of dual air systems came into effect during 1975. The actual specifics of the requirement demand certain performance under certain types of failures. It is common to use a dual air system to accomplish the required performance, but not mandatory, if one can figure out some other way. By continuing to use the DD3 system and it's service/parking split, MCI was able to continue using a single needle air gauge and fulfil the letter of the law. happy coaching! buswarrior | ||
| Chuck Newman (Chuck_newman)
Registered Member Username: Chuck_newman Post Number: 243 Registered: 1-2005 Posted From: 67.126.86.142 Rating: N/A |
RJ and Buswarrior, Sorry guys I've been tied up the last few days on another project. Anyway, RJ to answer your question, the 102 has only one needle. I have the air diagrams. Compressor to dryer, dryer to wet tank, wet tank to dry tank, dry tank to A)accessory tank (wipers, etc.), B) park brake tank, C) valves, bags, air gauge, etc. It has 4 tanks. When I studied the layout I was surprised. I expected to see a tractor/trailer parallel tank configuration (red & blue) like shown in the DMV manual and the Bendix Brake Manual. Not so. The only thing I not sure about is the "Park Brake" tank. I'm guessing it substitutes for the "secondary" air tank on a truck. Comments?? Buswarrior, if I am reading your last sentence correctly, then I presume this park brake tank figures into that equation. What do you think? Thank you both for the input. PS: RJ, It's been hectic here the last week, and we will be gone much of the weekend. If I get a chance, I'll call you this weekend. Thanks again. | ||
| Kevin Black (Kblackav8or)
Registered Member Username: Kblackav8or Post Number: 87 Registered: 8-2005 Posted From: 24.152.174.198 Rating: N/A |
The MC-8 systems sounds similar to the Kenworths Airglide system. My rear has 8 air bags, 4 per axle with the airbags working through underslung beams. I am just curious since I use mine as a RV hauler maybe sneaking something from a bus to smooth out the front ride. My truck has 3 air tanks and brakes on all axles. It also has a guage for suspension pressure. I have never seen it over 15-20psi. Actually my truck rides quite good for a truck. On a side note a friend of mine has a older KW like mine that has been fully converted into an RV that has achieved 14 MPG before with a Cummins 400 and a 13 speed. I am hoping my new 15 speed and 1550 rpm cruise rpm will push my MPG up. http://youtube.com/watch?v=r0UljDne4xU | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1117 Registered: 12-2000 Posted From: 76.66.16.89 Rating: N/A |
Hello Chuck The parking tank is isolated from other parts of the system by way of a one way check valve. Your parking brake is air activated, and locked on mechanically by the DD3 chambers on the drive axle. Elsewhere on your schematic, you will note a "shuttle" valve in the service brake circuit, that accesses air from seperate circuits. In this short description, under some type of air system failure, there is duplication giving you more than one way to get some brakes to apply. The result is the same as the theories in most air brake training literature. Even if there is a wildly popular way to skin a cat, there are other ways! When the "DD3 Safety Actuator" was first available, it offered a greater level of safety as it had isolated sections in the air system. The traditional single circuit brakes of that day had service chambers at each wheel, all being activated by the same air source. No air, meant no brakes! Parking brakes back then were not very effective driveline affairs. MCI remained committed to the DD3 system up until only a few short years ago, in part being driven to spring brakes and dual air circuits by the dramatically lower cost of the more readily available spring brake components. happy coaching! buswarrior |
