Hi fellow Foretravelers, my coach has been in storage for quite a while but I'm about to pull it out to begin work on it again. My biggest issue is that the parking brake doesn't work. It's a 1987 Grand Villa 3600 ORED with the 300HP turbo CAT engine. When I pull the "Parking Brake" switch, the air system actuates but it doesn't hold the coach so I can't park it anywhere by myself because of having to chock the wheels to keep her from rolling. This model doesn't have a "Park" selection in the transmission so the parking brake is the only way it will stay in place when parking it.
Questions:
1. Does anyone have a schematic or diagram of the air brake system on the V-917 chassis?
2. Why could this be happening? I'm pretty good with anything mechanical or electrical so troubleshooting this shouldn't be an issue for me if I had a diagram of the system. However, I've never worked on an airbrake system so I don't know how they apply braking force based on air pressure since the air pressures are significantly lower than hydraulic pressure in a standard automobile brake system.
2. Does anyone know where I can find parts for the braking system?
This is obviously my first priority so that I can safely park the coach without assistance. The normal braking seems to work okay so it's just the parking brake mechanism that isn't functioning properly.
Thank you all for reading.
Kirk
I am far from an expert, but have done some limited work on air brake systems. No doubt others will contribute.
In my limited experience, "parking brakes" on air actuated systems use springs to engage the parking brakes. Air is used to hold the springs off the rotors when the parking brake is not engaged or you lose air pressure. When there is no air pressure, the springs are released and apply the parking brakes. If your service brakes work, but the parking brake does not, start by inspecting the spring cans.
It is possible the rig was previously towed and the spring cans were caged...meaning a special T-bolt is used to compress the springs. Might want to Google for youtube on how to cage the springs, but if there is a bolt extending from the middle of the spring can, the brakes have been caged. If that is the case, just remove the bolt.....of course, if they are caged, it could be because the spring cans do not hold the brakes open when air is applied in which case you will need new spring cans.
Parking brake is spring actuated to apply on loss of air pressure. Worn brake shoes? Actuating lever stuck? Has previous owner manually retracted the springs?
Your Spring brakes will not hold if your brakes are out of adjustment. Read up on how to adjust slack adjusters. You'll have to determine whether you have manual or self-adjusting slack adjusters. Even if you have self adjusting you can manually adjust. Parking brakes (spring brakes) rear axle only.
Brake cans can and will break the internal spring. Usually the ones that break are corroded. Can't find the picture of one I thought I posted.
My 87 ORED has double acting cans . Park brake and road brakes use one can with at least 2 air lines. They are wedge brakes and may well need adjusting . One of my park brakes works well and the other side less so.
If this is a new issue ,Check the park knob itself . Loosen the air lines and see if you get any action.
If it has been this way for a while, you may have a spring issue or air restriction ibn the brake system .
Does the bus stop OK ?
You have wedge brakes on that unit so need to study up on how they work and how to work on them.
Thank you all for the rapid responses. I haven't been under the coach since I bought it. The guy I bought it from had been living in it for a while and then parked it in a field for storage. It ran and drove but was otherwise in need of A LOT of cleaning and repair. I took about 10 large, lawn and leaf trash bags of clothes and junk out of it before I could fully assess the interior. Luckily all of the cabinets and wood were in decent shape, no rotting or anything like that but in serious need of a deep cleaning.
Mechanically, it's in fairly good shape. Before I drove it home, I added some Marvel Mystery Oil to the fuel just to make sure the fuel pump and everything would get some lubrication and treatment since it had been sitting and I didn't know for how long. I plan on going through and replacing all of the suspension and steering bushings as well as going through the entire brake system to make sure there are no air leaks. The problem is that I'm having trouble sourcing any diagrams of the braking system or chassis and therefore I can't go source the parts because I don't know what I'm looking for.
Does anyone have any documentation on the V-917 chassis or at least the air brake system?
I suspect my problem is that the parking brake can needs replacing but again, I don't know where I can buy the part nor get a good part number to go find.
I have the same chassis as you ( the Oshkosh V-917) and I do have an air sys diagram but I'm not sure if it is totaly accurate. If you want one I can try to get it to you via email or the forum. No assurances on being able to or on accuracy. Have a great day ---- Fritz