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Old 05-02-2012, 02:43 PM   #1
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Parking Brake

My parking brake works fine when cold. When warm it will not hold the home on a hill. I read all the previous inputs and passed them on to my repair guy. This is his response:
I think we are a little past these kinds of repair. There is a problem with a component on yours, (Stretched Cable, air cylinder, Pad thickness ) or something like that. The type of brake that you have is also very unusual. It pushes on the center of the pads, not on the ends. When they arc your shoes they arc them as though they are for end push not center push. This causes them not to touch on the ends.

If any of you have any additional info I would greatly appreciate it as I have not had any good answers from the repair guy since they cannot figure out what is wrong. One guy told me the whole brake system is the same as used on Chevy trucks. That is not what I was told when I purchased the coach. Any comments Please.

Joe Brunold
2006 Alpine Apex 40' 4 slides
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Old 05-02-2012, 03:59 PM   #2
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You have to apply some "reverse-logic" when understanding/diagnosing how our parking brakes work. When engaged, the brake pads are held against the brake drum by spring tension. To release the brake you apply air to the air cylinder which in turn pulls the cable which in turn pulls the pads away from the drum. So, if the brake isnt holding [warm vs cold is a bit confusing] but never the less, if its not holding, either a spring/springs are bad/unhooked, the pads are worn [suppose this could happen if cable had stretched allowing pads to drag while you drove], or the cable and air cylinder are somehow hanging up and not allowing the pads to fully contact the drum.

Never tried it but have heard there is some adjustment of the brake--probably just the cable though. If the pads have been dragging over a long period of time this could explain the reported wear. Hopefully, someone will have more to add but it seems like the springs would continue to apply pressure to the pads until they literally wore thru. Your repair guys sounds like he knows what he is doing but make sure he isnt tightening the cable in hopes of causing more brake pressure--infact its just the opposite direction!!!!!

As for the comparison to Chevy trucks--I suppose the drive line parking brake system used on large Chevy trucks could be similar but that is a totally different conversation from the 4 wheel hydraulic/disk brakes we use for stopping.

Last thought--an air leak at the brake control valve could result in some air getting thru to the cylinder but this is unlikely.
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Old 05-02-2012, 06:54 PM   #3
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Could be that the air actuator is not fully actuating, and brakes are dragging; that would imply a leak or some other detectable problem.

I too am not sure what it is that is "warm" that goes w/brake not holding. A better explanation might engender better feedback.
Couldn't say if same setup is used on Chevy. I suspect something quite close is on MCI and other buses. Spartan uses what I believe is the same brake on its motorhome chassis (note the Allison case in the drawing), tho not the 90 degree cable housing for air release of brake; Spartan's is direct drive release of air cylinder while WRV's is 90 degree by cable to drive the release.

Check out the final findings here (starts around post#67) on Old Forester's 06 low air issue. His problem was w/the brake actuator leaking.
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Old 05-04-2012, 11:23 PM   #4
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Sold the coach but still look at the forum occasionally. Saw E-Mike's comments. If the pads looked like they had lining, first place I'd go is to the brake actuator (called a roto-chamber). Mine leaked air around the seal on the chamber and wouldn't fully pull the brake off. Possible the spring in your rotochamber is worn and expands enough when warm that it doesn't put enough pressure on brake pads. There is an adjustment on the clevis-type connector that attaches to the brake cable. It can be released when air is on the actuator by removing the pin (better have the coach on a flat surface and well chocked and on jack stands or similar) and then screwing the clevis tighter on the connecting rod to take up some slack. Be careful not to let the air off the system or have the spring snap the actuator shut when you have your fingers in the way.

The rotochamber can be rebuilt. Had mine done by Colton Truck Supply, in San Bernadino, CA, phone (909) 888-8300. They make it work and look just like new, and get it done in a few days.

If the rotochamber holds air pressure and has a strong spring, there's plenty of force to grab the pads on the driveline, and release them, and the pads would have to be well worn or not making contact with the driveline when engaged, e.g., namely not adjusted, for the brake not to hold.
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Old 05-12-2012, 10:22 AM   #5
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Does anyone have a diagram and manuf. name of our parking brake ? Tks. Don P. 01 38 FDDS OOPS 02
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Old 05-13-2012, 07:16 AM   #6
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I have a repair shop putting a new one on my coach and hopefully I will have it back by Tuesday and I can let you know if it works and who makes it.
Joe Brunold
2006 Alpine Apex
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Old 05-13-2012, 09:01 AM   #7
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alpine park brake

does anybody know what an Alpine automatic parking brake switch bypass
1xa-w404 Inaw404-w-900 pac tr7 is ???
Is this even talking about an Alpine coach.
I saw these on ebay during my frustrated search etc. Tks. Don P.
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Old 05-13-2012, 11:04 AM   #8
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Don- that eBay listing has to do with Alpine stereo/audio equipment, not WRV and Alpine Coach. Hopefully Joe will have the info for us.

On your 01, does the parking brake actuate thru a 90 degree cable setup?
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Old 05-14-2012, 08:31 AM   #9
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E Mike, I made an error on year I'm an 02.

I think mine does come in in the 90. I'll have to double check this afternoon when I'm back under it. Then I'll confirm. Tks. Don P.

Tks. for the clairification on the stereo bypass, I suspected as much.
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Old 05-16-2012, 06:32 PM   #10
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I started having the the low air supply warning about a year or so back, mostly when the outside air temp got below 50, now its getting worse. I have a 2006 Alpine Limited.

I appreciate all the info and EngineerMike, I appreciate your post from #67 back and I will look into the air dryer issue. I took the coach to Cummins service near me. They couldn't figure it out. They thought it might be a leaking pressure switch because they couldn't replicate the problem.

What I would like to know, is there a drawing or breakdown schematic of the components in the Alpine Coach air system. I'm afriad I'm the kind of guy who likes to see and know where each component is.
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Old 05-16-2012, 08:04 PM   #11
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We've never gotten a factory air schematic, would love to have that and chassis hydraulic for problem solving purposes.
Old Forester started a crude one when working out his chassis air issue, and sent me the work in progress. I'll hafta clean it up (came as a mostly readable fax) and post it, so you fellers can work out the kinks and let me know what the real final version should show. There has to be at least one check valve in the system to keep air in the tank, but that isn't shown.
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Old 05-16-2012, 08:28 PM   #12
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Here is Old Forester's preliminary work on air schematic:
Attached Files
File Type: pdf Chassis Air Schematic Preliminary 5.16.12.pdf (29.5 KB, 206 views)
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Old 05-17-2012, 11:08 AM   #13
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E-Mike:

Nice work on the schematic. I was just thinking I needed to clean that copy up that I sent you last year, but you did a nice job of putting it together. From my memory, there's something I've missed but I don't think it's significant. The crude diagram I made up I gave to the new owner of my coach.

JacobsCanyon, I'll send you a PM with my phone number and ask you to give me a call. We fought that cold air low suspension problem for most of the first 4 years we owned our '06. Cummins repair shops and other major coach repair facilities couldn't find the problem as well. I learned our problem was impossible to diagnose when the air temperature was up or the engine got warm, which is when we usually have it at the repair facility. I finally got it effectively diagnosed over 3 trips to a smaller RV dealer who had a couple ex-big truck mechanics, in Georgetown, TX, when the temperature finally dropped to 20 to 25 degrees, the engine hadn't warmed up and the warning buzzer was going off consistently.

We replaced the air dryer cartridge, the quick release valve, and looked hard at the dump valves. None of these solved the problem. When it was finally cold, a mechanic crawled under the coach with the engine running, parking brake off, and me in the driver's seat with my foot on the chassis brake pedal. That's when he felt around with his hands on all the air connections and found the roto-chamber (parking brake actuator) was leaking on the top side of the chamber, where you couldn't see the leak from the ground. The chamber is in two pieces and it leaked where the top part connected to the bottom part, with some sealant-type material oozing out. When the chamber warmed up, the inner chamber expanded and closed off the leak.

We replaced the roto-chamber with one from a wrecked Alpine and the leak stopped; never leaked or had the issue in the year and a half since, including some very cold mornings. Had the leaking one rebuilt at Colton Truck Supply in Colton, CA, as a spare; only cost about $150.

Attached is a photo of the roto-chamber with the leaking area shown at the bottom.

So, if it were me, I would go look at your roto-chamber and look/feel around it to see if you have a similar leak. I would also look at the quick release valve to see if it were leaking, but I'll just about bet you have the same problem as me. My coach VIN was 75561; would be interesting to know if yours was built close to mine.
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Old 05-17-2012, 06:23 PM   #14
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Hey guys thank you, please call me Dan. I don't know why I used the JacobsCanyon handle when I set this up. I took the air dryer apart today and have a new cartridge coming in next wednesday, it is probably the original cartridge. With my limited knowledge, I thought it looked bad, saturated with oil.

Old Forester, I hate to bother you with a call, but to be sure, the roto chamber info is much appreciated. I'll check it if I can figure out how to get my generous proportions under there. I didn't even know the coach had an air dryer. It is behind the air cleaner and relatively easy to get to. Thanks for the schematic. Can a new roto-chamber be purchased if in fact I have the same problem.

FYI to share a different problem with my coach and power supply from the automatic switch. There is a eight inch power box above the gen set. You can't get to it unless the gen is out. The pig tail from the gen attaches to the main line to the Auto Switch cable at this point. I wasn't able to get gen power at a dry camp at Lake Powell, 104 degrees of course. I traced it to this eight inch box. To make a long story short, the factory put wire nuts that were to small. It had burner apart two of the wire nuts and could have easily burn down my coach. So I put very small stainless steel hose clamps on temporary because there were no large wire nuts within 150 miles. Worked great and I repaired them in my garage, watching my large self climb up under there would have been a you tube moment.

Also Old Forester, my coach is a 2006 and the number is 75563, don't think I could get much closer to yours.
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