| Author | Message | |||
| L James Jones Jr (Jamo)
Registered Member Username: Jamo Post Number: 40 Registered: 11-2007 Posted From: 74.79.238.13  Rating: N/A |
I've been keeping up with the posts on the DD3/Spring/Maxi brake thread. After all the reading, I'm still not sure of the basic mechanical differences between the DD3/Spring/Maxi systems. As I see it, my 4104 originally had a system that would allow the bus to roll with no air in the system, right? What was that OEM setup called? My bus has been converted to what I thought was spring brakes. Needs 60# to release the popper. What do I look for to see if I have Spring/DD3/Maxis?? For all I know, I have Ron Popeils pocket popper bus stoppers. No arguements here...just looking for the basics if you would. Just the facts, M'am. Thanks..... Jamo | |||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 404 Registered: 8-2006 Posted From: 207.231.75.253 Rating: N/A |
Jim, Here's what you asked for. 1. Springs and Maxis are the same thing. 2. DD3s came about in the mid 60s, first as an option, then within a couple of years as a standard replacement for the handbrake. 3. Maxis came about years later, and are now the only system sold new on all air brake vehicles. 4. In addition to the service brake system, DD3s have an additional reservoir protected by a check valve. This prevents the emergency reservoir from being depleted in case of a piping failure upstream from it. DD3s also have a second chamber and diaphragm on the drive axle brakes, and an air operated "latching" mechanism, which takes air pressure to release. So, in the release position of the knob, the latch line is charged, and the parking/emergency line and chambers are released. "Popping the knob" releases the latch line pressure, and applies parking/emergency reservoir pressure to the parking chambers. This application is mechanically held on by the latching mechanism, and will remain applied if/when all air has leaked out of the bus. Some buses were ordered from the factory with an option which required a 100 lb foot pedal application to release the brakes after the knob was depressed. 5. Maxis or springs do the same thing with less parts. They have two chambers, and a large, strong spring. In the release position, air is supplied to the parking/emergency chamber. This pressure overcomes the spring tension, and releases the brakes. Popping the knob releases the pressure, and the springs apply and hold the brakes applied. Simple. The real easy way to tell which you have, is to pop the knob. If you hear a large exhaust of air from the rear, you have Maxis. Essentially a silent application means DD3s. A positive means of verification is to go under, AFTER BLOCKING THE BUS SECURELY WITH QUALITY BLOCKING MATERIAL AT THE JACKING POINTS, and count the hoses going to the rear cylinders. Two=Maxis, 3=DD3s. Don't ever go under an air ride bus, OR between the tires and the wheel wells, without blocking it up securely. The danger, IMNSHO, is not so much an air bag exploding, as it is the bus simply settling down on you as the air leaks off. We want you around! Nobody told me when I was new, (way before the internet) the used bus dealer didn't either, and I'm lucky not to have been squished. George | |||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 1020 Registered: 10-2003 Posted From: 71.58.48.5  Rating: N/A |
DD3's have three hoses; spring brakes have two. You have to supply a full air pressure treadle application to release dd3's; spring brakes, you just push the button. | |||
| Larry Hurd (Lghurd)
Registered Member Username: Lghurd Post Number: 1 Registered: 4-2008 Posted From: 71.96.30.196 Rating: N/A |
John I saw you on this and other posts about brakes. Thought I would see if you could answer something for me. Although the original post here only has some element of my problem I wasnt sure that my problem needed a new thread. So here goes. I have a 1968 eagle...My coach operates opposite of the way I understand air brakes to be. If my coach has no air it will roll freely. When the pressure starts to build the brakes start dragging and eventually will not allow the bus to move after pressure is way up. So when I need to move it(around the storage yard) I have to do it before pressure builds which is not a good thing since then I dont have brakes at all. I feel this may be a two-fold problem 1. the parking brake does not seem to be setting at all or releasing when I try it. 2, It seems like the service brakes may be applying as pressure builds. I have tried building up pressure past 120 psi and applying service brakes with parking brake released. No luck. Any thoughts on what to do to fix? Thx Larry | |||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1250 Registered: 12-2000 Posted From: 76.69.141.132  Rating: N/A |
Better to use the generic term "spring brake", Maxi was a brand name, and as this thread shows, leads the novice into believing there are more parking brake options. All DD3 chambers will require a hard service brake application, IF the air pressure in the parking tank has dropped below the pressure that it was applied at. So, if you stop, apply the DD3 and then release it, it will release without a service brake application. Leave the coach for whatever time it takes for the air to leak away, and it will need a squeeze to get the DD3 locking rollers to come away from the shaft and allow a release of the latching mechanism. Since you have no way of seeing the pressure in the parking tank, because the air pressure gauge on the dashboard is plumbed into the system elsewhere, the common wisdom is to make the full service brake application on all releases, to ensure that you do not leave a brake dragging with a partial release. These are subtle nuances, but critical if you are going to attempt to diagnose problems, and the coach does things which are normal, but contrary to the popular practices. Larry, block the wheels on your bus, and don't be moving it until you have someone onsite who can properly diagnose your problem. That bus has some serious safety issues that will not be easily diagnosed via the internet. Go around the local bus garage and see who wants to make some ca$h giving you a hand. happy coaching! buswarrior | |||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 1029 Registered: 10-2003 Posted From: 71.58.48.5 Rating: N/A |
Interesting problem... do the rear chambers have three hoses? Has this coach set a lot? Did this show up after some brake repairs? Do the rear chambers have two hoses per. Is there a drum on the drive shaft with a brake chamber attached to it via linkage? Spring brakes, if it has them could be backed off. I have no idea what your coach has for brake systems, so these suggestions are just my speculation at this point. | |||
| Larry Hurd (Lghurd)
Registered Member Username: Lghurd Post Number: 2 Registered: 4-2008 Posted From: 71.96.30.196 Rating: N/A |
John, I didnt make it over to coach in order to verify how many hoses today but I believe it has the DD3's. It has been sitting for a while. There was not any brake work done prior to this problem. There isn't a drum on the drive shaft. I am sure the part about being parked a while is where the problem stems from. Buswarrior Thx but outside help is not an option right now with finances. I am very handy and very cautious so I intend to try to learn what may be possible on my part. It may be the difference in selling now or being able to get back to making a gem, but warning taken. Thx Larry | |||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1254 Registered: 12-2000 Posted From: 76.69.141.132 Rating: N/A |
Hello Larry, Here's some thinking out loud for you. If we assume that the locking rollers/circuit in both DD3 chambers have failed somehow, they will not latch the brakes in the applied position once the parking supply tank leaks down. So, after shut down, as the air leaks, the brakes release, so it can freely roll. Once the engine is started, and air pressure starts building, the parking supply will begin to apply air to the parking diaphragm, slowly increasing the squeeze on the brake shoes as the air pressure builds in the coach. Which is how you described the bus behaving. But you can't get a parking brake release either... Now, what will trigger these manifestations? Way too big a coincidence to have both chambers fail to lock and fail to release for it to be a mechanical problem in each chamber at the same time. One place to check would be the function of the inversion valve, but how would it manage to pressurize the wrong parts when it isn't pressurizing the right parts without pouring air overboard out its exhaust at a rate that would prevent the bus from airing up? This still sounds fishy. Hmmm, or how about this? The DD3 system is working fine, but the drive axle brakes are way out of adjustment, (which is not good, have to figure out why later) it's the service brake system that is causing grief, due to some stuck relay valve or the brake pedal valve being stuck on, which would produce the same symptoms as you described. Try checking this: Look/mark the position of all the slack adjusters, front, back and tag/bogie, start the bus, and see what moves to the applied position when the air builds. If they all move, and the DD3 chambers stroke out beyond 2 3/4 inches, the brake pedal valve is the culprit, and the rears are not touching. Let us know, and keep that beast's wheels blocked! happy coaching! buswarrior | |||
| Larry Hurd (Lghurd)
Registered Member Username: Lghurd Post Number: 3 Registered: 4-2008 Posted From: 71.96.30.196 Rating: N/A |
Buswarrior I did find a relay valve(R8) leaking air out of the exhaust continually. It is located under the floor in between the drive wheels. Not sure where to look for the inversion valve you mentioned. Coach will build air at a fair rate to about 60 pounds but it takes some time and work to get up to 100. I used a small 2 horse electric air compressor to try to build pressure so I wouldnt need to run the bus engine. I hooked into Aux air inlet on frt of coach, but couldn't get pressure over 30 pounds. I will check the slack adjusters next time I go to coach. What do you mean when you say "and the rears are not touching"? If it is a faulty valve, can it be cleaned or rebuilt? Thx Larry | |||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1255 Registered: 12-2000 Posted From: 76.66.17.36 Rating: N/A |
Hello Larry. The inversion valve has four of the six airlines from the DD3 brake chambers running from it. Mounted above the differential on an MCI. It does not take that big a leak to defeat the air compressor. A hole the size of the pencil lead in one of those fat primary pencils the kids use at school will prevent the coach from reaching full pressure. For that relay valve, my recommendation would be to buy a new one, because I don't see the cost-benefit of getting a rebuild kit, and there's more to evaluating a defective relay valve body than slapping new parts in it. But that's just me. Commercial fleets are not rebuilding valves these days, they just replace. Price it both ways and decide if your time is worth the difference. When it comes to brake adjustment, there is more brake shoe lining than there is mechanical movement in the brake linkage. Over the life of the linings, the mechanical parts will have to be re-adjusted a number of times to keep the linings close enough to the drum surface to squeeze properly. Hence, the suggestion that if you see maximum brake chamber stroke, which is 2 3/4 inches for a DD3 chamber, the rear linings won't be effectively touching the drums, meaning little to no stopping action on those wheels. Moving forward, the brakes need to be regularly checked and re-adjusted according to use. Having the mechanical parts "stroke" longer than allowed and/or all the way to the end of their travel is a dangerous situation, since you want all those brakes to be squeezing and rubbing as the manufacturer intended to stop the coach properly. happy coaching! buswarrior | |||
| Tony Gojenola (Akbusnut)
Registered Member Username: Akbusnut Post Number: 19 Registered: 11-2006 Posted From: 208.98.151.220 Rating: N/A |
Larry - the symptome you describe are the same as I once experienced with my gm 4106 after upgrading to an E-3 treadle valve. It turned out that the roller wheel under the treadle was out of round, and when it rolled over to the high side, the service brakes were applied. I increased the clearance and it went away. Check the treadle valve for free movement (the hinge pins rust up at times.) Make sure you have clearance at the top of the valve, and also look uner the heel to make sure your long-lost tool or part isn't stuck under it. tg | |||
| Larry Hurd (Lghurd)
Registered Member Username: Lghurd Post Number: 4 Registered: 4-2008 Posted From: 71.96.30.196 Rating: N/A |
Buswarrior Thx I am headed over to coach today so I'll check on all you suggested. That relay valve is in a bad place so will have to pull the duels off to get to it. Will need to borrow impact from one of my trucker friends so it may be a couple days to change that out. Will see about all the others possibilities till then. Tony Thx is the treadle valve the same as the brake pedal valve? | |||
| Larry Hurd (Lghurd)
Registered Member Username: Lghurd Post Number: 5 Registered: 4-2008 Posted From: 71.96.30.196 Rating: N/A |
Buswarrior I also noticed some black oil in air tanks (not a lot but some). Figure its the compressor but can't replace just yet. Is that where the oil would be coming from? Could that possibly be causing some problems with the valves in the air system also? Also should I try to run something thru the system to help clean this up now or at least after a redo on compressor? | |||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 1030 Registered: 10-2003 Posted From: 71.58.48.5 Rating: N/A |
Hard to tell if the oil has been in there long. To really get it drained, leave the drain valves open for two or three days. That will really get it all out. Sort of like getting all the oil out of a oil jug. Then close valves and monitor how much running time it takes to accumulate that much oil. Someone may have backed off the brakes at some time because they couldn't get the DD3's to release, either by not knowing how to properly release them or they are malfunctioning from lack of use. If that coach has set a long time, you may want to go over the complete system to make sure it's reliable. Things like drum diameter meeting specs, camshaft bushing wear, lining depth and condition, slack adjuster condition, etc. need to be checked and or replaced/ reconditioned. If you are handy, some of those brake component rebuild kits are reasonable, and some rebuilt components are reasonable. Rebuilt dd3's are about $450 each exchange. About $225 to $250 in parts to rebuild the pair.Get yourself some shop manuals for the coach and the air systems before you get carried away. You don't wan't to screw up on a repair on one of these babies. Check Bendix online to down load a brake system component repair and rebuild manual. Luke and others can get the parts you may need. Also Mohawk is a good source. | |||
| Larry Hurd (Lghurd)
Registered Member Username: Lghurd Post Number: 6 Registered: 4-2008 Posted From: 71.96.30.196 Rating: N/A |
John Already got bus manuals and took a look at the Bendix and Mohawk site. Great info! Not sure if I'll try to rebuild myself. Sounds much cheaper and also would like to understand how these brake parts operate exactly. Just don't want to be missing a trick that isn't covered in manual. Real world is always a little different. We'll see. Right now I just want to see about fixing this immediate problem of brakes not releasing on high air and not holding after air down. The coach needs to be moved pretty quick so trying to get her safe at least on this service brake side. It'll be blocked again immediatley after I move. I will check all you said to determine what I have and get it narrowed down. Thx again John.....Larry | |||
| JR Lynch (Njt5047)
Registered Member Username: Njt5047 Post Number: 232 Registered: 7-2006 Posted From: 69.132.233.230 Rating: N/A |
Larry, if you remove the R8 valve, or any other valve with multiple inlets and outlets, take a pix or clearly mark the lines so that they are re-connected to the correct port. Some new valves may be "clocked" different from your existing valve. Repositioning of new valves may be necessary. Any plugs must also be returned to the correct ports. JR | |||
| Larry Hurd (Lghurd)
Registered Member Username: Lghurd Post Number: 7 Registered: 4-2008 Posted From: 71.96.30.196 Rating: N/A |
John I did check...I do have DD3's for sure.(has 3 hoses) Buswarrior - Well I marked all the slack adjusters and none (frt, bogie, or drive) moved as the pressure built up. With no pressure I was able to move slack adjusters on front and bogie wheels slightly and I could see linings moving slightly. Not so with drive wheels. Linings were right up against drums whether pressure or no pressure. When pressure goes down they don't seem to move but you can hear the creaking as the coach will roll slightly. I found the inversion valve you talked about. It is in same place as MCI.(on differnetial) Can't tell how well its working yet, but I did notice the other line coming off the DD3's go up to that relay valve that is leaking out of exhaust. (of the 3 lines- 2 go to inversion valve like you said, other to relay valve). So I'll be checking DD3 system and trying to be sure to stop leaks in system. I'll be doing some greasing and cleaning and possibly replacing valves. Thx Larry | |||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1260 Registered: 12-2000 Posted From: 76.66.17.97 Rating: N/A |
Fascinating conditions you are experiencing, Larry. Keep us informed as to what happens next. My curiosity is piqued, fer shure! happy coaching! buswarrior | |||
| Larry Hurd (Lghurd)
Registered Member Username: Lghurd Post Number: 8 Registered: 4-2008 Posted From: 71.96.30.196 Rating: N/A |
JR Yea was gonna mark lines but the camera is a very good idea. As far as the "clocking" of the valves I saw some pictures at a brake parts shop that made me think I might run into prob ur talking about. They didn't have an R8 in stock but can get it in a day. Did some reading on Bendix site and looks like you can "clock" the R8 valve to match your application. Buswarrior Will keep you informed, Thx Larry | |||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 411 Registered: 8-2006 Posted From: 207.231.75.253 Rating: N/A |
Larry, You've got a whole bunch of us really interested in what's wrong. You've got to post back when you get it fixed! From your description of what you found: Valve leaking, and the fact that you can move both tag and front adjuster arms, and not the drive axle arms. That leads me to beleive that one problem is that the drive axle brakes are dangerously out of adjustment, to the point that the DD3 locking rollers no longer can hold the linings against the drums. There was a post a while back where a fellow nut had to apply the foot brake when he APPLIED the DD3s in order to get them to hold. A whole bunch of us had a real issue with that, and it turned out that even though "I adjust my brakes every year," the drive axle brakes were so out of adjustment that the parking diaphragms were at the very end of their travel and the locking rollers couldn't hold the application. You should be able to build and hold air with a moderately sized electric compressor, and neither the inversion valve, nor a relay valve should exhaust any air under normal circumstances. You have told us that "the drive axle stays applied," so I don't think it is locking roller failures on both sides. BW & I have the same opinion about a failure of both DD3 locking rollers at the same time, and although I don't think that's the problem either, consider this: What if one side failed a year ago? You probably wouldn't notice anything wrong, until the second side failed... The inversion valve will not allow a DD3 release until pressure is above ABOUT 80 lbs in all the brake reservoirs, and we don't know exactly where the dash gauges are plumbed in, so we don't know if the inversion valve is indeed seeing sufficient pressure to allow a release. Will the parking knob stay depressed when you have over 90 psi? My suggestions: 1. Replace the relay valve. (That was a no-brainer wasn't it.) 2. Start up, charge up, push the knob, and if it stays in, depress and release the treadle/foot valve, and see if you get a release. 3. If you do, make some arrangement to properly block the bus from rolling, AND TO PREVENT AN EMERGENCY APPLICATION FROM OCCURRING WHILE YOU ARE WORKING ON THE DRIVE AXLE SLACK ADJUSTERS, eg: leave the engine running, or an electric compressor that can hold pressure up. Proper brake adjustment will not allow the slack adjuster arms to move more than 3/4 of an inch, before the shoes are tightly against the drums! You can check the travel by moving the arms with something like a pair of channel locks, etc. The other thing to be VERY careful of, is where you apply "outside" air to the bus. They are all built with several check valves, and a protection valve that doesn't allow air to the auxiliaries until ALL the brake reservoirs, including the DD3 reservoir have about 80 psi. So, if you put air in the front, you may not charge all of the reservoirs due to check valves, and an emergency application might occur later, and pinch you or worse, even though you have a compressor applied to the front, and the bus now appears to hold air! Apply the air to the reservoir that has the air compressor output line connected to it, and you can't go wrong. This reservoir is also known as the "wet" reservoir, for obvious reasons. 4. If you're sure you have at least 90 psi in all reservoirs, and you still don't get a release, it sounds like the inversion valve has failed also. BTW, what State are you in? Post back, please! George | |||
| Larry Hurd (Lghurd)
Registered Member Username: Lghurd Post Number: 9 Registered: 4-2008 Posted From: 71.96.30.196 Rating: N/A |
George Thx for the info. I had suspected that air didn't flow everywhere because of check valves, so thanks for letting me how the system builds. I had put a male quick connect on frt aux air supply inlet so I could use electric compressor easier. Then later I started the coach without capping off the quick connect yet. When I went up to put on a quick cap I'd made up I realized no air was coming out anyway. Figured it was prob a check valve. I went ahead and capped off anyway in case it charged later. So what you said makes all that more logical. Yea the button for the parking brake does stay in after I get past about 60 pounds. Coach will get pressure up to about 90-100 on a very fast idle. Only could get to 125 once when I used elec and coach compressor together. Just wanted to be sure to get higher pressure than when locks were set previously. I depressed and released treadle a few times with parking brake knob pushed in. No luck. The relay valve is a big target for me now but there are a couple other things I am going to do before I get there. I want to try these separate if possible so I can see what really fixed the problem. Besides the relay is very hard to get at right now. Will be a couple days before I get back over there to try again. I live Texas. Thx Larry | |||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 1037 Registered: 10-2003 Posted From: 71.58.48.5 Rating: N/A |
Oh, maybe someone has flipped those release levers at the slack adjusters to release the dd3's to move the coach. ( if it has these like my 4905 ) | |||
| Larry Hurd (Lghurd)
Registered Member Username: Lghurd Post Number: 10 Registered: 4-2008 Posted From: 71.96.30.196 Rating: N/A |
John Tell me about these release levers. I will check on my coach but don't remember seeing anything that look like a release lever. We are talking about the slack adjusters that are hooked right to the DD3 chambers, right? Can you describe how it looks and where exactly I might see it. Thx Larry | |||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 1038 Registered: 10-2003 Posted From: 71.58.48.5 Rating: N/A |
There is a small cast item that is attached at the connection of the dd3 push rod and slack adjuster connection. Otherwise, there would just be a normal clevis. It can be released with a hammer and reapplied with a small prybar. | |||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1263 Registered: 12-2000 Posted From: 76.66.18.98 Rating: N/A |
Hello John. Have you a picture of this device? Post, or e-mail to me and I'll post it for you in this thread. happy coaching! buswarrior | |||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 1040 Registered: 10-2003 Posted From: 71.58.48.5 Rating: N/A |
Got this from my 4905 service manual:
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| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1270 Registered: 12-2000 Posted From: 76.66.17.12 Rating: N/A |
Thank you John! That release device is not universal, I have a regular clevis on my coach and the parts bus. It will be a very effective mechanism for moving a coach which has the DD3 parking brake unable to release by conventional means, but needs to be used when there is no more air pressure in the park tank, otherwise, when released, the air pressure in the park tank will extend the pushrod further and draw up the slack created by releasing the mechanism. (assuming the brakes are within adjustment, if it is already over stroking, then it won't but you have other problems!) And note, the tabs play an important role to defend against accidental release. Another DD3 feature, being able to release a stuck parking brake with a hammer blow, that spring brakes do not have. With a spring brake, you have to use a caging bolt, which is effective, just takes longer. happy coaching! buswarrior | |||
| Larry Hurd (Lghurd)
Registered Member Username: Lghurd Post Number: 11 Registered: 4-2008 Posted From: 71.96.30.196 Rating: N/A |
BW and John Thats very interesting and good to know. Never heard anyone even mention a way to release these. Most just know the spring brake way. And point taken, BW, on making sure no air at all before you release. Can see how that might create a few more headaches. Havent been able to get back to coach since last week. So when i do I'll let you know what worked (I Hope) Hoping by this weekend, but that was plan last week. Thx for all the info. Larry P.S. Ive got to rebuild at least 1 of the chambers to see how these operate. I never knew that air brakes could function this way. | |||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 1051 Registered: 10-2003 Posted From: 71.58.48.228 Rating: N/A |
If you rebuild them, the rollers have a taper or slight bevel in the middle of each one. This IS NOT WEAR. this helps them to fit the pushrod better. I thought that they were worn and got new rollers that I didn't really need. Could have saved a few small bucks. You need to disassemble and clean and inspect them/ one to determine especially if one of the chamber halves need replaced. They can raise the cost of parts much higher and may cause you to find a used one or two for salvageable cases. Otherwise, once you rebuild them, you shouldn't need to do it again.BTW, Bendix now recommends using antiseize to lube the internal parts in reassembly. | |||
| Tony LEE (T_lee)
Registered Member Username: T_lee Post Number: 25 Registered: 11-2007 Posted From: 90.56.175.15 Rating: N/A |
Isn't air leaking out of the inversion valve a sign of a holed DD3 diaphragm? | |||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 417 Registered: 8-2006 Posted From: 76.91.197.153 Rating: N/A |
Tony, No, the inversion valve pressurizes the parking diaphragm when the parking brakes are applied. If a parking diaphragm is ruptured, the park/emergency application won't be as strong, and the leak will only be heard with the brakes applied. (Unless the leak is in the lock line, which is pressurized when the parking brake is released.) If the service diaphragm is leaking, the other side is vented to atmosphere, and will only be heard when the pedal is applied. Larry is describing the rear relay valve, which has reserevoir pressure on one side of a diaphragm with the brakes released, so a hole there causes a continuous exhaust. We're still guessing what all of his problems turn out to be, and it sounds like he has at least two separate ones... G | |||
| Larry Hurd (Lghurd)
Registered Member Username: Lghurd Post Number: 12 Registered: 4-2008 Posted From: 71.96.30.196 Rating: N/A |
Well I am waiting on a new valve after finally getting that R8 valve out. Had new lines made for every rubber line that connects to that valve. Don't want to go back and try to replace them up in there later. I talked to Bendix tech and he thinks its the diafragm but might be valve. Anyway may be needing to rebuild those DD3. Another mechanic I know said its too bad I don't have Maxis because he could get me some he has and isn't going to use afterall, cheap. He said little or nothing. Which means it depends on what I can barter for them I think. But he can't help on the DD3. I told him I wasn't sure what all would have to be changed. I definantly can see the advantage of DD3 if you have them but if the cost were minimal would you change? Thanks for all the info. It has helped alot to find what I need so far. Larry | |||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 1099 Registered: 10-2003 Posted From: 71.58.48.228 Rating: N/A |
Larry, if you have DD3's, keep them. By the time you get all the plumbing changed around for the maxi's you could just rebuild what you have and move on. Remember, you should only need to rebuild them once. IF you decide to go with Maxi's anyway, make darn sure there is enough room for them AND access to install and turn release bolt. You can probably get Maxi's for less than $50 each almost anywhere. That R-8 is a PITA to remove and repair/ replace, but you'll be glad you did it. Now you know what you have. Keep a log book of the items you repair with the coach. Can be useful down the road, especially as memories fail in later years. | |||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1278 Registered: 12-2000 Posted From: 76.66.19.23 Rating: N/A |
Memories fail in later years? Darn memory is failing now at the genetic half life, never mind later! Write down EVERYTHING you do, think, learn or know about your coach...you'll thank us later. Also, detailed historical note taking can help defend one's liability, if some liar-for-hire takes a run at you for some unintended mishap... happy coaching! buswarrior | |||
| Larry Hurd (Lghurd)
Registered Member Username: Lghurd Post Number: 13 Registered: 4-2008 Posted From: 71.96.30.196 Rating: N/A |
Well I finally got back over to coach. I had the relay valve rebuilt. Turns out its an R6 but couldn't get the one with the right ports. Found a place here in Garland that has rebuilt them for a long time. Charged me $36 and had it to me next morning. I put it back on coach but it was still leaking out the exhaust. I went ahead and pulled off the 2 dd3's along with the inversion valve and all off the hoses. Not sure what I'll do next. Can't really afford to spend to much right now. I figure I'll take the dd3's to rebuild shop. They told me to bring them in and they will test them for me. They want about $250 for each dd3 to be rebuilt. So far I haven't been able to find a rebuild kit that I could buy. So just out of curiousity what would need to be changed in the plumbing to accomadate for spring brakes. | |||
| Gus Causbie (Gusc)
Registered Member Username: Gusc Post Number: 645 Registered: 11-2005 Posted From: 208.54.200.50 Rating: N/A |
Jim, Since your thread has been hijacked I'll try to get back to it. The way you describe it I think you have spring parking brakes. Our 4104s originally came with a mechanical parking brake on the drive shaft just off the transmission. This system had no name that I know of and was common with all heavy trucks in those days. On some there was also a lever or button marked "ICC Brake" or something like that. This brake required air to operate the rear brakes only and was only for emergency stopping since the parking brake sure wouldn't stop it!! It was not to be used for parking because once the air leaked out it didn't operate. Yes, this original system allowed the bus to roll with no air pressure. I'm certain that most 4104 conversions are to spring brakes. I doubt that any 4104 has been converted to DD3 because the spring is so much simpler and, in my opinion, far superior. | |||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 1117 Registered: 10-2003 Posted From: 71.58.48.228 Rating: N/A |
That's not too bad of a price. Be better to get them done when you can afford it instead of changing the chambers to Maxi's and the new work required. Once this is done, you won't have to do it again. | |||
| Larry Hurd (Lghurd)
Registered Member Username: Lghurd Post Number: 14 Registered: 4-2008 Posted From: 71.96.30.196 Rating: N/A |
Yea Thx John He actually quoted me a better price when I took chambers to him. He is going to test each chamber and the inversion valve to see what failed. Then he is going to rebuild all for about $350. He is also gonna try to let me see the inside of the chamber to see how it works. I'll be real honest, I don't feel real good about a brake system that actually can free wheel when air pressure is gone. It makes me feel that even more things have to be right before all works for sure. Obviously I plan to have pads in adjustment at all times and block coach to be safe. I just don't have as much confidence as I once had about air pressure and brakes being set for sure. On the Bendix web site it said the rod actually retracts a little before locking mechanism takes hold. I know if all is right that the system works, but knowing the status of that rod may change some after I leave the coach bothers me quite a bit. I keep thinking about one time in Nashville when there was no where to park but on slope. This was before I saw the roll off possibilities with the dd3's on my coach. There is no way, that at least for a while, that I'll be parking on anything but flat. I could just see headline. "Converted bus makes appearance on Grand Old Opry Stage" Tim I do apologize for hijacking your post. I had read this type of communication before but never used it. Guess its better to start new post for each question but seemed like it would create to many different semi related posts. I know when I saw your question about a coach being able to roll with no air, I figured the info you got would probably answer mine too. I didn't realize that my particular problem wasn't easily explainable just knowing how dd3 and spring brakes worked. I have to say that I have learned so much from this post, its hard to imagine where I would be now without it. Thanks to you Tim and thanks to all who have put in info. Since it's a little late now, I am still going to post what I found to be solution here. Want to just to be sure all who should get info will get it. Thanks again. Larry | |||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1288 Registered: 12-2000 Posted From: 76.68.122.248 Rating: N/A |
Hello Larry. Do not discount a particular brake system just because the example of that system that belongs to you has fallen into disrepair. I could tell you just as many hair raising stories as to how a spring brake system will fail, when ALLOWED to deteriorate into unacceptable conditions. If a busnut regularly inspects the brake system as intended by its manufacturer, is able to recognize when the time has come for prudent parts replacement, and spends the cash, the braking system will perform as expected and as designed. Run it until you notice something wrong from the driver's seat, or don't spend the cash, well, don't expect any of it, regardless of spring or DD3, to be working right by that point. This ain't your father's Oldsmobile... happy coaching! buswarrior | |||
| Jim Wilke (Jim Bob) (Pd41044039)
Registered Member Username: Pd41044039 Post Number: 279 Registered: 2-2001 Posted From: 69.77.155.1 Rating: N/A |
Larry, I think the other poster has it wrong. The parking lock mechanism DOES NOT USE AIR TO STAY LOCKED! It uses air to release. Once your correctly operating DD3 is set in "park" mode, the lock rollers prevent the rod from retracting & releasing. The air to the lock release pushes a piston that releases the rollers once you step on the brake pedal & get a full pressure application. See if you can get/download a cutaway or assembly drawing of the DD3. Once you see how it is put together, you'll understand. It would be a nightmare to change the bus to Maxis and you will open yourself up to massive liability if you get in an accident even if your maxis work properly! The liar for hire will get experts to show how your conversion reduced brake effectiveness even if it's not true. Just think about how a jury of non mechanical housewives & the occasional accountant or shoe salesman will decide about some non engineer who changes the brakes on a 14 ton bus. | |||
| Larry Hurd (Lghurd)
Registered Member Username: Lghurd Post Number: 15 Registered: 4-2008 Posted From: 71.96.30.196 Rating: N/A |
Jim(Jamo) sorry hijacked your post and then called you Tim. Sorry again Jim. Buswarrior Yea I know that is true in my mind, just is gonna take a little while to trust it. Jim Bob Thx for info. I have seen a drawing but I guess I am more of a hands on person. I am very anxious to see the guts of the DD3 when he has it torn apart. Then I can actually see how it works. Still waiting on rebuild of both DD3's and inversion valve....Their sandblasting machine broke down so they are behind a little. I'll post what he ends up finding and what happens after I reinstall them. Thanks for all the great info everyone. Larry | |||
| Larry Hurd (Lghurd)
Registered Member Username: Lghurd Post Number: 16 Registered: 4-2008 Posted From: 71.96.22.128 Rating: N/A |
Brakes working! Sorry it's been so long. Money tight. Just wanted to update solution as best I can tell you. I was not able to see the inside of the dd3's to know exactly what things had all gone wrong in which chambers(dang it). The rebuilder told me there were broken springs, diaphragm failures, and all things inside were very rusted. When I reinstalled the dd3's and inversion valve(also rebuilt) it seemed like the slack adjuster on one side was out of adjustment. I say seemed like because I had to use trial and error to see which way they tightened. (Thx again to JR for digital camera pics idea. It was a long time between take off and put on.) By the way, to adjust my slack adjusters I needed to push in a spring loaded locking device and then turn the adjusting bolt. This was fairly easily done with a socket on the bolt and pushing in pretty firm to be sure I was actually seating the brake pads instead of just tightening against the locking device. After I did it right I could tell by hearing the brake pads actually squeezing against the drums. I didn't see anything on the posts I researched about this so I just wanted to mention if it helps someone. It threw me off for a few minutes. So in the end I think it may have been 2 simultanious problems like I think George had said. It looks like at least one brake chamber had serious problems with diaphrams and springs and maybe one side's brake pads was not in adjustment. It may also be that both brake chambers could have failed. I just wasn't able to find out definativly what all had failed. It does seem strange that both chambers failed but the coach had been sitting a long time. I just want to say a big thanks to George,John,JR, Buswarrior. I had no idea where to start and now I feel very knowledgable about my brake system. Big Kudos to you all and this website. I can now hear the locking rod ingage and release in the dd3's(I have floor out in rear of coach so I can hear while I set and release parking brake) It's a sweet sound to hear. Does it mean your a Busnut when get excited about taking things apart to see how they work and enjoy hearing them work? I guess maybe I am just a Busnut in training. Thanks again Jamo for not getting PO'd for hijacking your post. I see how easy it can happen now. Hope you got your answers. Larry |
DD3 Release Lever