| Author | Message | ||
| Bruce Henderson (Oonrahnjay)
Registered Member Username: Oonrahnjay Post Number: 552 Registered: 8-2004 Posted From: 70.61.105.213  Rating: N/A |
Please have a look at my diagram of my air brake system. (I'm converting to US parts.) (Edited - See post #6) I've been told that I need a Bendix R-14 "Relay Valve" to feed air to the rear cans. Is that true? Bendix's website says that it's only needed for 3-axle single vehicles or vehicles with trailers? I'd appreciate any comments. Thanks, BH NC USA (Message edited by oonrahnjay on June 17, 2010) | ||
| Patrick levenson (Zubzub)
Registered Member Username: Zubzub Post Number: 235 Registered: 5-2007 Posted From: 174.91.225.176  Rating: |
your diagram does not have mains (large air lines) to the cans. My understanding is that the brakes react faster using relays as the control line would otherwise have to large a volume of compressible air in it. In your case the line from the brake pedal needs to control a relay near the cans and the relay applies and exhausts air from the cans. There are dual relays that can be used to control the brakes and the spring brakes, and have an anti-compounding feature (does not allow brakes and spring brakes to be applied at the same time), I chose not to install a dual relay as I wanted to keep thing simple, but some feel it is a must have. I have some experience with this but it is not an area of expertise for me, I suggest you gte more advice, form here and elsewhere. (Message edited by zubzub on June 16, 2010) | ||
| George M. Todd (George_todd)
Registered Member Username: George_todd Post Number: 1037 Registered: 8-2006 Posted From: 99.184.9.29 Rating: N/A |
Bruce, I have a couple of thoughts here. 1. There is no protection valve shown between the 2nd dry reservoir and the auxiliary tank. Most of the later (1969 as in my MC6) have them, which prevents pressure loss in the braking reservoirs when a catastrophic failure occurs in the auxiliary system. 2. Nothing is shown connected to the auxiliary tank, while the air throttle and the horn are connected to the braking reservoirs. These fit my definition of an auxiliary? 3. I would definitely install a relay valve instead of a quick release valve in the rear brakes. This is for increased application speed, and a relay valve also provides the quick release function. 4. You get points in my book for a dual circuit brake valve, and two dry reservoirs! I would install a check valve in the supply line between the two reservoirs, and maybe another in the line right before the 1st dry res, to prevent total instantaneous pressure loss due to a pipe break? G | ||
| George M. Todd (George_todd)
Registered Member Username: George_todd Post Number: 1038 Registered: 8-2006 Posted From: 99.184.9.29 Rating: N/A |
Bruce, This after looking at it some more, and you can see that Zub's comments are right in line with mine, and I like the support. Definitely two check valves, one between the two dry tanks as before, the other between the Wet and the 1st Dry. As the system is drawn now, a leak in either towing connector will drain ALL the reservoirs! I would consider connecting the rear towing connector to the aux. tank? The front towing connector is there to air up the bus while being towed? If so, it needs a check valve also, to prevent air loss from either a breakaway or a hose failure. Next, a SEPERATE fairly large LINE needs to be run from the #1 dry res to the front axle inlet of the dual circuit treadle valve, for the application air for the front brakes, and failure protection as previously mentioned above. The present supply line feeding both sides of the valve should be seperated to only feed the rear side of the treadle valve. The #2 dry res should be fairly close to the rear axle, if possible, and a large line run from it to the relay valve. The present front-to-rear line becomes the control line from the treadle valve to the relay valve. Remember that the rear does 2/3 of the total braking. G | ||
| Bruce Henderson (Oonrahnjay)
Registered Member Username: Oonrahnjay Post Number: 554 Registered: 8-2004 Posted From: 70.61.105.213 Rating: N/A |
OK, thanks. I'll draw up a revised sketch. The "design" of this was done by "somebody who knows what he's doing". I'm totally ignorant of air, which is why I asked your help. A couple of more questions, if I have an R-14 relay valve on the rear axle cans, that means that I don't have to have a quick release valve in addition on that axle, right? (I'll keep the release valve on the front axle circuit.) My "expert" suggested that I have "airup" connectors (towing) front and rear, his thinking is that if you're parked in a narrow spot with your towing connector in an inaccessible location, you'll be glad to have one in the opposite end of the chassis. Finally, the "SEPARATE fairly large LINE" from the aux. tank to the rear relay valve can easily be 3/4" OD tube. Is that large enough? And, the R-14 has two input ports. Is it OK to run a line to one port and plug the other -- or does tank pressure air need to be "Tee-d" to supply air to both inlet ports? The "service" port is self-explanatory, as are the "delivery" ports. Thanks, George and Patrick. I'd appreciate any further comments. | ||
| Bruce Henderson (Oonrahnjay)
Registered Member Username: Oonrahnjay Post Number: 555 Registered: 8-2004 Posted From: 70.61.105.213 Rating: N/A |
A new diagram: http://s45.photobucket.com/albums/f60/oonrahnjay/Bus/?action=view¤t=BrakeDiagramJun1 0.png | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1868 Registered: 12-2000 Posted From: 174.91.143.169  Rating: N/A |
You need to contact Bendix and tell them what you want to do. There are too many problems with your diagram. This is not the stuff for home taught jury-riggers, "experts" or internet bulletin boards. Not to be rude, but this is the most important engineering on your coach, and the lives of other road users are involved. Go ask the more than willing professionals! There are important engineering/pneumatic theories that MUST be applied in your choice of components. And then a few regulations that at least need to be considered as valid direction. Bendix is VERY supportive in the way of giving specific direction as to how to plumb a vehicle for air brakes. Find the right people there to talk to and get written direction from. They'll need some specific measurements for your coach, length of runs, weight, foundation brakes installed... Be sure that they know this is your personal project, not a commercial venture. Every piece of tubing, length of run, every elbow and every component changes the speed and volume of air. They must be assembled in a complimentary fashion. The brakes need to apply together, release together, and have the proportional strength intended during use. There are a number of fail-safe characteristics to modern brake systems that you want to be sure to incorporate, and a few more you might consider, that have not been adopted by regulation as of yet. Just for fun, since you are starting from scratch, consider a Bendix AD-IS air drier to design around: 4 built-in combination check valve/pressure protection valves, it provides a higher degree of safety/redundancy than traditional check valves, and allows the compressor to continue partially airing the sound parts of the air system while the failed circuit is leaking. happy coaching! buswarrior | ||
| George M. Todd (George_todd)
Registered Member Username: George_todd Post Number: 1039 Registered: 8-2006 Posted From: 99.184.9.29 Rating: N/A |
Bruce, BW is one of the more qualified air brake people here. Aside from that, the new diagram looks better, we just didn't communicate 100%. The rear relay valve needs to be fed from the #2 Dry Res, not the Aux. Also, the parking brake should be fed from the #1 Dry Res. 3/4 is more than sufficient, I doubt you will find more than 1/2 on most buses. G | ||
| Bruce Henderson (Oonrahnjay)
Registered Member Username: Oonrahnjay Post Number: 557 Registered: 8-2004 Posted From: 70.61.105.213 Rating: N/A |
Thanks, BW. I didn't know that such help was available from Bendix. That's what I'll do. Thanks also for the tip on the AD-IS air drier -- it sounds as if that will solve lots of my problems. And thanks, George, too. | ||
| Jim Wilke (Jim Bob) (Pd41044039)
Registered Member Username: Pd41044039 Post Number: 504 Registered: 2-2001 Posted From: 184.0.3.170 Rating: N/A |
And Bruce, let me toss in my $.02 here. I think you'll find that one air up fitting is enough. I would think you might have a 50' air hose on board to air up tires, etc. Use that to go from one end to the other IF you ever need it. I feel that one in the front is more practical as that's where a towtruck would connect if towing your bus rear wheels down. That way he wouldn't have to stretch a hose to the back & figure out how to keep it off the road. If you are not moving, but just airing a dead bus from the rear, it doesn't matter if the hose is on the ground, eh? | ||
| George M. Todd (George_todd)
Registered Member Username: George_todd Post Number: 1040 Registered: 8-2006 Posted From: 99.184.9.29 Rating: N/A |
Bruce, I'm home from work, and have had some time to look at the second diagram, so here's some more suggestions. 1. Air more or less flows in one direction thru brake systems, except between the cans and the treadle valve, etc. With check valves, and a protection valve, we try to prevent a failure from becoming a catastrophe. So, the towing connections should be teed into the compressor output line before the check valve protecting the wet tank. If connected as drawn in the second drawing, the check valves I suggested will prevent the whole system from airing up from the towing connections. A protection valve should be put in the line between the #2 Dry Res and the Aux Res, instead of the check valve shown. Protection valves don't open until about 80 psi, which pressurizes the brake reservoirs before allowing air into the auxiliaries. It will also close in the event of a big leak in the auxiliaries, keeping 80 psi in the brake reservoirs. The rear relay valve still needs to be fed by the #2 Dry Res, and the parking brake knob should be fed from the #1 Dry Res, so it won't trip from low auxiliary pressure, and will trip from low brake res pressure. Most of the parking brake systems use a relay valve for much quicker applications and releases. Supply it with air from the #2 Res. G | ||
| Bruce Henderson (Oonrahnjay)
Registered Member Username: Oonrahnjay Post Number: 559 Registered: 8-2004 Posted From: 12.52.187.202 Rating: N/A |
Thanks, George. As BW suggested, I have already contacted Bendix tech line; I'm assuming that I'll get a contact for a specific "expert". As part of providing info to the expert, I'll send a copy of the layout of my bus etc. So, suggestions now will go on the chart for the expert to consider. I'm away for the weekend but I'll let you know what I hear next week. And thanks for the clear thought, Jim Bob -- the few number of connections, pipes, etc., the few problems, I suppose. | ||
| Bruce Henderson (Oonrahnjay)
Registered Member Username: Oonrahnjay Post Number: 560 Registered: 8-2004 Posted From: 64.147.210.162 Rating: N/A |
Further revision, (incorporating suggestions so far); thanks for suggestions: http://s45.photobucket.com/albums/f60/oonrahnjay/Bus/?action=view¤t=BDiagJun10Ann.jp g | ||
| Patrick levenson (Zubzub)
Registered Member Username: Zubzub Post Number: 237 Registered: 5-2007 Posted From: 174.91.225.176 Rating: N/A |
Getting closer. 2 things I notice. Sprink brake (parking brake) also needs a relay. the 1/4" is just a control line, you need a realy back there with it's own 1/2"? supply just like the brake relay. in fact the p brake set up works kind of exactly like the service brake...but opposite. If you kept the cuureent set up it would take forever to set and un-set your P brake...BTW I mentioned above there is a single relay that will control both the service brake and the P brake. requires only one supply line and you just hook up the 2 control lines from the cockpit to it...simpler instal and since you are starting from scratch less expensive than 2 relays. The other item is the air throttle ....this I know less about but is the air throttle usually run of the aux tank?....my instinct would be to run it off the mains.....but what do I know. Speaking of which... .WHAT DO I KNOW? ........ ALMOST NOTHING! ...... Please keep this in mind and as you get closer to a working model make sure you get a pro of some sort to vet your design. Like BW said, you don't want any armchair "engineers" working it out for you, and I don't want to be responsible for your braking system. You're getting closer .though. | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1870 Registered: 12-2000 Posted From: 174.91.145.77 Rating: |
Treating this as an academic exercise... Both service tanks need to be plumbed in parallel, not in series. Take those filters out of the lines leading to the brake pedal. Effect of their becoming plugged? Alcohol will ruin your air drier desiccant. If you want one, put an alcohol injector after the air drier. The "blow off valve"... this is built into the bottom of the air drier, it is how it dries itself between cycles. Or do you mean a discharge muffler, as MCI calls it, some call it the ping tank. it catches a bunch of water/goop before it bothers getting to the air drier. Air gauges, you want plumbed to your tank circuits. Depending on where that one to the compressor line is, it will read zero when the compressor is cut out. Need a brake light switch in both sides of the service system. And some consideration to the parking circuit. If you are going to plumb it, and you will, with an SR-1 (or equivalent) spring brake relay valve. If plumbed correctly, it will modulate the springs on the rear brakes under a rear service failure, automatically by way of the brake pedal. You'll never know it saved your bacon, you'll just have the low air warning blaring away. Low air warning - into both service circuits, they don't have to be at the low pressures of the minimum regulation. When do you want to know you have low air? If it runs normally above 90 lbs, why not have it alarm at 80? 60 pounds is a long way from normal, and the parking springs are already starting to drag... and alarm the auxiliary too. What fun we be havin' happy coaching! buswarrior | ||
| George M. Todd (George_todd)
Registered Member Username: George_todd Post Number: 1045 Registered: 8-2006 Posted From: 99.184.9.29 Rating: N/A |
Zub, Please look at the last paragraph of my post of 6/17, 1142pm. Also, I run nothing off the brake reservoirs except the brakes. It can be argued that revving the engine sooner to build air pressure faster would be accomplished by connecting the air throttle to a brake reservoir, but I suggested it the way I did, because of the sentence immediately before, nothing off the brake reservoirs except the brakes. That does mean the shifter servo has to move to the auxiliary line. Bruce, From the academic point, I suggested the reservoirs be in series, with a check inbetween, to prevent a total pressure loss in both from a line failure. They could be fed in parallel, with a check on each, which would accomplish the same result. Apparently I got what I asked for, but the check valve on the line between the dist tank and the unloader, has to move to the short line between the dist tank and the 1st service tank, for two reasons. 1. The unloader won't work right when it only sees a check valve instead of a tank. 2. We're not protecting the 1st service tank from a failure in the dist tank or charging circut, without a check between the two. This is also BW's "...Depending on where that one to the compressor line is...it will read zero when the compressor is cut out." The only other thing to mention, is that the spring brakes won't begin to drag, as the parking knob will pop up from low air pressure and cause a full application first. (See BW's comment about the SR-1 or equivalent spring brake relay valve.) The parking brake light switch in my MC6 is powered thru the master, so the brake lights don't stay on when parked with the engine off, and run the battery down. The others of course, are off when the pedal is released. The parking brake switch is N/C, closed with no pressure. Move these two, and we're there! G | ||
| Bruce Henderson (Oonrahnjay)
Registered Member Username: Oonrahnjay Post Number: 561 Registered: 8-2004 Posted From: 64.147.210.162 Rating: N/A |
Thank you all for your comments. I'm learning a lot here and I'll be much better prepared to provide info to the Bendix tech person. And it *is* an academic exercise because all the stuff here will probably be changed by the use of the AD-IS air dryer, but the discussions are very helpful. I'll redraw the diagram for the tanks to be in parallel and make a note to communicate this with the Bendix person, The alcohol injector is as stock on the vehicle (British 1970's technology). It's there but I never considered using it, although I guess if I were in v. cold weather, I'd be tempted to. The position of this (if it can be used) or some other injecton system will depend on the AD-IS dryer. The issue for the stainers; I'm pretty sure that I can pull the guts in 3 minutes apiece. The "blow off" valve is a safety valve, put into the line out of the compressor. It's set for 150 PSI and it's there purely as an emergency over-pressure (if the compressor were to over-compress??) relief valve. Another item that will have to be matched to the AD-IS. The line to feed the air gauges will be easy to move. They have the pressure switches for the low-air horn right with them. I think that this setup is a part of the design of the stock system. The book says that there is no "governor" on the compressor; the high pressure is modulated by the unloader valve; when the tanks are full, additional air from the compressor is dumped to atmosphere. It's a strange system and I'm a bit afraid that there may be problems matching it to the AD-IS but there should be some way. (It may be why the book suggests rebuilding the compressor every 50K miles or 1 year.) It will be no problem to add an additional brake light system in the front brake line. And I don't mean to ask too much, but what go you mean by "consideration for the park circuit"? (I get the impression that the brake light should come on when the emergency function of the spring brakes is triggered. Again, easy to incorporate.) I'll be sure to ask the Bendix person about the SR--1 relay valve. It has been mentioned a couple of times that a relay is needed in the parking/emerg brake system and I suppose that this is it. I'll check the specs on the low air sensors in the system. BW's comment on the setting makes perfect sense and that's how I'll ask the Bendix pro for info. Also, it will be easy to add further sensors. Thanks again to everyone for the learning assistance. BH NC USA | ||
| Patrick levenson (Zubzub)
Registered Member Username: Zubzub Post Number: 238 Registered: 5-2007 Posted From: 70.51.28.192 Rating: N/A |
I like this site http://www.anythingtruck.com/commercial/airb_bendix_valves.html because it explains relays and sells them inexpensively. this is a sr-1 http://www.anythingtruck.com/Merchant2/merchant.mv?Screen=PROD&Category_Code=HTP-AIRB&Prod uct_Code=061-286364X | ||
| Ralph Peters (Ralph7)
Registered Member Username: Ralph7 Post Number: 124 Registered: 3-2004 Posted From: 75.225.33.192 Rating: N/A |
IF you go to a medium duty truck with air brakes, or a dump truck you will see how it works. You need a RE-6 or a re-8 for the rear axle. Cause re (relay emergency) monitors air pressure and if air pressure drops below 60psi your spring brakes are applied. Buses with DD3 use R-6 or R-8. When looking at air brakes do not use a tractor or a truck that tows a air brake trailer. The diagragms to look at again are for 2-3 axle trucks. Did your unit have air brakes before and was it the early type that without spring brake for emergency brakeing? Some early air brake vehicles had a hand brake for parking. On spring brake cans air pressure is used to retract (compress) the spring,when you push the yellow button. The reason for the relay valve is to get volume to the rear wheels, even with a air tank near them, QR valves ( quick release) is to release applied air to get the shoes away from the drums. Front brakes do not normally use relay valves, but must have a Qr valve. After looking at a diagraham, are you adding the air throttle to a spring system that is in place or also adding spring brakes? As for r-14 no you need RE-6 or 8 for to spring brakes to work. Both R-# and RE-# have 4 ports to service (apply) brakes, you plug 2 ports (holes) if you have a single rear axle and use all 4 ports if you have a second or tag or boggie axle. IF this clear as mud, let me know. | ||
| George M. Todd (George_todd)
Registered Member Username: George_todd Post Number: 1046 Registered: 8-2006 Posted From: 99.184.9.29 Rating: N/A |
Ralph, Its very clear, and good advice. The only problem is that Bruce's bus is British, which changes almost everything. The compressor doesn't unload like "ours" do, they just let it keep on loading, and waste the air (and the energy.) As my mother was born in Scotland, I know why the British drink warm beer, do you? G | ||
| Ralph Peters (Ralph7)
Registered Member Username: Ralph7 Post Number: 125 Registered: 3-2004 Posted From: 75.225.161.96 Rating: N/A |
George we kept to milk in the spring water, AND the British do things & thinks a little different. Can he change compressors? But you need a 150psi popoff in line from compressor and before any check/oneway valve, some install it in the head of the compressor. | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1874 Registered: 12-2000 Posted From: 174.89.174.64 Rating: N/A |
George, re your comment: "The only other thing to mention, is that the spring brakes won't begin to drag, as the parking knob will pop up from low air pressure and cause a full application first. (See BW's comment about the SR-1 or equivalent spring brake relay valve.)" The springs WILL begin dragging as the pressure to them drops through the 60 pound range. The parking control valve won't pop until the pressure drops to the 40 pound range or below, depending on the strength of the return spring in the valve. The two events, spring chambers starting to squeeze, and the parking control valve popping, are dependent on the strength of each of those springs in relation to the air pressure applied to them, and during a typical steady drop in pressure, unrelated to each other. You'll already be stopped before the knob pops. Remember, the KNOBS that teach this stuff taught all that brake pumping and other crap while sitting still. Can't see that the springs already came on when you're sitting still in the driver's seat madly pumping on the brake pedal. As I've said before, everything one thinks was learned from a driver trainer must be held suspect, there are precious few requirements, training, or certification, to be a driver trainer, and the errors, myths and out and out fabrications just keep getting repeated, generation after generation. This spring dragging is why some of the old timers were VERY upset with the beginning of FMVSS 121 in 1975, the springs can drag just above the low air warning, risking a fire, and there's no indication to the driver. Especially in the trailer, where, with the small size of the supply line, and running down the road at speed, the tractor air supply might stay above 90 lbs, and a drain valve could be snapped off on a tank in the trailer, with the springs dragging... with a tire fire to soon follow. For our coaches, the low air warnings should really be way up at 80 pounds, or higher, on the newest 130 pound cut-out systems. But try to get this nuance through the unknowing and largely uninterested bureaucracy.... happy coaching! buswarrior | ||
| George M. Todd (George_todd)
Registered Member Username: George_todd Post Number: 1051 Registered: 8-2006 Posted From: 99.184.9.29 Rating: N/A |
BW, I agree with you fully that when reservoir pressure falls below the point where it keeps the springs retracted, they will begin to apply. I also agree completely that the low air warning should operate at a minimum of 80 psi, because when brake reservoir pressure drops to 80, something's wrong! If it does warn at 80, we have no issue. If the emergency application is set for a minimum of 70 psi, we don't have an issue either! The scenario you use of a leak on a trailer causing dragging SHOULD be prevented by the trailer protection valve, which should trip in that exact situation of greatly increased flow. (Note the advice to Bruce to use a 3 axle vehicle diagram, instead of a tractor.) Living at the 1000 foot level of Interstate 80, and driving over the 7200 foot summit to get to work, I regularly see trucks with brake (and cargo) fires from too fast a descent with a heavy load, and none on I-5 on the flatlands between Bakersfield and Redding. G | ||
| Bruce Henderson (Oonrahnjay)
Registered Member Username: Oonrahnjay Post Number: 563 Registered: 8-2004 Posted From: 70.61.105.213 Rating: N/A |
OK, if anyone is still reading this ... I've posted a revised diagram: http://s45.photobucket.com/albums/f60/oonrahnjay/Bus/?action=view¤t=BDiagJun22Col.jp g Red = Compressor and charging system to distribution tank; Green = Service tank 1 and front brake circuit; Blue = Service tank 2 and rear brake circuit; Brown = Auxiliary tank and accessories. Two questions, please. Is it necessary to supply tank air to the SR-1 valve, and if so, is it OK to T off the supply to the R-14 as I've shown here? Also, where would the brake light sensor for the emergency function be located and how would it work ("Open with pressure/Closed with no pressure")? Many thanks for your continued assistance. (Still no reply from Bendix - if nothing by mid-day, I'll give them a call.) | ||
| Bruce Henderson (Oonrahnjay)
Registered Member Username: Oonrahnjay Post Number: 565 Registered: 8-2004 Posted From: 70.61.105.213 Rating: N/A |
Technical assistance from Bendix: "Please visit our Contacts page: http://www.bendix.com/en-us/contacts/Pages/Home.aspx and choose a dealer or distributor in your area. They will be able to give you price and availability details." Oh, well ... | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1877 Registered: 12-2000 Posted From: 174.91.146.121 Rating: N/A |
Bruce, the parking circuit should be fed by way of a two way check valve from both service circuits. The springs must be held released by whichever part of the service system is still intact, under a failure. Brake light indication for the parking circuit would be plumbed in to the spring circuit, so that no pressure to the springs would put the brake lights on. Call that first tank the "supply tank" or the "wet tank" so more folks can get an idea. Those filters are still there in the brake lines, dump them. The alcohol system (methyl hydrate is the fancy name) must not be plumbed ahead of the air drier, it will turn the desiccant into a contaminating mud that gets sucked deeper into the system. George, the tractor protection valve won't close, as the small size of the line to the trailer plumbing either in the tractor or in the trailer, or both, prevents the pressure from dropping far enough. The compressor keeps up with the leak. That is the big devil in the details. The theory doesn't match with reality. In practical terms, the trailer is more likely to be plumbed spring brake priority, (which a lot of people don't know, the first breath of air to the trailer releases the springs, and then fills the tanks, not the other way around) in which case the springs are staying released, but there is no air for the service brakes in the trailer. Unfortunately, the only way to get braking action on the trailer under this condition is by way of the driver pulling the trailer supply control, or the parking brake control. And how many drivers over the years have been told not to activate the parking controls while underway.... We had that exact accident here a number of years back with a 6 axle garbage hauler. Drain valve knocked off earlier by road debris, wouldn't slow on brake pedal application, killed a pedestrian on the far corner, when the compromised unit punted an auto across the intersection on a downhill ramp off the highway. The sizing of certain lines in a tractor trailer unit defeats the basic theories that we've been taught as to the "safety" of these systems. And spring brake priority is a sin brought to us by the wants of industry to swap trailers off the docks instantly, not having to wait for the trailer to air up, and the regulators have allowed this to happen. oh well... happy coaching! buswarrior | ||
| Bruce Henderson (Oonrahnjay)
Registered Member Username: Oonrahnjay Post Number: 566 Registered: 8-2004 Posted From: 70.61.105.213 Rating: N/A |
Thanks for the info, BW. I have a little item to be clarified in my mind, you said: "the parking circuit should be fed by way of a two way check valve from both service circuits." Do you mean that the parking brake switch should be fed from both brake tanks or that both tanks should feed the large pipe going to the rear axle? I've made the amendments to the diagram to reflect the previous items (strainers, methyl) that I had meant to remove but missed. I also added the emergency/park brake light switch which I had had on my list but forgot. (Also, I have established contact with a live person at Bendix tech center and we'll find out how that develops. Unfortunately, he tells me that the AD-IS is specific for each OEM vehicle and is not available for aftermarket.) | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1879 Registered: 12-2000 Posted From: 174.89.174.36 Rating: N/A |
both tanks should feed the parking brake, via a two way check valve. If one or the other tank circuit has a failure, the good one will keep the parking brake released. Too bad about the AD-IS. I guess they don't want it in the hands of the unknowing... happy coaching! buswarrior | ||
| Bruce Henderson (Oonrahnjay)
Registered Member Username: Oonrahnjay Post Number: 567 Registered: 8-2004 Posted From: 70.61.105.213 Rating: N/A |
Apologies that this has gone on so long. Here is latest: http://s45.photobucket.com/albums/f60/oonrahnjay/Bus/?action=view¤t=BDiagJun24ColN-1.jpg I've made the amendments; I showed the check valves onto the parking brake switch supply as two separate valves but it means one double valve. I've asked the Bendix guy if it's appropriate to use the DC-1 check valve there (it looks to me like that's the right one). Many, many thanks for all the help. (Message edited by oonrahnjay on June 23, 2010) |
