| Author |
Message |
Jim Shepherd (Rv_safetyman)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, February 22, 2006 - 8:13 pm: | |
I hate to start yet another thread on release problems on brake systems. I have gone through many of the previous threads and can’t find an answer to my problem.
As background, I had previously replaced the SR1 valve, and I just replaced the spring brake cans (preventative maintenance).
I have had this problem since I bought the bus. Sometimes the brakes release with only one application of the service brakes. Other times it may take 20 applications (with all of the associated waiting for the pressure to build up -arggggg).
The problem seems to have gotten worse recently as I began testing the engine/transmission conversion.
It is cold in CO right now, but today, it was into the 50s and I still had the problem.
I have tried to work my way thought the very detailed description of the Eagle brake system in the repair manual, but I keep getting lost in the various circuits, or end up falling asleep.
So, I bring this subject up again to see if I get any new ideas.
I am wondering if the push-pull control valve needs to be replaced, but I have never heard of a problem with them. If it does need to be replaced, is it unique to the "service brake release" system?
In one of the previous threads, someone mentioned fanning the brakes to reduce the system pressure before pulling the control valve. I have not tried that, but a properly working system should not have to endure that procedure.
BTW, Eagles have spring brakes and not DD3 brakes.
This is very frustrating. I have been parking the bus in gear (10 speed AutoShift mechanical transmission) and then chocking the wheels. Not the best work-around, but it does get me by.
Thanks for any new ideas
Jim Shepherd
Evergreen, CO
’85 Eagle 10
http://rvsafetysystems.com Toll Free: 1**888**349**0704
Bus Project details: http://www.rvsafetysystems.com/busproject.htm (updated 2/9/06) |
Ed Jewett (Kristinsgrandpa)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, February 22, 2006 - 9:32 pm: | |
I dont know much about spring brakes but, could you put a "T" in the line, with a gauge, at the brake chamber and see if it is getting enough air PSI. If so maybe check the linkage for adjustment.
Maybe I'm way off couse but that is what came to my mind when I read your post.
I'm sure someone will set me straight if I'm not thinking straight.(They always do, and I appreciate it.)
Ed |
Tim Jones (Torquester)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, February 22, 2006 - 11:38 pm: | |
Hi Jim,
A normal spring brake set up only requires that pressure be added to the spring chamber to release. This seems to be normally achieved with the PP1 (parking brake controll valve on the dash) and a QR1 valve (a quick release valve by the rear axle). Some applications used a relay valve instead of the quick release (QR8 maybe ???) No application of the service brake is needed in either application.
IIRC your bus is a transit which may have used special logic requiring additional steps. If this is the case I prolly can't help much.
If you have a "standard" type application on your bus, and are still having release problems, I would suspect any of the following:
1. Binding in the foundation system (could be anything from dry s-cams or seized rollers to messed up auto-slacks.
2.Weak , damaged or missing foundation springs.
3. A combination of the above which compounds itself by application of the park brake while the bus is parked on an incline.
I'm just throwing some thing out there, as usual please feel free to call me.
hth, Tq |
Jim Shepherd (Rv_safetyman)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, February 23, 2006 - 12:03 am: | |
Hi Tim.
I am confused. My bus is an '85 Eagle 10 and requires the application of the service brake to release the parking brake. Is that not the case on your Eagle? If not, it must have been converted to a conventional truck system.
I would like to convert mine to the simple system, but don't know what all needs to be changed. If someone has done the conversion to get rid of the service pedal requirement, I would love the get a list of the parts involved.
In terms of binding, I just replaced the brakes on the drive axle and checked all of the parts you mentioned. Everything seemed to be in good condition. I lubed the S cam shaft and the automatic adjusters. I tested the S cam operation with the slack adjusters disconnected from the cans and everthing seemed to move very easily.
I aired up the system with shop air and had the better half operate the system while I observed it from underneath. When she was working the system, it worked great except for one time and then it only took a second service brake apppliction. Everything moved smoothly with no obvious binding. The valve sounded normal to me, but I don't know what I should be hearing. She did complain that the push-pull valve was very hard to operate with the pushing being the hardest.
Jim |
Tom Caffrey (Pvcces)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, February 23, 2006 - 1:21 am: | |
Jim, if you don't have something very different than an ordinary spring brake setup, I would be looking hard at the parking brake valve that your wife says is hard to operate.
All a regular spring brake requires to get rolling is around 45-60 psi applied to the rear chamber to overcome the parking spring.
If you actually have a system that requires a service brake application to release, I am not familiar with that design.
Is it possible that you have a mix and match problem? Could it be that your manual has instructions for DD3 while your coach has been partially or fully converted to a spring brake setup?
I would expect the manual to be clear on that if they didn't want mechanics getting into trouble when servicing these units.
For what it's worth.
Tom Caffrey PD4106-2576
Suncatcher
Ketchikan, Alaska |
Ken Turner (Pipesusmc)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, February 23, 2006 - 1:49 am: | |
I with you TOM. He more than likely has the DD3 system. Or somebody added spring brake cans not knowing the that the the TWO systems are not compatible........If that is the case he would have to put DD3 cans back on the bus.
DD3 cans have 3 air lines (Or should) --------Spring brakes have 2 air lines
BTW ONE new (rebuilt?) DD3 can on ebay for $450!!!!!!! No bids last time I looked
Question..Did EAGLE bus FACTORY ever switch to the Spring brake system. or was it DD3 to the end? |
Richard Bowyer (Drivingmisslazy)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, February 23, 2006 - 10:19 am: | |
My 80 Eagle 10 only required pushing or pulling the knob to set or release the brakes. No application of the service brake required.
I suspect someone has installed the incorrect brake can or something like that. I can not believe that Eagle would have changed their brake design between 1980 and 1985.
Richard |
Jim Shepherd (Rv_safetyman)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, February 23, 2006 - 10:49 am: | |
Hi folks. Thanks for the great replies so far. Please keep them coming.
My brake system is clearly a spring brake system –not DD3. The manual shows only two lines and shows a spring brake in the repair section. The dash states that you must apply full service brake at 100 PSI in order to release the spring brake.
I checked the manual, and the park control valve is a PP1 which turns out to be a common valve according to the Bendix manual. I will get one tomorrow and see if that helps.
Jim |
Ken Turner (Pipesusmc)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, February 23, 2006 - 11:39 am: | |
"The dash states that you must apply full service brake at 100 PSI in order to release the spring brake."
Jim... I am not a brake expert! but that statement above is contradictory for the operation of the spring brake release.
There is an ANTI COMPOUDING valve on spring brakes to prevent sending air pressure (via the foot peddle ) to the already locked up brakes, which would double the force on the brake actuators.
The first thing I did on my 05 eagle was to COMPLEATLY rip out the DD3 system and install the spring brakes with all new parts, I spent around $800 just for the brass fittings !!
my reason is in the snip from my web page below
There is pic of my german shepperd not included in the snip (Just to make sense to the statement below)
"Nik Nik Turner certified Bus Mutt, he's on his way to the D O L to get his C D L he had stepped on the DD3 brake button while we were in a restaurant and as result had his first driving test in Oregon. I had to jump in the rolling bus and slapped my hand on the foot brake just as it rear ended a car and almost shoved everything into the front of the restaurant" |
Stan
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, February 23, 2006 - 12:28 pm: | |
Everyone has assumed that you have a standard spring brake or DD-3 brake and given excellent advice. Apparently you have something that no one on the board, so far, has ever heard off. Is it possible to scan the air diagram so that we can see it? |
Richard Bowyer (Drivingmisslazy)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, February 23, 2006 - 1:02 pm: | |
Jim, maybe you need to check the title on that manual! LOL
Richard |
Alan Baker
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, February 23, 2006 - 3:20 pm: | |
I have an 84 Eagle model 10 with exactly the same brake set up as you describe Jim.
On occation I have experienced the same problem when moving the coach for the 1st time that day. I always figgure I have hit the release button and stepped on the brake too soon. My solution is to wait until the bus is fully aired up at which time the brakes always release.
I know this is not a solution to your problem, I just wanted you and others to know that your brake system is as it was when it left the factory.
Jim, don't forget to send me some pictures for next years Bussin'
Richard, as I understand it some of the 1980 model 10 Eagles were still mostly 05's. |
Stan
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, February 23, 2006 - 3:51 pm: | |
Alan: Can you enlighten us any on how this system is put together? |
Tim Jones (Torquester)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, February 23, 2006 - 5:00 pm: | |
Jim,
I did a little research today and I think that you might have an inversion valve on your coach. I think I might have one too after I saw a picture of one. Mine is obviously not working but that is another story. I think that mine might be a TR-2. You might have a TR-3 because your coach is newer.
I think that we may have had DD3 systems at some point, or Bus & Car Mfg. (in my case) may have plumbed these valves in a a safety precaution. I don't know....take a look at this and see what you think:
http://www.bendix.com/downloads/service_data_sheet/034650.pdf
hth, Tq |
Donald Lee Schwanke (Dontx)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, February 23, 2006 - 5:01 pm: | |
You know, over the years the "stomp the brake pedal non DD3" type subject has came up before, so I tend to believe what Jim is trying to tell us. Like the rest of you, I cannot fathom such a spring brake system though. Please give us more information Jim.
I have also heard that the brake pedal action was for buses, so that in case some passenger happened to play with the brake knob, the bus would not roll off with its passenger load. Amazing how those stories get started sometimes. |
Tim Jones (Torquester)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, February 23, 2006 - 5:51 pm: | |
Jim,
More information about inversion valves not explained in that document:
Inversion valves are air operated control valves, and unlike most
control valves are normally open, ie; without control pressure the
supply is common to the delivery. The inversion valve is closed by
using air pressure from another source and is primarily used in
emergency or parking brake systems which operate with air from
an isolated reservoir. The valve is also used in interlocking and
sequencing applications, where the operation of components must
take place in specific sequence.
The TR-2 was designed primarily for use in early DD-3 Safety
Actuator installations. It is equipped with a threaded body and nut
for mounting.
The TR-3 is also used extensively in DD-3 systems but is also
used in interlocking applications. Two mounting holes are provided
for mounting.
I'm thinking that they sequenced the pressurization of the spring chamber as a safety measure. If this is true, your problem could be this inversion valve or lack of sufficient differential pressure to cycle the valve.Was your system up to full pressure when this problem occured? It could also be that they are controlling a relay valve with this inversion valve and that the relay valve is sticking.
I guess we might both need to crawl under our coaches and make ourselves some schematics to figure this out. <sigh>
Later, Tq |
Tim Jones (Torquester)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, February 23, 2006 - 5:55 pm: | |
If anybody wants air system schematics. They can be found here:
http://bendix.com/downloads/quick_ref_cat/TypicalAirSystems.pdf |
Donald Lee Schwanke (Dontx)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, February 23, 2006 - 6:51 pm: | |
I think you are on the right track Tim. Sure agrees with basics of all the stories. |
Jim Shepherd (Rv_safetyman)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, February 23, 2006 - 11:36 pm: | |
I really appreciate you folks hanging in there with me.
Tim, the system does not have a TR-2 or TR-3. What it does have is a combination of an SV-1 (synchro valve) and DC-4 double check valve. The unique plumbing seems to be the source of needing to apply the service brake to release the parking brakes.
I have been studying the Bendix book and it looks like removing the SV-1 valve from the system will make it a standard truck system.
I have removed the two components (located in the compartment below the electrical panel next to the driver). The DC-4 valve seems to be special for this application if I understand the Bendix schematic correctly.
When I go to pick up the PP1 (push-pull control valve) I will see if I can find a standard DC-4 valve.
Short of that, I will leave both the SV-1 and DC-4 out of the system and be very careful not to set the spring brake when the service brakes are applied.
I will keep you all posted.
Jim |
Pat (Proudeagle10)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, February 24, 2006 - 10:45 am: | |
Jim I had the same problem for months. I push, I pull, I step on the brake, I took every thing lose, put it together again, and no joy. Got tired and walked away from it for days. Went back not knowing what I was going to do. I stated her up and had all the same problems. For some reason I decided to pull on the brake paddle and Wa'la it released. The problem was the paddle was not releaseing all the way at times. Oiled it up, worked a few times by hand and work good so far.By the way I have an 80 Eagle 10. |
Jim Shepherd (Rv_safetyman)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, February 25, 2006 - 10:30 am: | |
Just a quick update. I replaced the push-pull parking brake and tried to eliminate the SV1 and DC-4 valves to get me to a simple truck parking brake system. It turned out to be more complicated than that. I had to re-install the valves and will have to live with that for a while since I am frantically trying to get the bus ready for its maiden voyage to CA next weekend. When I get back, I will probably do some tracing of the circuits and see what would be required to get rid of the service brake application requirement.
I did do a quick test and the brake released just fine a couple of times. However, it has done that before only to go back to its wicked ways.
Pat, funny you should bring up the pedal sticking problem. When I drove the bus this past week, I had the lab top hooked up for use of the Delorme and Silverleaf programs. When I pulled up to the shop, the brakes stuck again. I saw that the laptop was attached to our Wi-Fi network and I sat there reading all of the old threads, trying to figure out what was going on (as I let the system re-build pressure – many times). One of the threads mentioned the sticking service brake pedal problem. I reached down and tried it, but it did not seem to be stuck and did not make a difference. However, I was very frustrated at that point and I am not sure that anything was making any sense. I will lube the pedal and try it again if I run into more problems.
Again, thanks to all the great folks on this board who have helped me dig deeper into this problem.
Jim |
Buswarrior (Buswarrior)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 28, 2006 - 9:18 pm: | |
Hello Jim.
From your descriptions, I think I am getting a handle on what you've got.
As noted, it sounds like a system designed to prevent the accidental rolling away of the bus, if the parking control knob is pushed in through some misadventure.
Happened to my father back in the 70's at the Peace Bridge Customs Inspection. A passenger's briefcase went down the gap between the driver's modesty panel and the seat, pushing in the brake control. Luckily, dad was just outside and was able to stop it without incident in a few feet.
Anyway, I suspect that the SV1 valve will have a line to the control port from the service brakes, a line to the supply port from the push-pull valve, and a line that will head to the rest of the parking system, "back there" attached to the delivery. The exhaust port will be open to atmosphere.
I'm further guessing that your DC4 will have three ports in play, one input each from the primary and secondary, and one output heading to the push pull valve.
I would suspect that the internals of the SV1 have expired, making their functioning erratic.
If you can get a new SV1, you will retain a handy safety feature, especially if there are kids around. Saves remembering to pump the brakes down to make it safe from a roll away.
If you want to try a quick bypass, from the SV1, tie the supply and delivery lines together and see what happens. If it works, cap off the service brake control line to stop the air leak on service brake application and away you go.
Or something like that?
Let us know how you make out Jim!
happy coaching!
buswarrior |
Jim Shepherd (Rv_safetyman)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 28, 2006 - 11:21 pm: | |
Ewen, I think you have it just about spot on. However, the DC4 and the SV1 are tied together by both a tubing connection and a common port. As a result, the Eagle DC4 really has four ports as opposed to the typical DC4 check valve. It sure looks like the combination SV1/DC4 combination is somewhat special for the Eagle. I can mail you a copy of the portion of the repair manual that deals with this valve combination if you wish. I may also try to post it on my website if I have time when I am on the road. If you want the paper version, drop me your snail mail off line.
I tried to remove both from the system and the system did not react well. I reinstalled everything and replaced the PP1 (parking push/pull valve) with a new one. So far, the brakes have released several times in the shop with shop air. We will see what happens when it gets into the real world. I will be doing my final check out drive Thursday.
Since I am out of time to work on the system before I leave, plus the fact that I have a work around (shut off engine in gear and chock the wheels), I will postpone further effort on the system until I return (mid-April). At that time, I will probably tear down both valves and replace the “O” rings and do a thorough inspection. I will also play with converting the system to a “simple truck system”.
BTW, for those still reading this thread, the system is still functional and safe. The parking brakes can be applied without problems. The only problem is releasing the parking brakes.
Jim |
James Wilke
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 01, 2006 - 2:58 pm: | |
I have a 4104 converted to truck type spring brakes, a 4905 with DD3s and an Eagle with (I guess) the DC4 that you have to make an application to release.
I would absolutely not remove the application / release feature.
I was outside the 4104 when our dog stepped on the yellow button (installed in the switch panel under the driver's left side window). The parking brakes released & this 12 tons of bus started pursuing me across the parking lot. LUCKILY, a decorative curb stopped the bus by JUST catching one front tire. That could have happened from a child guest or even someone losing their balance.
Jim Bob |
Buswarrior (Buswarrior)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 01, 2006 - 8:41 pm: | |
Thanks Jim.
I'll e-mail coordinates.
Hope the maiden voyage goes well!
happy coaching!
buswarrior |
Greg Roberts (Gregeagle20)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 01, 2006 - 10:36 pm: | |
Since you replaced the most likely bad actor, the SR-1, the next valve I would replace is the R-14 relay that should be there in use for the park brake system. I expect there should be 4 total R-14 units on your three axle Eagle (the forth should be installed for the park brake system). I wouldn't completely rule out the SR-1, however. Was the SR-1 a rebuild? I have had several rebuilt units not provide good service so for another $40 I go for the new Bendix unit. |
Jim Shepherd (Rv_safetyman)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, March 03, 2006 - 12:27 am: | |
Greg, I think the SR-1 was new (purchased from Jefferson Bus). I think the relay valves on the Eagle are R8 rather than R14.
As I noted earlier, the system seems to be functioning properly after I replaced the PP1 (push pull parking valve). The service brake application seems to release the parking each time. That has been the case before, but then it goes south again. Lets hope that it continues to work and the PP1 valve did the job.
I have to comment that this has been one of the most in-depth threads I have participated in. Lots of good input and none of the “extraneous” stuff <grin>.
Thanks again to all of those that offered good thoughts!
Jim |
Greg Roberts (Gregeagle20)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, March 03, 2006 - 6:04 pm: | |
Jim,
I looked back through my written notes and was quickly reminded that the really bad actor with my Eagle was the SV-1. The little shuttle piston was pretty gunked up so I would check this if your Eagle has one. |
Jim Shepherd (Rv_safetyman)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, March 04, 2006 - 7:44 am: | |
Greg, I plan to disassemble both the SV-1 and DV4 valves when I get back from my trip. In the mean time, the brakes seem to be releasing just fine. Maybe the PP1 did the job.
Jim |
Buswarrior (Buswarrior)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, March 06, 2006 - 7:12 pm: | |
Hello Jim.
Thanks for those pages!
In my original doodling, I forgot to include a way to keep the parking brakes released, once you let go the brake pedal!
I like this circuit even more, now that I've seen the drawings! Great safety upgrade for a spring brake system.
I'm with Greg, that SV-1 is likely the squeaky hinge pin in this caper.
Have a good trip!
happy coaching!
buswarrior |