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Author Topic: Eagle Experts: Model 01 Brake issue "update"  (Read 2724 times)
wildbob24
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« on: June 11, 2010, 04:00:10 PM »

Guys,

I'm helping a friend move a '61 01 he just purchased and I'm trying to diagnose a brake problem. The bus airs up OK, but the foot valve only applies the front brakes and not the rears. The rears can be applied with the old ICC valve and they appear to be working well with this valve, but not with the foot valve.

I thought there might be a problem with the foot valve, but there is only one line in and one line out. It seems to me if it's applying the fronts it ought to be able apply the rears as well. Couldn't find any thing disconnected.

Two questions:

Is there another component between the foot valve and the relay valve that could be causing a problem?

Does anyone have a copy of the 01 air system diagram they could scan and email to us?

Any help would be much appreciated.

Bob
« Last Edit: June 19, 2010, 09:15:19 PM by wildbob24 » Logged

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DaveG
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« Reply #1 on: June 11, 2010, 04:08:16 PM »

I would expect there to be a relay valve for the front axle and a relay valve for the rear axle/axles. If you don't get an expert response in a timely manner, try looking from the rear brake cans forward until you find the relay valve for the service brake chamber...check to make sure it is getting air from the air tank, and signal from the foot valve. Maybe there is not air in the correct tank? Can you air up the bus and then check each tank at their respective drain valves?

Remember, I don't actually own a bus!
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« Reply #2 on: June 11, 2010, 04:09:33 PM »

Bob, is the parking brake applied while checking the foot pedal? If it is , when you apply the brakes (foot pedal) you will only notice the steer and bogie's being applied as the parking brake is only on the drives.hope this helps some, I'm sure the Cavalry will be by shortly  Grin good luck
« Last Edit: June 11, 2010, 04:11:41 PM by van » Logged

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wildbob24
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« Reply #3 on: June 11, 2010, 04:38:52 PM »

Thanks for the replies so far.

I must admit that most of my expertise lies with GMs and MCIs. I've done some engine and suspension work on Eagles but never messed with the air systems much. On the early GMs, with the single circuit system, there is no front relay valve, only one in the rear. I am assuming these old Eagles are generally the same.

There is no parking brake(Springs or DD3s), only the ICC control, which is only good as long as there is air pressure. We did check the brake operation with the ICC control off.

The ICC emergency brake control does operate the rear brakes through the relay valve. That tells me that that part of the system is functional. So, apparently somewhere between the foot valve and the relay valve there is a problem. There is no audible leak when the foot valve is applied, like I'd expect with a disconnected line.

I was wondering if there might be a check valve or protection valve plumbed in there that might cause this problem.

Keep the suggestions coming.

Thanks,

Bob
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bevans6
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« Reply #4 on: June 11, 2010, 04:41:02 PM »

On my bus, which is a 1980 MCI, the treadle valve applies air directly to the front brakes via a quick release valve only, and that same line applies air to the relay valve in the back (no check valve).  So if there is air to the fronts there is air to the relay valve.  It uses that air as a signal to allow air to be sent to the rear brakes directly from the dry tank.  Now, that is a DD3 type system and may be totally different, but I thought I would at least try...  the spring brake systems I have examined were  quite similar, but when they get into split front/rear systems the rules change a bit.  My take from what you've said is a bad relay valve.


Brian
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« Reply #5 on: June 11, 2010, 05:38:38 PM »

I have a complete Eagle 01 manual in pdf that I can send you. Let me know where.

It does list some 05 stuff, but mostly 01. The air system is in Group 12.

The air system in the Eagle 01 is probably like any other, foot valve, relay vavle, check valves etc.

 I'm not familiar with ICC.

What is his VIN#? Should be a four digit number.

Let me know.

Paul
« Last Edit: June 11, 2010, 06:04:38 PM by Dreamscape » Logged

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« Reply #6 on: June 11, 2010, 06:19:42 PM »

Paul,

That would be great. My email address is listed in my profile, but it is: wildbob24atbellsouth.net.

My first thought, when they told me that neither rear brake was working,was, as Brian said, that the relay valve was at fault, . However, the relay valve is working when the ICC valve is applied, so logic tells me that it should work when the foot valve is applied as well.

The ICC brake valve is also called an auxiliary brake control. It was mandated by the now defunct Interstate Commerce Commission to provide an emergency method for applying the brakes on the rear axle. It's a small lever operated valve found on the older buses, usually mounted beside the driver's seat. It's pretty much "on" or "off", no modulation.

So, I am looking for something between the foot valve and the ICC valve(or relay), like a stuck double check valve or air pressure cut-off valve. The old GMs have these and I'm hoping that Paul's manual will show if the Eagles used these and where they might located.

Paul, the serial # is 58163. As of today, it belongs to Mark aka "crazy4buses". I believe you and he have corresponded about this bus on the Eagle site.

Thanks,

Bob

« Last Edit: June 11, 2010, 06:27:47 PM by wildbob24 » Logged

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« Reply #7 on: June 11, 2010, 06:27:50 PM »

Bob,

I sent you a PM, the email you provided does not work.

It does show the valve you mentioned, they call it an Emergency Stop Valve.

The VIN you listed is not a good number, it should be a four digit starting with 6101.

Paul
« Last Edit: June 11, 2010, 06:33:33 PM by Dreamscape » Logged

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« Reply #8 on: June 11, 2010, 07:10:11 PM »

What kind of rear brake chambers does the Eagle 01 use?

Brian
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« Reply #9 on: June 11, 2010, 07:15:27 PM »

Brian, the 01 had DD3 they never used the ICC like old GM buses  


good luck
« Last Edit: June 11, 2010, 07:18:40 PM by luvrbus » Logged

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wildbob24
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« Reply #10 on: June 11, 2010, 07:25:27 PM »

Paul,

Received the manuals....should be most helpful. Thank you very much.

Clifford,

We must have an oddball, then. This one definitely does not have DD3s and does have a functional ICC valve.

Bob
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« Reply #11 on: June 11, 2010, 07:32:43 PM »

American could have ordered it with ICC they did weird stuff but the standard was DD3 ,they were the NJT of the 60's.Check the cans and see if they are ICC or DD3
« Last Edit: June 11, 2010, 07:41:53 PM by luvrbus » Logged

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wildbob24
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« Reply #12 on: June 11, 2010, 08:22:26 PM »

Clifford,

I crawled under the bus to check the operation of the brake chambers, and they are definitely not DD3s. There is only one service line going to each can from the relay valve. No other hoses and no parking function at all.

Doesn't make any sense to me, as Paul's manuals show DD3s. Perhaps, as you said, American ordered it this way to save a few bucks.

Bob
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« Reply #13 on: June 12, 2010, 04:47:06 AM »

Depending on the plumbing you might be best to switch over to Spring Brake cans. I removed our DD-3's and did just that, much better results and you can get them pretty cheap. There are directions over on the Eagle site.

Does it have a PP2 park valve?

Here is a picture of our E-1 treadle valve

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« Reply #14 on: June 12, 2010, 07:34:35 AM »

Going with the story so far, there should be something to keep the ICC feed and the brake pedal feed to the rear relay valve separate.

Otherwise, the ICC circuit would back feed to the brake pedal and put the front brakes on too.

Perhaps a stuck double check valve blocking the brake pedal signal?

I'd expect that such a check valve would be up front somewhere, in order to economize on piping.

Down under the front, see of you can trace down from the ICC as well as from the brake pedal, it won't be far away, me thinks!

happy coaching!
buswarrior

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wildbob24
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« Reply #15 on: June 12, 2010, 09:07:47 AM »

Paul,

No PP2 valve on this bus. The treadle valve looks like the one in your picture, but there are only two lines connected to it. A supply and a delivery.

I agree that a spring brake conversion should be in this bus's future, especially since it has no parking brake at all. Right now, we're just focused on getting it moved from the previous owner's property to the new owner's property.

Bob
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« Reply #16 on: June 12, 2010, 09:22:26 AM »

BW,

That's what I'm leaning toward, based on my GM experience. Makes the most sense to me.

We looked up under the front and couldn't see anything but pipes, but we'll have to go back and look harder to find that check valve.

Thanks,

Bob
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Len Silva
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« Reply #17 on: June 12, 2010, 09:33:38 AM »

FWIW, I have a 4104 maintenance manual here:  http://manuals.lenstudio.com/GM_PD4104MaintX-5818.pdf

Scroll down to Section 4 for an air brake schematic, might give some help.
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wildbob24
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« Reply #18 on: June 12, 2010, 09:57:20 AM »

Len,

Thanks for the suggestion and link. I have a 4104 manual in my library and didn't think to consult it.

If the eagle plumbing is the same (and I believe it is), then the double check valve between the treadle valve and the ICC valve must be the culprit.

Now all we have to do is locate it.

Thanks,

Bob
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« Reply #19 on: June 19, 2010, 09:22:40 PM »

To update this thread:

This morning, after much moaning and gnashing of teeth, we located the double check valve. It's up under the center of the bus in the space just forward of the first bay bulkhead.

We removed it and sure enough it was stuck. Cleaned it up and reinstalled it but we couldn't test it because the batteries were dead and we were unable to build any air pressure. I feel confident this was the source of the problem.

I appreciate all the help and suggestions.

Bob
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