| Author |
Message |
david anderson (Davidanderson)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, February 09, 2006 - 6:21 pm: | |
Without a bunch of explanation, I needed to move my rear brake air tank to a location in the front. Now, I'm rerouting the lines. In doing this I need to mount a 1/2" line from the tank to the rear brake relay valve. I need to safely run this under the bay. I cannot get it through the tunnel without days of work.
I'm considering using 1/2" galvanized pipe from front bulkhead to the back bulkhead just forward the brake relay valve. The tank connections on the front and valve connections on the back will be made with approved DOT brake hose. The steel pipe would give good protection underneath from road debris and provide some degree of safety in case I ever hit high center and cruched the line. (hope that never happens)
My hesitation in doing this is: 1) I've never seen any steel pipe on any bus or truck equipment making me wonder if it is non approved engineering.
2) Possibility of some rust in the line blowing into the valves in years down the road which may compromise safety.
What sayeth the busnut board of directors??
David Anderson |
jimmci9 #2
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, February 09, 2006 - 7:17 pm: | |
since the early 90's new trucks have used nylon tubing... trade name synoflex... it uses an brass insert with a brass ferrule in a brass compression fitting...fittings for 1/2" are costly.. probably $3-4 each... depending on where you buy them... but you're paying for DOT approved type tubing and fittings.. the tubing will be marked with the DOT approval markings... i paid $0.79 ft for 3/8".... so the 1/2" stuff will probably be over a dollar...thr newest brass fitting have a push-in style feature.. similar to the chinese finger catcher type toys... |
Tim Jones (Torquester)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, February 09, 2006 - 7:37 pm: | |
If it is not stamped with a DOT approval (NTA) it is not approved for use in air brake systems. I would also caution you about relocating that tank so far forward without considering that you might need a larger line to supply the volume of air needed without too much pressure drop. Moving this stuff around without doing the engineering can effect brake timing.
hth, Tq |
Gus Causbie (Gusc)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, February 09, 2006 - 11:31 pm: | |
David,
Contrary to my usual postings, this is going to be a bunch of explanation because it is necessary in this case.
The rear tank is there to serve the rear brakes.
The relay valve, activated by the brake application valve (Foot pedal) , releases air directly from the rear tank to the rear brakes so air doesn't have to travel all the way from the front. This is not just air pressure, this is air volume moving.
At the same time the brake application valve releases air from the front tank to the front brakes so there is no time difference between the front and the back.
So, it is obvious that moving the rear tank to the front will destroy the timing of the brake application.
I wouldn't advise moving the tank as it is part of the basic brake setup and is standard on trucks and buses.
If you move the tank to the front I'm guessing you will need at least a 1" line to the rear brakes and probably larger if you expect to have anywhere near normal braking. If you move the tank forward there is no point in having a relay valve because there is nothing in the rear for it to relay?
In summary, this is probably illegal and will save you a lot of work if you don't do it. |
John MC9
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, February 09, 2006 - 11:55 pm: | |
David -
There are some things in life you just shouldn't try to re-engineer;
Brake systems are one - listen to Gus. |
david anderson (Davidanderson)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, February 10, 2006 - 1:27 am: | |
I appreciate the input. I figured the steel pipe would be a no-no. I can insert the proper DOT line into a pipe sleeve for protection.
However, the rear air tank still provides air to the relay valve. The 1/2" ID line is always under 90 to 120psi at all times from the tank. The pedal valve still gets the air from the rear tank via its original 3/8" ID air line. The rear tank will still get its supply from the 5/16" ID line from the wet tank.
The 5/16" and 1/2" line will go from 5' to 25'.
The 3/8" line will go from 25' to 5' The plumbing stays the same as per the eagle manual. Only the tank placement is changed.
From reading Gus's post I conclude that the volume of the compressed air is reduced significantly because of the 20' travel distance, compromising the timing of the rear brake application in relation to the front brakes.
The reason for the relocation is the installation of air bags on the drives. I've seen several eagles with air bags and there is no way to install these without relocating the rear tank. The tank is right over the top of the curbside torsalatic beam. Somehow, this has been done. I hope someone will post how they solved their tank location problem.
Catskinner, where are you??
David Anderson |
Bryce Gaston (Busted_knuckle)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, February 10, 2006 - 1:32 am: | |
DON"T DO IT! The responses above are all correct! These systems are designed with efficency, and safety in mind, last time i saw someone relocating things for conveinence they butchered the system causing a tragic failure, which caused a terrible accident, with fatalitys! The "modifier / owner / nice fellow" is still doing time for wreckless homicide(for tampering with original equipment design) and his family are still paying off on the lawsuits that were way above what the insurance was forced to pay(they tried to get out of paying any of do to his neglegence, but the judge made them pay the maximum coverage on his policy, but then he was left owing the balance I don't recall the amounts but it ain't worth it!) |
Bryce Gaston (Busted_knuckle)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, February 10, 2006 - 1:37 am: | |
David if you must move the air tank reolcate it near where it is now and try to keep the lines close to the same length if not, go aup in size but I by no means would move that tank out of the general area it is designed to be in! |
Phil Dumpster2
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, February 10, 2006 - 3:26 am: | |
There is a way to safely do what you want. You will need a smaller tank in the back feeding the relay valve supply port. This tank needs to be large enough to provide several full brake applications.
The wet tank feeds this tank. This tank will feed, via a pressure protection valve in the 110psi range, a larger tank elsewhere on the coach. That tank will have a second line feeding back to the smaller tank via a check valve to prevent reverse flow from the small tank to the larger tank.
It is probably a bit more than what you were planning on. |
Richard Bowyer (Drivingmisslazy)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, February 10, 2006 - 8:56 am: | |
David, call the boys at Southern Oregon Diesel. I was parked beside an Eagle they were putting rear air bags on, but I really did not pay much attention to what they were doing. Dave Gregory is who you need to talk to. Check BNO home page for a phone number.
Richard |
Sonnie Gray (Catskinner)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, February 10, 2006 - 9:46 am: | |
David
I relocated my new tanks to the inboard
side of the frame, underneath the tunnel
in that area.
David if you have any questions, call me.
Catskinner!
Sonnie Gray
0/5 Eagle 3406 Cat
Pottsboro, Texas |
Sonnie Gray (Catskinner)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, February 10, 2006 - 9:52 am: | |
David
Sorry, I forgot to post my number, 903 815-2141
Sonnie |
david anderson (Davidanderson)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, February 10, 2006 - 9:15 pm: | |
I called Dave Gregory at Southern Oregon Diesel. He said I could place the tank anywhere I wanted as long as the hoses were DOT. No loss of effectiveness would be noticed and no change in the braking logic would take place. However, he said I'd be disappointed with the air bag leveling and recommended a hydrolic system.
With that said, I think I'll just abandon the project. Norris from Jefferson Truck and Bus faxed me, this morning, the Eagle diagram of the factory air bag installation and the mounting configuration was exactly how I was going to fabricate mine. Who'd a thunk that?
The tanks were still in the back, but I think the frame structure was a bit different from my model 10, or the tanks are smaller (2 instead of 1). Doing that may work on mine to forego the tank relocation for the air bag bracket placement.
Anyway, I'm giving up for now.
David Anderson |
Tim Jones (Torquester)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, February 10, 2006 - 11:14 pm: | |
"no change in the braking logic would take place"
I do not believe that is true. I just needed to say that. If anybody really cares about the reasons why, just ask and I shall explain.
Tq |
John MC9
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, February 11, 2006 - 12:47 am: | |
No need to, Tim. It's a "no brainer". |
Gus Causbie (Gusc)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, February 11, 2006 - 12:47 am: | |
Tim,
I agree, there is no way a tank in front could deliver the same volume of air through the same size line to the rear brakes. This air is moving to the brakes and out, it is not just a pressure thing. Volume is the issue here.
Eagle systems must be different. My wet tank and rear tank are one and the same??
No reason two smaller tanks woudn't work, or a long and skinny tank.
Phil,
You really lost me on that one!! |
Buswarrior (Buswarrior)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 14, 2006 - 5:02 pm: | |
Buyer beware...
There are mechanics, and there are engineers.
There are people who are paid to design things.
There are people who are paid to replace broken parts.
Sometimes these two sets of people get confused and with no one to straighten them out, pretend to be the ones they aren't.
For brake related advice, Bendix is where to go.
The area field engineers from Bendix are a great wealth of information on both theoretical and applied subjects.
Now, be fair, in this lawsuit crazy world, they won't tell you exactly how to replumb your bus, but they will be able to furnish you with the right info to make responsible choices for yourself.
My inclination is keep it stock, or faithfully duplicate a more modern system from a later or similiar model. Every turn and every fitting changes the volume of air and the timing of application.
Half measures are just that.
happy coaching!
buswarrior |