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Topic: Air System Components, What is it?  (Read 726 times) previous topic - next topic

Air System Components, What is it?

Hello All,
  This thing is under the water tank in between the D & P seats under the MH.  What is it? and what does it do?

Pat,
Pat/Blue Angel
1995 U240 36ft
MC# 16511
Build# 4653

Re: Air System Components, What is it?

Reply #1 –
From your question, I'm guessing you don't have a air system diagram for your coach?

If you had a diagram, you can often deduce the function of the component by looking at what air lines are connected to it, and where they go.

Can you follow the air lines under the coach?  Do you have air brakes on the U240?  It could be some kind of air brake distribution valve.

On my air system, air line 20 goes to the "Spring Brake Control Valve".  The other lines connected to that valve are 13, 17, and 19.

On my air system, the SBCV has something to do with either applying, or releasing, the spring brakes (parking brake).

That's about all I can offer.  Sorry.
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Air System Components, What is it?

Reply #2 –
That looks like a brake relay valve, just not the one I am used to.
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: Air System Components, What is it?

Reply #3 –
Quote from: pthurman48 –
Hello All,
  This thing is under the water tank in between the D & P seats under the MH.  What is it? and what does it do?

Pat,

Given its location, and that you have wedge style air brakes my wild-assed guess is that it's a quick release valve for the two front wheel brakes.  Its job is to go Psssshhhht when you let up on the brake treadle.
1992 Foretravel Grand Villa
U225 SBID Build No. 4134
1986 Rockwood Driftwood
1968 S.I.A.T.A. Spring
1962 Studebaker Lark
1986 Honda VF700C
1983 Honda VF750C
Charlie, the Dog was broken out of jail 24 Oct 2023
N1RPN
AA1OH (H)e who must be obeyed.

Re: Air System Components, What is it?

Reply #4 –
I have air s-cam brakes on the front and rear.  I am now replacing the air chambers(24x20 rears and type 16 front) tring to solve air leaks.  There are two(2) more of the things in the rear close to the pumpkin on the underside of the MH.

Pat,
Pat/Blue Angel
1995 U240 36ft
MC# 16511
Build# 4653

Re: Air System Components, What is it?

Reply #5 –
Quote from: pthurman48 –
I have air s-cam brakes on the front and rear.  I am now replacing the air chambers(24x20 rears and type 16 front) trying to solve air leaks.  There are two(2) more of the things in the rear close to the pumpkin on the underside of the MH.

Pat,
How come you got the S cam and I got the wedge?  No fair.

The two in the rear are pilot operated quick release valves to eliminate or at least mitigate the time delay in filling the rear air chambers.  The pilot operated part allows them to fill the brake chambers from an always full air line.  The quick release part allows them to dump the air locally.
1992 Foretravel Grand Villa
U225 SBID Build No. 4134
1986 Rockwood Driftwood
1968 S.I.A.T.A. Spring
1962 Studebaker Lark
1986 Honda VF700C
1983 Honda VF750C
Charlie, the Dog was broken out of jail 24 Oct 2023
N1RPN
AA1OH (H)e who must be obeyed.

Re: Air System Components, What is it?

Reply #6 –
Update:
  Some of the air leak issues was the air control valve (brake release knob).  I replaced all the brake air chambers, front new type 16 and type 24/20 on the rear.  On the way to Port Aransas, TX (Surfside RV Park), we noticed a thump under our feet when the MH hit large bumps.  Well when I checked this morning, guess what I found, the new brake air chambers on the front are hitting the frame/body of the MH.  Check out the pics.  The new ones are larger.

Holding 40 psi after 15 hrs.
Pat,
Pat/Blue Angel
1995 U240 36ft
MC# 16511
Build# 4653

Re: Air System Components, What is it?

Reply #7 –
If you turn the clamp it might clear but you don't want larger brake camber as it might effect the brake balance.
Peter and Frieda Morin
1999 36ft. U320 Foretravel
Build # 5436
1998 Suzuki Sidekick Sport

Re: Air System Components, What is it?

Reply #8 –
Hi Oldguy,
  The old chambers were smaller(mounting bolts, bolt patten, push rod, air chamber) and are a type 16 according to part numbers from FOT.  Old chambers part numbers are $115.00 and these are $40.00.  I will check to see what the $115 ones look like.

Pat,
Pat/Blue Angel
1995 U240 36ft
MC# 16511
Build# 4653

Re: Air System Components, What is it?

Reply #9 –
Update:
  Some of the air leak issues was the air control valve (brake release knob).  I replaced all the brake air chambers, front new type 16 and type 24/20 on the rear.  On the way to Port Aransas, TX (Surfside RV Park), we noticed a thump under our feet when the MH hit large bumps.  Well when I checked this morning, guess what I found, the new brake air chambers on the front are hitting the frame/body of the MH.  Check out the pics.  The new ones are larger.

Holding 40 psi after 15 hrs.
Pat,
Pat/Blue Angel
1995 U240 36ft
MC# 16511
Build# 4653

Re: Air System Components, What is it?

Reply #10 –
It looks like you could slightly loosen the double nuts on the retainer ring and rotate the ring down and around away from the frame. That may solve your clearance issues.
Craig & Jackie
1993 36ft Grand Villa
Unihome U-240 CAT 3116

Re: Air System Components, What is it?

Reply #11 –
Pat, I can't be sure however there's a bell going off in my head saying don't loosen that ring clamp, if memory serves me there's a spring in there that if released will take your teeth out. I seem to remember something about "T" shaped wrench to back off the spring or something, sorry I can't be more specific, probably craneman or someone will be able to shine a brighter light on the problem.
88 Grand Villa 36' ORED 3208 (throwaway)Cat.
 Build # 3150
Happiness is the maximum agreement of reality and desire.

Re: Air System Components, What is it?

Reply #12 –
Yes, spring applied, air released, BUT that is for the REAR BRAKES.

No so for the fronts.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Air System Components, What is it?

Reply #13 –
The brake chamber size indicates the square inches of the diaphragm contained within the chamber. If you have a type 12 chamber and you supply 50 psi of air pressure through the foot valve you are applying 600 pounds of linear force (50x12) to the slack adjuster. If you increase the size of the brake chamber you will be applying more force to the brakes causing them to be out of balance. This may cause the front brakes to lock up before the the rear brakes which is generally regarded as a bad thing.
If your coach was spec'd with type 12 brake chambers that is what you need to replace them with.

Also, in most cases you have a quick release valve only on the front brakes. You will have relay valves for each rear axle which speed up delivery of air to the the brakes as they are farthest from the foot valve. The relay valve also acts as a quick release valve.

Steve 
Steve & Sandy
2003 U320 4220 WCDS, build#6160
Motorcade #17794
USMC '67-'71

Re: Air System Components, What is it?

Reply #14 –
Quote from: Olde English –
Pat, I can't be sure however there's a bell going off in my head saying don't loosen that ring clamp, if memory serves me there's a spring in there that if released will take your teeth out. I seem to remember something about "T" shaped wrench to back off the spring or something, sorry I can't be more specific, probably craneman or someone will be able to shine a brighter light on the problem.

The front air chambers are single, and only apply the brakes with air pressure.

The rear air chambers are double diaphragms and a spring mechanism to apply the brakes when all air is released.  There should be a bolt to cage the spring for service.

I don't like to deal with springs.

Here is the first diagram I could find.

Brake Chamber K065544
1992 Foretravel Grand Villa
U225 SBID Build No. 4134
1986 Rockwood Driftwood
1968 S.I.A.T.A. Spring
1962 Studebaker Lark
1986 Honda VF700C
1983 Honda VF750C
Charlie, the Dog was broken out of jail 24 Oct 2023
N1RPN
AA1OH (H)e who must be obeyed.

Re: Air System Components, What is it?

Reply #15 –
Quote from: Old Toolmaker –
The front air chambers are single, and only apply the brakes with air pressure.

The rear air chambers are double diaphragms and a spring mechanism to apply the brakes when all air is released.  There should be a bolt to cage the spring for service.  If you don't have the caging bolt inserted properly it can come flying out with some force as you try to relieve the spring tension from the brake

I don't like to deal with springs.

Here is the first diagram I could find.

Brake Chamber K065544
1992 Foretravel Grand Villa
U225 SBID Build No. 4134
1986 Rockwood Driftwood
1968 S.I.A.T.A. Spring
1962 Studebaker Lark
1986 Honda VF700C
1983 Honda VF750C
Charlie, the Dog was broken out of jail 24 Oct 2023
N1RPN
AA1OH (H)e who must be obeyed.
 

Re: Air System Components, What is it?

Reply #16 –
When I first worked on maxi brakes you had to be really careful as the maxi part could be service. Then they got smart and made
them non serviceable, which made them a lot safer. It's been years since I change diaphragms, can they still bought. As CRDavis
said you just loosen the bolt in the clamp and tap it with a hammer to turn it out of the way. As Steve said you will have more
braking on the front.
Peter and Frieda Morin
1999 36ft. U320 Foretravel
Build # 5436
1998 Suzuki Sidekick Sport