We brought our U280 home from storage for some remodel work and when the cruise was turned on we ended up with an air leak from the the valve (I believe its a valve) in the photo. It would drop the from 110 psi to 90 and then fluctuate for the rest of the 40 minute trip. My question is can these valves be rebuilt and what kind of problems might i run into if I disassemble this thing? We leave for South Texas in 3 weeks so I need it to be right.
(https://www.foreforums.com/imagecache.php?image=http%3A%2F%2F20200222_124047.jpg&hash=07a8994ff8a98a4cf43e3fd2ce04cf08" rel="cached" data-hash="07a8994ff8a98a4cf43e3fd2ce04cf08" data-warn="External image, click here to view original" data-url="http://20200222_124047.jpg)
Try uploading your picture again. Thanks.
jk
Below is a "edited" diagram of the Bendix cruise control with lines added by Foretravel to tie in the air throttle system.
Which item on the diagram is leaking? Some of those parts are available off the shelf - some are "unobtainable".
Hopefully you have a "easy" to fix leak.
Thanks Chuck! For whatever reason my photo wont upload. I did break out the manual and found that it's the RV-1 pressure reducing valve and looking at your diagram, should be set to 60 psi. They look to be available online.
Whenever I need parts for our air system, I first go looking on eBay. I've had good luck finding NOS (New Old Stock) Bendix valves there at very reasonable prices. They always work fine, even if they have been sitting on a shelf gathering dust for years.
The RV-1 is adjustable, so if it isn't the correct pressure setting out of the box you can always fix that.
I *think* Festo has in the Festo Tiger Classic line an air valve that will do the job, and I'm sure they have a single acting cylinder that connected to a new bowden cable will open and close the "throttle."
At least that's my backup plan.
OK, so I replaced the RV-1 pressure reducing valve and stopped that leak. The coach is doing the same thing as before while driving though. I notice that pressure holds fine until the parking brake is turned off. The pressure will drop 10 to 20 PSI almost immediately. I've have previously replaced the main line from the compressor to the dryer due to a leak on a trip last year. We built up pressure to 110 psi, then having my wife shut down the engine and turning off the parking brake while I lay under the coach to listed for leaks and found nothing leaking (it was chalked and on level ground). Then we did the same thing and listened for leaks at the rear parking brakes and heard nothing. I'm at a loss so any suggestions are appreciated.
Does it continue to drop or does it stop at 10 to 20 psi. when you release the parking brake?
It drops 10 to 20 psi when the parking brake is turned off.
That might be what it takes to fill the brake release chambers if it starts building back up from there.
Do you see the pressure drop in both tanks, or just the rear brake tank?
And, after the pressure (?one tank or both?) dropped, what was the "recovery time" back up to cut out PSI assuming at 1,100 or so engine RPM?
Both tanks. sometimes it took a while to recover and others it recovered quickly.
I do not think you have a problem any more. The pressure is going to drop once you release the parking brake because the parking brake canisters are taking on air to push against the springs that are trying to apply the parking brakes.
But, the drop should ONLY be until the next "compressor on" cycle. Once cut-out PSI is reached, it should not continue to be low.