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Topic: U-320, on board air supply for external line (Read 837 times) previous topic - next topic

U-320, on board air supply for external line

Is the external air supply outlet capable of airing up the tires on coach? Air pressure on the coach is around 100-110. Logic tells me it would not be enough to do the job. Perhaps not enough reservoir either. I can see where it would be nice for airing up anything needing 50-60 lbs, IE. bikes, balls, etc. 

David West
David West
2001 U320 40'

Re: U-320, on board air supply for external line

Reply #1 –
David,

I guess the first question is what tire pressure you need to carry for your actual weight?

If over 100 PSI, yes, the fill will be SLOW.  But if you have a co-pilot who can lightly fan the brake pedal when air pressure drops from "cut-out" pressure, you will have pressure near the high end of your operating range available to air the tires.
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: U-320, on board air supply for external line

Reply #2 –
David,
We use ours when we are away from the barn to top off the tires and have never had a problem. You may have to wait on the governor to kick in but other than that we have never had a problem. Works great on the toad tires also.

Pamela & Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: U-320, on board air supply for external line

Reply #3 –
We run 90 psi front and 80 psi rear (cold tires/lowest ambient temperature). Michelin charts call for 85/75 for our axle weights. I have no problem airing our tires from the coach system. The best pressure seems to be at the time that the air dryer purges. I use a Milton fill tool with built in gauge. It makes the job much easier than using a gauge separate from the air chuck. I found Milton air tools at the local Parts Plus auto supply.
J D Stevens
1997 U295 CAI 36' Build #5085
2002 Subaru Outback
Motorcade 16869
Bellville, TX

Re: U-320, on board air supply for external line

Reply #4 –
Dear David.  Check my numbers, do not rely upon what I am telling you on that.  My coach is not a tag axle, I did not notice if you have a tag.  IF you are not running a tag, and your coach is like mine (2001 U320 40 ft) then I believe you will find that you need about 110 psi in the front tires (inflated when cool, as you know).

It is a problem to achieve that straight off of your air tanks on the coach.  In essence you have to put that air in the tire as the pressure comes up, as the compressor kicks in.  If you have say 100 lbs in your tanks, the compressor is not coming on (I think it will kick in about 90 psi) and you cannot put much air in the tire if you are at 100 in the tire.  The trick is to build a device that was explained earlier on the Forum, a very handy idea.  That is probably what J.D. is referencing but note that his tires, if I read this correctly, carry less psi than us and this method while good for him is essential for us.  Brett also gave you a way to get to this, have someone pump the air brakes to use up air, bringing the compressor on.

It can help if you install a pressure gauge in between your air chuck and the hose, you can monitor the pressure coming into the air chuck and that lets you connect the chuck at just the right moment, when compressor kicks on and the air pressure is building in your tanks.  It is in that building pressure that you can get the most air volume at your chuck and into the tire at the pressure you want.  I have not explained this well, but if you build the device and play with it, I think you will find it a benefit.  On the road, I use that.  At home I got a Porter Cable 150 psi compressor and it works well, but it requires the same principle.  To get to the volume I need in a tire, it helps to have the compressor running, not simply using out of the tank's air supply. I am making little progress, and slowly, until I get the compressor to kick on.  Sorry so convoluted a reply.    But try this if you still need an option.  I can send you a picture of what I built if you need, just drop me a PM.    Mike
Mike
2001 U320 4010 Build 5878 (Gus)
Wrangle Unlimited Toad
Nacogdoches

Re: U-320, on board air supply for external line

Reply #5 –
Quote from: Michael & Jackie –
It can help if you install a pressure gauge in between your air chuck and the hose, you can monitor the pressure coming into the air chuck and that lets you connect the chuck at just the right moment, when compressor kicks on and the air pressure is building in your tanks.  It is in that building pressure that you can get the most air volume at your chuck and into the tire at the pressure you want.  I have not explained this well, but if you build the device and play with it, I think you will find it a benefit.      Mike

I built something similar that works well and is very useful.
The selected media item is not currently available.Barry BEAM #16014
2003 U320 40' AGDS
Beamalarm, Foretravel technical help and specifications
"Whatever the mind can conceive and believe, it can achieve"

Re: U-320, on board air supply for external line

Reply #6 –
Thanks everyone. I thought it was going to be in the 'tricky zone' but wasn't sure what was procedure. I now know what to do. Will get an air chuck with a guage built in. I will learn by trial and error. Good to know the toad and other smaller items will be easy.

David
David West
2001 U320 40'

Re: U-320, on board air supply for external line

Reply #7 –
One thing I added to my tire air system is a check valve, which would keep air from the tire going back into the system while the compressor is building air pressure, this is good for higher pressure tire inflation. Also you can keep the chuck attached and  only one person is required to do the compressor activation procedure, even if the pressure goes beyond the target point, adjustments are a non event, usually 118-120lbs. would be highest, if your lucky. jc
JC
1999 U320

Re: U-320, on board air supply for external line

Reply #8 –
dwest, I carry 110 # in my steering tires. Getting these topped off was difficult until I had the bleed off valve on my engine compressor reset to 125#, yes, it is adjustable. Of course, the engine needs to be running.
No RV! Have hung up the keys.
In the past: 2016 Winnebago Era, 1994 Foretravel U240, 1995 Foretravel U240 (wide body), 1999 Foretravel 320, 36 Foot, 2003 Foretravel U320 38 foot,
 

Re: U-320, on board air supply for external line

Reply #9 –
I'm running a '96 U295. We've been fulltiming for 12 years. Our coach weight is about 28K. What in the world are some of you carrying that causes you to run 110 PSI in your tires? I run 85-90 PSI front and rear. Using Contenentals and very happy with mileage, ride, and handling. I con't muck around with the tires and pressure daily or even weekly. If I've been parked for a month or so I'll check and fill as needed before starting off. If tires are in the 85+ range I leave them alone. If they're below 85 PSI they are brought up to 90 PSI. I know people who check their tires daily and are probably taking out enough each time to cause them to need to add about the fourth or fifth tme. They then wonder why they need to add so often while I don't. I've been getting 6-7 years on tires before changing them on the "5-7 year" schedule based on sidewall wear-out. Happy Camper...not worrying about the tires.
Larry
1996 U295 36'
Build # 4805
Actually we sold it but just like to lurk