Foretravel Owners' Forum

Foretravel Motorhome Forums => Foretravel Tech Talk => Topic started by: Lance Camper on August 02, 2017, 05:08:18 pm

Title: Airing up tanks from tire air valve?
Post by: Lance Camper on August 02, 2017, 05:08:18 pm
I need quick answer.

The air valve near the propane tank. I use it to air up my tires etc.

Can this be used to fill my tanks so the brakes can be released.

Thanks
Title: Re: Filling tires - air valve on coach?
Post by: craneman on August 02, 2017, 05:11:29 pm
If you have a male to male adaptor it fills the tanks.
Title: Re: Airing up tanks from tire air valve?
Post by: Chuck & Jeannie on August 03, 2017, 08:54:59 am
Ed's question brings up the subject of providing a outside air source to your coach air system.  I think most owners are aware of this technique, but for the benefit of our newer members, it might be a good time to reiterate.

On many coaches, the tire air fill hose (or quick connect fitting if you don't have a hose) is supplied directly from your "wet" pressure tank.  This connection can be a convenient route to providing outside air pressure to your coach.  Why do you care about that?  If you ever need to have your coach towed, the tow truck operator will want to hook up a air hose from his truck to your air system.  Using the tow truck air pressure will allow him to release your parking brake, AND (with your ignition key "on") it will provide pressure to your suspension air bags to bring them up to ride height.  The other way to accomplish this is to leave your coach engine running (at idle) for the duration of the tow - not a desirable alternative.

The tow truck has a air dryer, so you don't need to worry about contaminating your air system with unfiltered air.  This is a good thing, because in almost any "tow" situation, you will already have enough other problems to worry about.  8)
Title: Re: Airing up tanks from tire air valve?
Post by: Mark Duckworth on August 03, 2017, 12:34:22 pm
In reviewing the air system drawing for our coach, I don't see how air from the quick connect port can get to the brake system.  It feeds the leveling system for sure, but if -- and this is a big if -- the system check valves and protection valves are operational, it doesn't seem possible to recharge either the front or rear tank on our 03 U320.

Is the 03 air system the same as the one under discussion?  If yes then I must be missing something.
Title: Re: Airing up tanks from tire air valve?
Post by: Chuck & Jeannie on August 03, 2017, 02:13:30 pm
In reviewing the air system drawing for our coach, I don't see how air from the quick connect port can get to the brake system.
No, you are right - this procedure would not work on your coach.  Your system is a whole lot more complicated than the older models.  On my '93, the tire filler air hose connection comes directly off the wet tank, and no check valves in the line.

Just quickly scanning your air diagram, I don't really see a good spot to tap into the air system with a external supply.  The drain valve on the wet tank would work, but it's not in a very convenient location.  OR, you could make up a little "Y" manifold so you could attach the external air hose to both the front and rear air tank drain valves (in front of the left front tire).  That should do the trick...

Thanks for pointing out the difference in models.  I tend to forget how much the coach systems changed from year to year.  :facepalm:

(I edited my post, above)
Title: Re: Airing up tanks from tire air valve?
Post by: Chuck & Jeannie on August 03, 2017, 02:32:37 pm
Photo below of a male/male adapter for connecting a external air supply.  IF connecting to the tire filler hose will work on your coach, then you could make one up ahead of time and carry it with you - might come in handy some day!
Title: Re: Airing up tanks from tire air valve?
Post by: wolfe10 on August 03, 2017, 02:40:38 pm
Be aware that there are several different styles of end fittings. They do not appear at first glance to be much different, but they are NOT interchangeable.

So, make sure you get the correct ones.
Title: Re: Airing up tanks from tire air valve?
Post by: gracerace on August 03, 2017, 02:45:31 pm
Photo below of the male/male adapter for connecting a external air supply. IF connecting to the tire filler hose will work on your coach, then you should make one up ahead of time and carry it with you - might come in handy some day!
Mine is just like that. But has a shut off in the middle.
Title: Re: Airing up tanks from tire air valve?
Post by: Mark Duckworth on August 03, 2017, 05:19:35 pm
Just quickly scanning your air diagram, I don't really see a good spot to tap into the air system with a external supply.  The drain valve on the wet tank would work, but it's not in a very convenient location.  OR, you could make up a little "Y" manifold so you could attach the external air hose to both the front and rear air tank drain valves in front of the left front tire.  That should do the trick...
Here's a 20,000' view of how mine is now plumbed. The green rectangles and blue arrows show how I get external air in via a multi-stage filter/dryer system.  The aux air system was originally the HWH compressor alone, but it is now the HWH, a Porter-Cable 110v compressor and a new dryer system.  There's a shut off valve between the aux air dryer and the wet tank.  The OEM shut off valve was a solenoid operated from the driver's console, but mine is a manual ball valve because the solenoid died.  My 110V compressor has female quick connect fittings and I have a male-male as pictured above.
 
In a tow situation I can have the air line from the wrecker connected to the 110v compressor's tank via the male-male adapter.  Then it goes through the ATD dryer.  Then I open the shutoff valve and it feeds the wet tank.

 More description is available in this previous post. (http://www.foreforums.com/index.php?topic=31691.msg280550#msg280550)
Title: Re: Airing up tanks from tire air valve?
Post by: Mark Duckworth on August 03, 2017, 05:45:58 pm
Mine is just like that. But has a shut off in the middle.
I'm going to add a shut off to my M-M adapter.  Great idea.
Title: Re: Airing up tanks from tire air valve?
Post by: Barry & Cindy on August 03, 2017, 05:50:35 pm
How can Ed & Michele's idea work?

Air hose is supplied from wet tank.  Wet tank supplies air to front brake air tanks.  Front air tanks feed air to brake canisters to compress parking spring and release parking brake.

Their idea sounds like perpetual motion. 
Title: Re: Airing up tanks from tire air valve?
Post by: wolfe10 on August 03, 2017, 05:53:23 pm
How can Ed & Michele's idea work?

Air hose is supplied from wet tank.  Wet tank supplies air to front brake air tanks.  Front air tanks feed air to brake canisters to compress parking spring and release parking brake.

Their idea sounds like perpetual motion. 

The air source is external-- supplied by a tow truck, etc.  That is why the male/male adapter.
Title: Re: Airing up tanks from tire air valve?
Post by: bbeane on August 03, 2017, 06:04:36 pm
I beleave my 99 has check valves in the air system that would prevent back feeding the air system from that connection.
Title: Re: Airing up tanks from tire air valve?
Post by: craneman on August 03, 2017, 06:12:59 pm
I beleave my 99 has check valves in the air system that would prevent back feeding the air system from that connection.
If that is the case my check valves don't work as I can raise the coach from the fill hose coupler. And release brakes. Both air gauges go to whatever pressure I put in it.
Title: Re: Airing up tanks from tire air valve?
Post by: Chuck & Jeannie on August 03, 2017, 06:31:33 pm
I'm going to add a shut off to my M-M adapter.  Great idea.
Me 3!  Excellent upgrade!  ^.^d