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Topic: Air Supply on our 94 U240 - good for tire inflation? (Read 1306 times) previous topic - next topic

Air Supply on our 94 U240 - good for tire inflation?

We have an air hose with a "duster" handle on our coach.  A search of the forum showed several posts about supplemental supplies for use when the coach is not running, but not much otherwise.  Will this hose, with an inflator attachment, be adequate for topping-off tire pressure?

Matt B
1994 U-240
Matt B
1998 u-320

Re: Air Supply on our 94 U240 - good for tire inflation?

Reply #1 –
My experience with a 1997 U295 has been that I can easily air up the tires to about 95 psi with a hose connected to the air supply in the fuel/propane bay. I can get to 110 psi if I fill immediately after I hear the "whoosh" sound that occurs when the air system reaches maximum pressure. On our coach, the engine must be running in order to have enough pressure to properly inflate the tires.

I just fixed a fitting on my small electric air compressor and plan to carry it in the coach in order to generate compressed air when the primary engine is not running. The small electric compressor generates in excess of 120 psi of pressure at a volume sufficient to top off big tires. Other folk carry compressed air or CO2 in a portable tank.
J D Stevens
1997 U295 CAI 36' Build #5085
2002 Subaru Outback
Motorcade 16869
Bellville, TX

Re: Air Supply on our 94 U240 - good for tire inflation?

Reply #2 –
Thanks JD.  My inflator handle is headed for the bay!

Matt B
Matt B
1998 u-320

Re: Air Supply on our 94 U240 - good for tire inflation?

Reply #3 –
Quote from: oldmattb –
We have an air hose with a "duster" handle on our coach.  A search of the forum showed several posts about supplemental supplies for use when the coach is not running, but not much otherwise.  Will this hose, with an inflator attachment, be adequate for topping-off tire pressure?

Matt B

In a word, YES, this on-board hose will be fine to inflate the tires with the engine running.

Suspect your front tire pressure should be around 95 and rear around 85.  This to be confirmed by actually weighing the coach as loaded and then referring to your tire manufacturer's inflation tables.

Brett
1994 U-240
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 Supply on our 94 U240 - good for tire inflation?

Reply #4 –
On my coach I removed the air chuck from the hose and replaced it with a female air line connector, so that I can use air tools and also air up the coach without starting the engine by connecting to an external compressor.  Requires the proper adapters of course, and the air chuck has one so that I can still use it.  When using air tools, the coach air tank and engine compressor are rather small volume wise, so I idle the engine at 1000 rpm and wait for the pressure to build back up after a short period of use. 
Jerry Whiteaker former owner 96 U270  36' #4831 Austin,TX-Owner Mods LCD TV w/front cabinet rebuild - LCD TV bedroom - Dual Central AC, either can cool coach w 30 amp - Skylights at roof AC openings - Drop ceiling for ducting of AC - Shower skylight white gelcoat/wood/epoxy frame - Air Springs/Shocks replaced - 2014 CRV - 8K Home Solar - Chevy Volt

Re: Air Supply on our 94 U240 - good for tire inflation?

Reply #5 –
I use mine but still look for a small unit to carry in the bay.
David in VA
1994 Unihome Grand Villa U280

Re: Air Supply on our 94 U240 - good for tire inflation?

Reply #6 –
One thing the onboard compressor has that an external compressor probably does not have is an air dryer.  Dry air or nitrogen is supposed to help the tires by causing less pressure change when the tires get hot and having no water in the tires cuts down on corrosion of the wheels.

See the article, www.getnitrogen.org/pdf/print_articles/Bridgestone_FirestoneCommercialTruckTires.pdf 
John Cooper
'91 GV 36'
Oshkosh chassis
Cat 3208T 300HP

Re: Air Supply on our 94 U240 - good for tire inflation?

Reply #7 –
The trick to airing up tires from the coach air supply is to run the engine at fast idle.  I use a chuck with a built-in air gauge (Tractor Supply)  so I can watch the building pressure and achieve the setting I want for the front tires-110psi in my case.
Regards,
Brett

'99 42' Foretravel Xtreme
'14 Brown Motorsports Stacker
'05 Chevy SSR
'02 BMW R1150R

Re: Air Supply on our 94 U240 - good for tire inflation?

Reply #8 –
I made nearly the identical chuck with gauge, made from Harbor Freight parts a couple of years ago.  I used it again today, with the engine running at fast idle.  Works great.
Tom Lang K6PG (originally  KC6UEC)
and Diane Lang
2003 38 U295 build 6209
2016 Jeep Grand Cherokee Summit Ecodiesel
still have tow-ready 2006 Acura MDX 
Temple City, California
Motorcade 16681 California Chapter President
SKP 16663 member of SKP Park of the Sierra, Coarsegold California
FMCA F071251
Retired electrical and electronic engineer

Re: Air Supply on our 94 U240 - good for tire inflation?

Reply #9 –
I learned a technique to running the engine at fast idle while at my recent service trip to MOT. 
    • Ensure transmission in Neutral and Emergency brake is ON
    • Accelerate engine to desired RPM
    • Activate Cruise Control
    • Press Set button
    • Cruise Control will hold engine RPMs at desired level
Ron Sedgley
Former 2002 U320 - Custom 38' Owner
            (2007 to 2021)    Build No. 6001

Re: Air Supply on our 94 U240 - good for tire inflation?

Reply #10 –
At least on the 1993 Caterpillar 3116 (and I expect will function the same on the 1994 model), to engage fast idle, merely turn cruise control on (yes, in neutral) and roll the switch to "set".  Then roll to "accelerate" until the desired RPM is reached.

This worked with the OE Bendix CC and with the replacement electronic cruise from King Control I went to years ago (same steering column-mounted stalk).

Brett
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 Supply on our 94 U240 - good for tire inflation?

Reply #11 –
Using the accelerate button seems to be a better controlled way Brett!
Ron Sedgley
Former 2002 U320 - Custom 38' Owner
            (2007 to 2021)    Build No. 6001
 

Re: Air Supply on our 94 U240 - good for tire inflation?

Reply #12 –
Ron,

I suspect our cruise control systems are VERY different, but will give it a try.

Thanks.

Brett
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