Skip to main content ↑ ↓
Topic: Compressed air systems  (Read 606 times) previous topic - next topic

Compressed air systems

I am trying to understand how the two compressed air systems work and which equipment they support.

I just replaced the regulators for the step and step cover. Now I need to adjust them to 50 psi, but I have no air pressure in those lines from the auxiliary compressor. So I am assuming that the engine-driven compressor supplies air to the step and step cover. I have not been able to find a discussion of the two compressed air systems detailing which equipment each supports. Can someone please point me to such a document?
Royce & Denise, MC #17410
'01 U320 4220 ISM450 Build #5895 SOLD
Toad: '10 Honda CR-V

Travel makes one modest. You see what a tiny place you occupy in the world. - Gustave Flaubert

Re: Compressed air systems

Reply #1 –
I am not sure if there is a single document or thread that describes the Aux. Air Compressor and the Engine Air Compressor. 

You can spend alot of time on the Search function here and look at lots of docs. at:  Foretravel Motorhome technical help and information links

Aux. Air Compressor:  Supports the Air Bladders, large Zip Dee Awning and HWH Leveling system/Air Bags mostly while stationary when the engine is not running.  There is an Aux. Compressor Switch in the driver's left panel that will start the Aux. Air Compressor to fill air tanks that can be used to inflate air bags to get to Travel Height without starting the engine air compressor.

Engine Air Compressor:  Supports the Air Brakes, HWH Leveling System, Ride Height and such, as well as keeping air in the Slide Bladders.  The engine air compressor also supports the front step.

I am sure my attempt at explanation will be corrected by others here.  :D
Scott & Carol Seibert
2001 42' double slide U320 - Sold
Previous - 2002 36' U320

Re: Compressed air systems

Reply #2 –
Thanks Scott. I searched beamalarm.com as well as here but found nothing that would really help me. In fact, I am still searching for step cover info.
Royce & Denise, MC #17410
'01 U320 4220 ISM450 Build #5895 SOLD
Toad: '10 Honda CR-V

Travel makes one modest. You see what a tiny place you occupy in the world. - Gustave Flaubert

Re: Compressed air systems

Reply #3 –
Sorry I did not address the entry step issue.  Perhaps you will find what you are looking for here: 

How the inside step slide and outside step operate [ForeForums Foretravel...

When researching a topic I often look at Barry's Topic  "RV Technical Help"  at the top of his page.  If nothing jumps out at me from there I will use his "Search" function and if not there I will search this web site.  I usually find what I am looking for.  Worst case I will do what you have done and post.  Many of the topics/questions that we see here have already been asked in one form or another.  I do not think any FoFum members mind seeing questions resurface and will readily assist when they can.  It's a sort of paying it forward.  Carol and I certainly could not have existed and continued along our path had it not been for our FoFum members answering my/our questions.

Good luck.
Scott & Carol Seibert
2001 42' double slide U320 - Sold
Previous - 2002 36' U320

Re: Compressed air systems

Reply #4 –
I do not think the 12 volt air compressor supplies the step or the step cover. 
2025 Wanderbox Outpost 32 on F600 Expedition Motorhome
2015 Born Free Royal Splendor on Ford 550 nonslide version  for sale
Former Coaches  covering. 360,000 miles
1999 34 U270
2000 36 U320
2001 42' double slide U320
2018 Jeep Rubicon

Re: Compressed air systems

Reply #5 –
Quote from: John S –
I do not think the 12 volt air compressor supplies the step or the step cover. 

It doesn't supply the step or step cover on our 1995 U320.
David and Carolyn Osborn
1995 U320C SE 40' Build 4726 Feb 1995
FMCA 147762
Motorcade 17186

Re: Compressed air systems

Reply #6 –
Here's what happens:
Say you stop your engine with 115 lbs of air in the TANKS. All of your devices that are air operated will function from that air in the tanks UNTIL the volume of air depletes to less than whatever the pressure regulator for that device is set for.

However, the AUXILIARY compressor will ONLY operate HWH devices and DOES NOT add air to the tanks. So.......if your step regulator is set at 60 lbs, then when the air in the tanks gets around <60 it will stop activating until the pressure gets  >60 and this can only be done with the engine compressor adding air to the tanks.

In leveling, for example, the air will be RELEASED from the tanks (via the bag relief valves) and lower the high side until the pressure in the tanks is below around 80 lbs when the auxiliary compressor regulator kicks in and after that.......the aux compressor  will come on and RAISE the low side. It will no longer release air to lower unless you hit the dump button or down arrows.

The aux compressor is an HWH device and not intended to add air to anything except the bags. Unless Foretravel has changed their engineering in newer motorhomes that's it in a nutshell.
1994 U280, Build 4490
Deming, NM.
 

Re: Compressed air systems

Reply #7 –
Twig said "if your step regulator is set at 60 lbs, then when the air in the tanks gets around <60 it will stop activating until the pressure gets  >60"

While what Twig says does happen (i.e. no step air when tank pressure under 60 psi), the reason is not correct.
The step regulator (set at 60psi) will not allow the pressure at the step to exceed 60psi but would allow lower tank pressure to reach the step. However, between the tank and the step regulator is a protection valve set to circa 60 psi and it is this valve which will stop tank air pressure from reaching the step regulator when the  tank pressure is under 60psi. This feature is there to preserve air pressure for the brakes in the event of a sudden air leak when driving.

Sorry Twig, but gotya!
Wyatt
96 U320 40 WTFE, build 4943
84 Toyota Supra towd
2015 Jeep Wrangler towd
Victoria, BC, Canada