Community Forums

dansawyer · 04-28-2023, 08:26 AM

Good morning. I am chasing a couple of questions about how the air ride system works.

The first question is: Is the leveling process controlled strictly by air pressure or it is controled by DC voltage, i.e. the ignition being on?

I am observing it appears to be independent of DC power. That is I am observing the levelers are mechanical and not electrical. If there is air pressure in the tanks then the levelers will work. Is this correct?

The second question is: How does the above relate to the dump valve switch and air dump process? If my understanding is correct the dump valve is connected to the air bags and is supposed to dump air from the bags. On my rig I observe the dump valve is definitely connected to the ignition circuit. It is electrical. Based on this my assumption is when the dump valve is operated it not only dumps air from the bags; air is also flowing from the tanks through the levelers, into the bags, and then out through the dump valve. That is this process will empty the tanks before the vehicle actually lowers.

Do I have the basic relationships correct?

Thanks in advance, Dan

Skip426 · 04-28-2023, 10:18 AM

Dan ; there are differences between ; air suspension operation ( with hydraulic levelers ) and an air leveling system's operation .

Which system does your coach have ?

Is this question about the 39' National Tradewinds in your " About me " ?

dansawyer · 04-28-2023, 11:08 AM

Thank you for following up. Yes. It is the 2002 National Tradewinds 390 LE on a Spartan Chassis.

I observe that the leveling controllers are mechanical. When there is air in the tank and the levelers are 'operated' air flows into or out of the bags. Based on this I speculate the leveling operation is mechanical.

Rob_M · 04-28-2023, 11:38 AM

I’ve not seen air levelers on a 2002 Spartan MM chassis. Mine has a 3 leg hydraulic leveling system. When I start to use the levelers it automatically dumps all the air out of the suspension air bags some call them air springs.

What do you mean by mechanical?

Edit: All of the air valves are electrically controlled except for the air ride height control valves which indeed are mechanically attached to the suspension components to regulate ride height while engine is running and leveling jacks are up.

It will either have one in front and 2 in rear or visa-versa.

dansawyer · 04-28-2023, 03:38 PM

Whoops. I have totally crossed terms. My bad.
I should have said air ride adjustors. I should have said the air ride adjustors are mechanical.

(You are correct about the levelors. They are hydraulic.)
This whole thread is about air ride adjustors. I am chasing an air leak and an rv list, the drivers side is high.

Ray,IN · 04-28-2023, 04:26 PM

This is the compressed air system for a Spartan MM chassis, hope it helps you understand how it works and why.
The air spring dump valves are indeed operated by 12V solenoids, and they are not supplied by Spartan, they are installed by the MH mfgr.

As to one corner being too high; that means ride height must be adjusted to Spartan specs. This can be dangerous/ or even deadly to adjust if the proper precautions are not taken.

Ray,IN · 04-28-2023, 05:52 PM

I forgot to say; the most important thing the compressed air system does is provide braking, but that is another discussion.

Skip426 · 04-28-2023, 06:45 PM

Quote:

Originally Posted by Ray,IN

I forgot to say; the most important thing the compressed air system does is provide braking, but that is another discussion.

Yes ; BUT ; Dan also mentioned his dump valve is completely draining the tanks , so a bad PPV ( Pressure Protection Valve ) to shut down air supplied to the air suspension at approx 65 psi has to be investigated.

Dan , a PPV is installed between the air suspension system and the air brake supply tanks to prevent complete air pressure loss in the event of an air bag blow out.
The air suspension would collapse , but the saved air pressure in the tanks would prevent the auto engagement of the park brake ( 45 psi) and allow the coach to be carefully maneuvered to a safe parking spot .

dansawyer · 05-24-2023, 09:41 AM

Good morning. I have been pulled into surgery recovery support so have had other things in front of this.

My plan is to bring the RV home this weekend and set up a 'test' in the dirve way. I will charge up the tanks and then look for leaks. My suspicion is it is the suspension system. I would like isolate brakeing from suspension and test them independently. It looks as though there is a single suspension takeoff from the secondary air tank through a Haldex valve. I will look into supporting the vehicle and then 'blocking' the suspension takeoff.

(It also indicates there is a filter in that valve that needs to be checked.)

Skip426 · 05-24-2023, 10:39 AM

Dan ; I have these pdfs on Spartan air system dated 2001 .

If you notice differences between the pdfs and your coach please contact Spartan with your chassis serial number , for info linked to your chassis by serial number .
If Spartan is anything like Freightliner , things change about as often as I change my socks .

prafersno · 05-29-2023, 03:41 PM

How much does the coach rise when inflated (or drop when dumped)?

Asking in relation to a Spartan MM GT

Do you dump the suspension for camp setup then level with jacks?

Rob_M · 05-29-2023, 09:03 PM

Quote:

Originally Posted by prafersno

(1) How much does the coach rise when inflated (or drop when dumped)?

(2) Do you dump the suspension for camp setup then level with jacks?

(1) would have to measure but at least 4”.

(2) Yes. As soon as you start to deploy jacks it dumps air automatically. I usually dump manually and if it’s level enough I don’t deploy jacks at all.

2002 Spartan MM with 3 jack leveling.

Ray,IN · 05-30-2023, 03:59 AM

The dump valve is actuated by two methods, using the auto-level function automatically dumps the air springs then deploys the leveling system; if you push the dump button it dumps the air springs but does not deploy the leveling system, requiring manual leveling with my HWH 610 system.

The front air springs move more(~4") than the rear due the rear Reyco Granning 610AR suspension module design. It only has limited travel, 2.3"-2.8" up/down.

Even though we all have a Spartan MM chassis, they are not configured the same. The front suspension, while still Reyco Granning brand, it differs with weight rating and solid axle or IFS.
source: https://reycogranning.com/sales-service-literature/

For instance my chassis has the HWH 610 central-ground 4-jack leveling system.
The coach mfgr. who built RobM's coach chose to use the HWH 3-jack leveling system.

Tha_Rooster · 06-02-2023, 07:13 AM

Quote:

Originally Posted by dansawyer

Whoops. I have totally crossed terms. My bad.
I should have said air ride adjustors. I should have said the air ride adjustors are mechanical.

(You are correct about the levelors. They are hydraulic.)
This whole thread is about air ride adjustors. I am chasing an air leak and an rv list, the drivers side is high.

There is no way one side could be high or low with out it being ride height valve not being adjusted correct or a bad leaky air bag. In my opinion. With that said you probably only have 1 valve in front and 2 in rear at-least my MM is that way. You have a 2002 air bags if original have to be severely cracked.