air leaking, what is this?

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air leaking, what is this?

July 11, 2019, 11:32:33 am

Air is leaking from the fitting in the first picture where my index finger is touching. Just jumped under, after blocking, to get a quick picture of the leak to asses. Fitting is on part of the lines going to the front air tank. Can't get eyes on yet, but feels like it is coming out between the cap and the thread. Is this normal? What is the part? (appears to be an air pressure gauge) Do I need to replace or can it be fixed? The coach airs up fine and have not had any problem keeping air pressure.

Any and all suggestions would be appreciated.
Thanks Tommy

Re: air leaking, what is this?

Reply #1 – July 11, 2019, 11:37:31 am

That is an air pressure regulator, just like what you will find on a typical air home shop compressor. This is probably either for the step cover or the drop down step. Or if it is up front, for the front ~~brake tanks~~ air suspension. I purchased a new one from Napa, but I know people have gotten them from Home Depot or Lowes as well.
Don

Re: air leaking, what is this?

Reply #2 – July 11, 2019, 11:46:28 am

Thanks Don, So if it is leaking it needs to be replaced?

On an air compressor it has a dial that you can adjust the kick off pSI, what should it be set to?

Re: air leaking, what is this?

Reply #3 – July 11, 2019, 12:12:18 pm

My regulator is set to 60 psi.

Re: air leaking, what is this?

Reply #4 – July 11, 2019, 12:19:37 pm

It depends on what the regulator is controlling, but Mike posted that info in this thread. Air Pressure
From Mike;

Quote

The last time I replaced mine the step cover and step regulators are set at #60.
This can vary with different coaches and how the Noreg shuttle valves are set up.
The one that feeds the air bags is set at #45 IIRC I need to go look this up in my notes tomorrow.

I don't have the drop down step anymore, but for the step cover I used 55 PSI and it seems to work well. For the front air springs, 45 psi seems a little low, but I bow to Mike's info, since he is usually spot on. I am not clear on how the regulator can bet set to 45 PSI, yet to raise the front high enough to put the 12" frame blocks in for safely working underneath, the front tanks needs to be up around 100 PSI.
Don

Quote from: Tommy D – July 11, 2019, 11:46:28 am

Thanks Don, So if it is leaking it needs to be replaced?

On an air compressor it has a dial that you can adjust the kick off pSI, what should it be set to?

Re: air leaking, what is this?

Reply #5 – July 11, 2019, 03:39:25 pm

Quote from: Don & Tys – July 11, 2019, 12:19:37 pm

For the front air springs, 45 psi seems a little low, but I bow to Mike's info, since he is usually spot on. I am not clear on how the regulator can bet set to 45 PSI, yet to raise the front high enough to put the 12" frame blocks in for safely working underneath, the front tanks needs to be up around 100 PSI.

Don,

I have never understood the purpose of the pressure regulator in the air supply line going to the front 6-pack.

Yes, I have heard the "conventional wisdom" bandied about this Forum: "The regulator keeps the front end of the coach from raising up faster than the rear end" or some variation on that statement. This concept has been debated here before, so I won't rehash the old arguments. Nor am I brave enough to remove the regulator from my coach, even if it seems to be of dubious value...at least to me.

My front 6-pack pressure regulator was totally inoperative when we bought our coach. I replaced it with one from Home Depot. When I searched on the Forum for the "proper" pressure setting, I came up with reference to "60 psi" in several threads, so that is where my regulator is set. Is this correct (for my '93 U280)? Who knows... Everything in the air suspension system on our coach seems to work fine. I have no problem raising our coach fully to insert my safety stands.

The protection valves on the front and rear air tanks are supposed to remain closed until approximately 60 psi, at which point they open and allow air flow to the 6-pack manifolds. The unregulated rear 6-pack, then, can see normal operating pressures anywhere from 60 psi up to the pressure at which the engine air compressor unloads (usually around 120 psi).

However, on my coach the air from the front tank, once it gets past the 60 psi protection valve, immediately encounters the pressure regulator. A simple pressure regulator, as I understand them, maintains the downstream pressure at (or below) the set value, depending on the upstream pressure. So, with the regulator set to 60, or 45, or whatever pressure - that is the highest pressure the front 6-pack will ever see. If that is indeed the case, then 45 psi seems very low to me. Actually, even 60 psi sounds like it would be barely adequate to operate the front suspension.

The HWH Leveling System Text Book, Page 3 says this on the subject of operating air pressure:

"Although it may vary between different vehicles, it normally takes at least 60 psi to start lifting a vehicle. Most vehicles will require 90 psi to obtain maximum lift. Some may require up to 130 psi to obtain maximum lift." (link to .pdf copy of that page below)

Like I said - the intended purpose of that regulator is a big question mark to me. Perhaps someone else can explain it to the class...

Re: air leaking, what is this?

Reply #6 – July 11, 2019, 03:44:06 pm

Don,

On our coach the ride height air is set at about #45 and comes off before the protection valve. The air that feeds the raise side of our manifold is what ever the front tank pressure is and comes off behind the protection valve. In other words we have 2 air sources to our front 6 pack. With that being said other coaches may or may not be set up like our coach is.

Mike

Re: air leaking, what is this?

Reply #7 – July 12, 2019, 02:33:53 am

Tommy,

Last week I bought a front six pack regulator from Grainger, #4ZM08. Actually, I bought two; one to replace the leaking one, and one to carry on-board for a spare, since it's the same regulator used for the step and step well cover.

All,

The reasons I've read here, on the forum, for having a regulator ahead of the front six pack all seem to have merit. That being said, I'll throw another one out there: To limit the load on the shock bushings when the front is raised to maximum height, manually, or via the HWH computer. Once sufficient air pressure is reached, it's the shocks being fully extended that limit any further increase in height. Any additional lift pressures would be applied to the shocks/bushings, possibly causing premature wear to the bushings.

Theory: IMO, the ideal pressure setting for the front HWH regulator should be based on the front axle weight rating. Likely that FT and/or HWH has these pressures on record somewhere? Without that information, one should be able to figure it out the old fashioned way: Trial and error

. With the coach loaded for travel, set the regulator for 50 PSI (Safety Blocks In Place while you're under the coach) and manually raise the front as far as it will go. If it doesn't top out, increase the pressure 10 PSI. Repeat if needed. This approach is pretty coarse (could use 5 PSI increments, or whatever) but should get the job done. Also note, on our coach, since the front ride height valve is supplied at tank pressure, behind the protection valves, the regulator setting does not effect Travel Mode.

Disclaimer: The above is my opinion, only. I believe it to be sound but, USE AT YOUR OWN RISK.

Greg

Re: air leaking, what is this?

Reply #8 – July 12, 2019, 08:27:11 am

Greg,

Your "regulator" theory seems as reasonable as any other I have heard. But then I wonder, If this was the intention of the Foretravel engineers, why not fit a regulator to the supply air line for both 6-packs? Is the suspension design not basically the same at both ends? (I don't know for sure) Of course, the rear end of the coach is somewhat heavier, but enough so that that only a unregulated air pressure supply will suffice?

Re: air leaking, what is this?

Reply #9 – July 12, 2019, 10:33:42 am

Chuck,

As you say, the rear end is heavier, much heavier. The rear is regulated to 120 PSI +/- by the compressor unloader. Close enough for four air springs supporting 20k Lbs? Maybe.

Re: air leaking, what is this?

Reply #10 – July 12, 2019, 10:50:10 am

Greg,

Guess that makes perfect sense. If the air pressure required to lift a given weight follows a linear relationship, then twice the weight would require twice the pressure. So on my coach, where the actual front axle load is almost exactly half the rear axel load (verified by the Escapees 4-Corner weigh program), then if 60 psi is just sufficient to fully raise the front it would follow that 120 psi is required at the rear.

I LIKE IT! Your Front 6-Pack Pressure Regulator Theory has now risen to the top of the list...at least for me. Thanx for bringing it up!

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air leaking, what is this?

July 11, 2019, 11:32:33 am

Re: air leaking, what is this?

Reply #1 – July 11, 2019, 11:37:31 am

Re: air leaking, what is this?

Reply #2 – July 11, 2019, 11:46:28 am

Re: air leaking, what is this?

Reply #3 – July 11, 2019, 12:12:18 pm

Re: air leaking, what is this?

Reply #4 – July 11, 2019, 12:19:37 pm

Re: air leaking, what is this?

Reply #5 – July 11, 2019, 03:39:25 pm

Re: air leaking, what is this?

Reply #6 – July 11, 2019, 03:44:06 pm

Re: air leaking, what is this?

Reply #7 – July 12, 2019, 02:33:53 am

Re: air leaking, what is this?

Reply #8 – July 12, 2019, 08:27:11 am

Re: air leaking, what is this?

Reply #9 – July 12, 2019, 10:33:42 am

Re: air leaking, what is this?

Reply #10 – July 12, 2019, 10:50:10 am

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