Thinking about adding an "On board" air compressor.

[FIRE UP]

Gents,
As we all know, air systems are air systems. Some are prone to leak and some are, well, they just don't show the PSI drop so quick. Now, All the later fire trucks we received starting from about 2002 and on, came with an "On board" electric air compressor. These compressors were small but, fairly powerful. They were tied into the air system and would, upon demand, fire up and keep the air systems in our trucks, topped off so that when we jumped in our rigs for a response, we wouldn't have to tell dispatch: " Delayed response due to low air".

Well, my rig, an '04 Itasca Horizon 36GD with the 330 C-7 CAT, does have one or some, air leaks. They are small but, they or it, is there. I've never done a time/PSI test to tell just how much is lost, after parking with a full system to determine the rate of loss. I know, I know, I know, I should get under there and FIND, the leaks! Yep, I agree. But, having experience with air systems on Fire trucks etc. for well over 35 years, guess what, they'll be back, just like Arnold.

If I had an estimate, I'd say ours looses around 9 lbs. per day. That's based on the last time I ran the coach 'cause I had to move out from under the cover to raise the TV antenna for testing. And, I'm assuming I parked it with a full system. And today, I pulled it out again for more testing and had 35 psi at startup. So, in a 10 day period, I lost 90 psi or, about 9 lbs. a day.

Yes, maybe I'll get under there and start spraying some connections etc. with the ole' soap and water solution to see what's what. But, in the mean time, I'm thinking of adding a compressor that will, just like our Fire trucks, keep things topped off. Now, yes, I know, I'm not in a hurry and don't have to "BOLT" out of the RV parking spot the minute I start the thing up so, I can wait for it to build pressure.

This is just something I'm toying with. I think it would be a fun little project and, I really don't think it would be that hard. I never did see how the ones in the fire trucks were tied into the main air system. It can't be all that hard. A "TEE" in the main supply line, a check valve or two, and wire it, that should be it. Getting the components is the easy part. Setting it up, well, that's the challenge.

And, before anyone here get's all hot and bothered and says: "What about the middle of the night and you're in a campground/RV park, you'll wake up the entire campground". Well, I got that covered too. There will be two provisions for that. One, it will be muffled in one way or another and, two, I can always put a switch on the electric side of it so it's out of commission at my command. One that I'm thinking about is this one:

Viair 100C Silver Utility Air Compressor for Air Suspension Air Horns | eBay

It's capable of 130 PSI which, is just above what my engine one cuts out at. But, that's just a start. I'll keep looking to see what might work in that application. I don't want the monster one like the Sears I carry as an auxiliary air supply for tires etc. I want a compact but, strong one. So, what does anyone think? Again, this is just on the drawing board for now.
Scott

[joeplazek]

Originally Posted by FIRE UP

Gents,
As we all know, air systems are air systems. Some are prone to leak and some are, well, they just don't show the PSI drop so quick. Now, All the later fire trucks we received starting from about 2002 and on, came with an "On board" electric air compressor. These compressors were small but, fairly powerful. They were tied into the air system and would, upon demand, fire up and keep the air systems in our trucks, topped off so that when we jumped in our rigs for a response, we wouldn't have to tell dispatch: " Delayed response due to low air".

Well, my rig, an '04 Itasca Horizon 36GD with the 330 C-7 CAT, does have one or some, air leaks. They are small but, they or it, is there. I've never done a time/PSI test to tell just how much is lost, after parking with a full system to determine the rate of loss. I know, I know, I know, I should get under there and FIND, the leaks! Yep, I agree. But, having experience with air systems on Fire trucks etc. for well over 35 years, guess what, they'll be back, just like Arnold.

If I had an estimate, I'd say ours looses around 9 lbs. per day. That's based on the last time I ran the coach 'cause I had to move out from under the cover to raise the TV antenna for testing. And, I'm assuming I parked it with a full system. And today, I pulled it out again for more testing and had 35 psi at startup. So, in a 10 day period, I lost 90 psi or, about 9 lbs. a day.

Yes, maybe I'll get under there and start spraying some connections etc. with the ole' soap and water solution to see what's what. But, in the mean time, I'm thinking of adding a compressor that will, just like our Fire trucks, keep things topped off. Now, yes, I know, I'm not in a hurry and don't have to "BOLT" out of the RV parking spot the minute I start the thing up so, I can wait for it to build pressure.

This is just something I'm toying with. I think it would be a fun little project and, I really don't think it would be that hard. I never did see how the ones in the fire trucks were tied into the main air system. It can't be all that hard. A "TEE" in the main supply line, a check valve or two, and wire it, that should be it. Getting the components is the easy part. Setting it up, well, that's the challenge.

And, before anyone here get's all hot and bothered and says: "What about the middle of the night and you're in a campground/RV park, you'll wake up the entire campground". Well, I got that covered too. There will be two provisions for that. One, it will be muffled in one way or another and, two, I can always put a switch on the electric side of it so it's out of commission at my command. One that I'm thinking about is this one:

Viair 100C Silver Utility Air Compressor for Air Suspension Air Horns | eBay

It's capable of 130 PSI which, is just above what my engine one cuts out at. But, that's just a start. I'll keep looking to see what might work in that application. I don't want the monster one like the Sears I carry as an auxiliary air supply for tires etc. I want a compact but, strong one. So, what does anyone think? Again, this is just on the drawing board for now.
Scott

Neat idea. BUT I don't think 9lbs a day is abnormal and is anything to worry about.

[Tony Lee]

Any changes or additions to the rig's air system might invalidate the DOT approvals, especially since it involves the brakes.

[njs42]

VIAIR makes a good product. Good choice.

[1ciderdog]

I understand your thought on this but personally I'd spend the time first to make sure the present on board system is functioning correctly.

[FIRE UP]

Originally Posted by joeplazek

Neat idea. BUT I don't think 9lbs a day is abnormal and is anything to worry about.

joeplazek,
Well Sir, I'm not really "worried" about it. In fact, it's been like this since we purchased the rig, back in May of 2011. And, as stated, we're in no hurry if we're camped at anyplace and have wait for a minute or two for it to build air prior to our departure of the campsite. It's just something I'm toying with.

Originally Posted by Tony Lee

Any changes or additions to the rig's air system might invalidate the DOT approvals, especially since it involves the brakes.

Tony Lee,
While I appreciate your thoughts and concerns, as stated in my original post, starting around '02, all of our newly received fire trucks had this addition to the air system. Besides, I'm not too worried about keeping in what "DOT" thinks is approved or not. It's an inevitability that air systems will leak. Just how much, well, that's individual for each and every one of them. Thanks again.

Originally Posted by njs42

VIAIR makes a good product. Good choice.

njs42,
VAIR, is just one that I was looking at. The ones we had/have on all the F-trucks were made by "Kussmaul". This one is the one in particular but, those are on the higher end and, I don't think the issue of my air loss warrants that kind of expenditure. So, I'm just looking around right now.

Originally Posted by 1ciderdog

I understand your thought on this but personally I'd spend the time first to make sure the present on board system is functioning correctly.

1ciderdog,
Chances are, I will cruise around under the coach with a bottle of soap/water spray and hit all the connections, lines, air dryer and anything else that looks like it's even remotely tied to the air system before I goof around and take my addition seriously. I mean, who wouldn't want a perfectly sealed air system? It's not that much of an air leak which means it might be pretty tough to find. As far as my regular air system working properly, yep, it works perfect. I've bled it all the way down to "0" and timed the build up 'till compressor shut down and, it, at a 1000 rpm, only took a minute or two, 'can't remember, it was a while ago.

And, the cut in pressure is within the correct limit as well at the cut off pressure. When I bleed the tanks, I've never, ever got any moisture out of any of them. My brakes work flawlessly as well as the parking brakes. The only thing I've not done, is change the air dryer filter. Yep, got to get under there and do that, SOON.

Thanks to all for responding to my inquiry. Again, this is simply on the drawing board right now and I was just wondering about thoughts and, if possible, a response from someone that's done it.
Scott

[rgvtexan]

Aren't you going to dump the air to level when parked? You won't need it again till you are ready to travel. And you no longer need to respond to the bells and gongs. lol

[ShapeShifter]

I like this idea, but for a different reason. I've not yet taken any time to look into the feasibility.

Originally Posted by rgvtexan

Aren't you going to dump the air to level when parked? You won't need it again till you are ready to travel. And you no longer need to respond to the bells and gongs. lol

Exactly, the air tanks are dumped when at camp. The issue, for me at least, is when it's time to leave. Having a coach built by Monaco, their recommendation is that the slides should only be operated when the jacks are retracted and the suspension is fully up to pressure. This means that mid-way through the tear down process, I have to start the engine, and run it long enough to build up air while I'm raising the jacks. Then I shut it down, pull in the slides, and do the final packing away of stuff. Then I can finally start the engine again and pull out.

Out of courtesy to the campground neighbors, it would be nice to inflate the suspension with a quiet electric compressor, rather than have to run the engine and subject the neighbors to more noise and diesel exhaust smell than is necessary. But unlike the desire to keep the air topped off, which doesn't require much air volume, to get my application satisfied in a reasonable time might require a bigger compressor, which might not be desirable from a cost, weight, or noise standpoint.

I don't want to hijack the tread, but would be interested in any comments related to either of these applications.

As for tying into the system, it may not be necessary to modify the existing system, which may help allay DOT concerns. My coach (and I assume most others) has an air quick connect stud up front, which can be used by a tow truck to air up and release the brakes. I have used this fitting with my big stationary home compressor to quickly air up the system and it works well. So rather than modify the system, perhaps the auxiliary compressor could attach here with the appropriate quick connect? I would probably add a check valve directly to the quick connect with a hard fitting, then transition to a flexible hose. That way if the hose deteriorates and leaks, it is less likely to drain the system.

Using this method would put the air directly into the tank, so the compressor should probably have an air filter/desiccant dryer like the engine air system.

Thoughts on any of this?

[FIRE UP]

Originally Posted by rgvtexan

Aren't you going to dump the air to level when parked? You won't need it again till you are ready to travel. And you no longer need to respond to the bells and gongs. lol

rgvtexan,
Well Sir, to answer your question, yes I do dump the air BEFORE leveling. But, just for yours and ShapeShifters information, it is THE BAGS ONLY that dump, not the air tanks. I still have full tanks when I dump the air bags when the leveling system is in play. I don't know how other manufacturers do it, but, on this Freightliner Evolution Chassis we have, that's the way it works. So, if and when I build this "add on" system, it will only top off the air tanks, not the bags as we sit in camp.

Originally Posted by ShapeShifter

I like this idea, but for a different reason. I've not yet taken any time to look into the feasibility.


Exactly, the air tanks are dumped when at camp. As stated above, my tanks are not dumped in prep for leveling. The issue, for me at least, is when it's time to leave. Having a coach built by Monaco, their recommendation is that the slides should only be operated when the jacks are retracted and the suspension is fully up to pressure. This means that mid-way through the tear down process, I have to start the engine, and run it long enough to build up air while I'm raising the jacks. Then I shut it down, pull in the slides, and do the final packing away of stuff. Then I can finally start the engine again and pull out.

Out of courtesy to the campground neighbors, it would be nice to inflate the suspension with a quiet electric compressor, rather than have to run the engine and subject the neighbors to more noise and diesel exhaust smell than is necessary. But unlike the desire to keep the air topped off, which doesn't require much air volume, to get my application satisfied in a reasonable time might require a bigger compressor, which might not be desirable from a cost, weight, or noise standpoint.

I don't want to hijack the tread, but would be interested in any comments related to either of these applications.

As for tying into the system, it may not be necessary to modify the existing system, which may help allay DOT concerns. My coach (and I assume most others) has an air quick connect stud up front, which can be used by a tow truck to air up and release the brakes. Well, again, on ours, yes we have that air chuck, but, it is in no way tied into the brake system on our coach. I built a double male adapter for that just to see if I could fill an empty system, NOPE, it ain't happening. Ours has a check valve in it that does not allow any air to infiltrate at that point. On ours, you CANNOT fill the system to allow tow trucks to release the brakes. It simply won't work. I have used this fitting with my big stationary home compressor to quickly air up the system and it works well. So rather than modify the system, perhaps the auxiliary compressor could attach here with the appropriate quick connect? I would probably add a check valve directly to the quick connect with a hard fitting, then transition to a flexible hose. That way if the hose deteriorates and leaks, it is less likely to drain the system.

Using this method would put the air directly into the tank, so the compressor should probably have an air filter/desiccant dryer like the engine air system.
I'm glad your system works in that manor for you. I've tested this and the only way, to fill our tanks enough to release the air parking brake is via a shrader valve, located on the bottom of the air dryer. I had to keep our air system with enough air to keep the brakes from "auto applying" while I had the left rear duals, hub and axle off to replace a hub seal on our rig. And, that hub was apart for a few days while the seal was being shipped to our home. So, I didn't want the brakes being applied with no drum on there and, this rig loosing air.
Thoughts on any of this?

As stated above, our tanks do not dump for leveling the coach, just the bags do. So, in your situation, if your tanks completely empty for leveling, then yes, a small "Top off" compressor like I'm thinking of will be severely over worked and be on for hours. You would need a large volume, high CFM electric one in order to foot the bill of filling an entire system. And, I thank you for considering your neighbors when running your rig. I know that you, and many other Diesel rigs must run in order for certain things to be accomplished. But, to be considerate, is very much appreciated.

I only run ours for the time needed to bring up the jacks and fill the bags. Then it's "In Drive" and we're out of there. As for you needing an electronic air compressor for your intensions, yes, it can be done and, with not too much cost. I've built units like that for next to nothing. And yes, it would take up a bit more room than one of those tiny things I'm thinking about. But, the CFM on the ones I've built are comparable to the home units.
Scott

[1ciderdog]

Originally Posted by FIRE UP

rgvtexan,

I only run ours for the time needed to bring up the jacks and fill the bags. Then it's "In Drive" and we're out of there. As for you needing an electronic air compressor for your intensions, yes, it can be done and, with not too much cost. I've built units like that for next to nothing. And yes, it would take up a bit more room than one of those tiny things I'm thinking about. But, the CFM on the ones I've built are comparable to the home units.
Scott

Fire up
My Journey is the same year as your Itasca and my jacks come up using springs. I don't need to run the engine to retract jacks but do run the engine to extend the jacks and to extend/retract the slides and/or fill the air tanks. That was recommended to me by a tech at Forest City.

A completely different question: How do you get the multiple quotes in replies?

[bluepill]

A thought: One thing that bothers me on my rig (being a rear radiator) is having to run the engine to air up the tanks after staying a week or more at a CG that has dirt or dusty gravel pads. It ends up blowing the dust/dirt out the back and all over my toad or someone else's RV or toad. It would be nice to just start the engine and pull straight out of the site. Now I have 2 reasons to buy a compressor.

I don't need the engine running to retract the slides - I can leave the MH on shore power and press the emergency start switch to connect the chassis battery to the converter/charger to keep the voltage up.

[ShapeShifter]

Thanks for your detailed response!

Originally Posted by FIRE UP

Well, again, on ours, yes we have that air chuck, but, it is in no way tied into the brake system on our coach. I built a double male adapter for that just to see if I could fill an empty system, NOPE, it ain't happening. Ours has a check valve in it that does not allow any air to infiltrate at that point. On ours, you CANNOT fill the system to allow tow trucks to release the brakes. It simply won't work.

It doesn't sound like we're talking about the same fitting. Up front, behind the generator slide, I have three air fittings: a male quick connect stud (input) for charging the brakes when towing, a female quick connect (output) to attach a hose for airing tires or other uses, and a valve to drain the front air tank (there is a similar valve on the hitch for the rear bags.)

Sounds like you don't have the male input fitting, and the one you're describing sounds like the female output for accessories. As for the tank drains, you might have lanyards to pull, if I recall the typical Freightliner setup.

it is THE BAGS ONLY that dump, not the air tanks. I still have full tanks when I dump the air bags when the leveling system is in play.

I wish mine worked the same way. :( I have a momentary switch I have to hold while the air bags are dumped. But it doesn't just dump the bags, it has to dump the whole air system. Just using the dump switch, it can take forever, because if you let go of the switch before the whole air is dumped, the bags will simply inflate again. So to speed things up, I fan the brakes or half-press the parking brake knob to bleed of the main air pressure first, while holding the dump switch to bleed the bags. It sounds like you have a MUCH better system. I have often wondered if it would be practical to add some sort of valve that could be closed when dumping the air bags so that the whole system doesn't need to be drained. Not only would that speed up/simplify dumping, but it would greatly shorten the time to build up air pressure, and lessen my concern about making noise.

So, in your situation, if your tanks completely empty for leveling, then yes, a small "Top off" compressor like I'm thinking of will be severely over worked and be on for hours. You would need a large volume, high CFM electric one in order to foot the bill of filling an entire system.

I agree. I looked at the specs of the compressor you posted, and all of the others by the same company, and had decided that their air volumes and duty cycles are far too low for it to be practical. It would take a much more robust higher capacity (120 volt?) compressor (which would likely be too noisy to be worth it.) Or it would need a very quiet 12 volt system that could fill a large air tank over a period of hours, which could then be dumped into the coach system relatively quickly. Again, not really practical.

[TRAILERKING]

Just fix the leaks............if you have leaks. It's just that easy.

[KIX]

The system you describe was factory installed on a friends 1988 Bluebird. Still works. The suspension can be inflated without regard to the main engine air compressor.