I like having an air compressor around to fill tires, run some air tools and maybe pressurize the air tanks on the coach before starting to save on idle time. I borrowed a friends portable pancake compressor C2005 6-Gallon Portable Electric Air Compressor-C2005 at The Home Depot (http://www.homedepot.com/h_d1/N-5yc1v/R-202529941/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053) and plugged it into my airline using a double-ended adaptor and was able to pressurize my tanks. I was so pleased with this that I was ready to head off and drop the coin at HD. Before I did though I remembered that I'd have to store it somewhere. Hummm.... Didn't really want to give up the storage space. After thinking on it I realized that I already had air tanks and I just needed an air pump. A pump would take up much less space and I could mount it somewhere out of the way on a switch.
After more thought remembered that using the pancake compressor I was pumping wet air into my tanks. Probably not a good idea. But wait I have a dryer on the engine! I could mount the pump in or close to the engine bay then run a tee into the air line before the dryer. Does the engine need to be running for the Haldex dryer to work? If so I guess I could add a separate air dryer.
My main worry is that I'd be adding an additional point of failure to the air system. I would put a one way valve at the tee where I'd be joining the existing air line. Would I need to put a one way valve to keep air from feeding back into the engine compressor. Seems like there would already be one there if so.
Has anyone done something like this? Is there anything else I need to be aware of? Should I just find room for the pancake air compressor? Or just trash the whole idea?
Here is the compressor I'm considering. Amazon.com: Viair 450C 12 Volt IG Series Air Compressor Kit (CE): Electronics (http://www.amazon.com/Viair-450C-Volt-Air-Compressor/dp/B002OH319O/ref=sr_1_1?ie=UTF8&qid=1322778902&sr=8-1) These are generally used by those morons fine fellows who like to bounce their cars up and down. They are pretty heavy duty and are rated at a 100% duty cycle.
All comments and suggestions appreciated!
see ya
ken
Ken,
Understand where you are coming from, but DON'T DO IT.
By "T-ing" into the coach air system with a potential failure point would give DOT the shakes. And I can assure you the pancake compressor you are looking at would NOT be DOT approved for your air brake system.
And, if you do decide to air up the coach air system with a supplemental compressor, verify that you have a serious air dryer that removes both oil and moisture so that you don't contaminate your air suspension and air brakes.
Bottom line is that starting the diesel engine, going to high idle after 20 seconds or so should bring air pressure up enough to move about the same time as the temperature gauge starts to move. That is when you want to start driving anyway-- assuming you are not camping on a freeway entrance.
Brett
Ken,
I use a contractor's twin tank compressor I bought off Craig's list for $55. 135 psi pretty quickly. I have it plugged into the outlet in the cargo compartment and use it to air my tires and change them with an impact if necessary. I bought it because it took forever to inflate the tires to 110 psi with the engine compressor. It will remove a couple of lug nuts before I have to wait 30 seconds or so for it to build pressure again. There is a lot of room forward under the nose to install an extra tank if necessary, in fact, you could install the compressor there also.
So, here is the problem I see with the Amazon compressor. I reading the specs, there is no mention of the CFM or cubic feet per minute. The amount of current it draws is no where near as important as how fast it will build pressure. The duty cycle is just more fluff thrown in. They did not include the CFM number as it would disqualify it from many buyers. It is probably made in China so chances are, it could be found on ebay or just using Google search for much less. Having been in import/export, I would expect the seller has marked it up several hundred percent.
You could stick a regulator/dryer after the tank like painters do to keep moisture out of the spray gun and what ever they are painting.
The most important thing for me was the compressor to supply good amount of high pressure air in a short time and not take up much space doing it. The twin tank does a great job in all respects. A bit noisy when running but thats the only drawback I can see.
Pierce
Ken,
Brett says it all with the "don't use it to bring pressure up". It should only take a few seconds to bring the pressure up with the main engine. If you are down to zero, you have a leak and should check it out. I can sit for weeks and still have 60 psi in the tanks with the exact same rig so one to two minutes does it for me.
Pierce
And a little more info: This is the kind I bought. It has four feet with the compressor/motor down low for stability and stows nicely against a wall. Has never moved since I installed it. See at: http://www.ebay.com/itm/AIR-COMPRESSOR-4-GALLON-TWIN-TANK-2-HP-MOTOR-WEN-/130547160413#vi-content (http://www.ebay.com/itm/AIR-COMPRESSOR-4-GALLON-TWIN-TANK-2-HP-MOTOR-WEN-/130547160413#vi-content)
Pierce
One of the reasons we carried a Power Tank to fill tires was that it was not always convenient to fill or top off a tire just before driving. Too often it was raining or some other conditions existed that made this a less than desirable time to put air in our tires. A separate compressor or air tank allowed (we had the separate air tank) us to address tire issues anytime and any place. I am not trying to be a smart ass here, just trying to help others to see that a separate air source has some advantages.
George,
Understand the desire for a separate compressor for airing the tires. And, I guess that is OK, but the DRY air from the on-board air system is a LOT better for the tires, unless you have a quality air dryer on your portable compressor.
Brett
@Brett I wasn't clear in my post that I wasn't planning to use the pancake air compressor inline . Just to bring the coach tanks up then disconnect. Have to agree that it's not a good idea to mess with the stock coach air system. Setting myself up for some DOT liabilities there.
@Pierce The Viair website says it does 1.66 cfm @ 0 psi on 12VDC. They also claim 0-105psi time for a 2.5 gallon tank of 1 min 55 sec. Let's call it 2 minutes. :) Brett has already talked me out of going this route so point is mute now. You have convinced me that a separate compressor is the way to go.
@george I've looked at the pressure pros but am put off by the price. I can buy 3 or 4 compressors for the same price! The size, portability, & quality are certainly attractive. I could also use it in my Xterra. There where a couple of times in Moab this fall that I'd have liked to lower the tire pressure while 4wheeling. I know "Buy the best & cry once" which I've modified for my on personal use to "Buy the (2nd)best & cry once"!
I must have an air leak somewhere. My air is at 10lbs after 3 days and it takes 10 to 15 minutes to build air at idle. Unfortunately I don't have the fast idle option on my cruise. Either that or I don't know how to use it! I've tried starting the engine, turn on the cruise, hit Set, then hit the Accl a couple of times and nothing. :( When I get a break in the weather I'll start looking for leaks.
I'll have to think on this some more. I may have talked myself out of the compressor and into the PressurePro. I'll keep an eye on Craigslist for a few days and see if fate dumps a too good of a deal to pass up my way.
Thanks everyone for the advise and keeping me from doing something stupid!
see ya
ken
I am with George and the Power Tank, I got the larger one in case I needed it on a job for some air tools.
Have to say, once you get comfy with the Power Tank, you have no need for an on board compressor, Also only use it on the tires, not the air system.
Fills tires quick once you figure it out, like most things, there is a learning curve.
Ken,
No, we don't have the fast idle feature. Bummer. Once it's idling smoothly, I just use my foot to bring it up to 1000-1200 RPM. Builds air a lot quicker.
You do have a leak. Pretty easy to find but not when you're freezing. ???
We've all done lots of stupid things. Just ask my wife. But no stupid questions on the forum.
Pierce
Ken,
On our coach, the air brake systems drop to about 10 psi after a couple of days as well. That is well within specifications for air brake systems, but FT coaches often have better retention. Pressure seems to drop more quickly in cold weather. On one our trips in subfreezing weather, the pressure on one gauge would sometimes drop below 70 psi while the engine was at idle. On our next "service trip," Wayne at FOT discovered and fix that leak while he was working on our generator and front axle.
Someone report that an air leak increased fuel consumption because of added compressor run time. A tight air system has advantages.
Our air bags will stay inflated and hold the coach level for weeks with the leveling system turned off.
Our cruise control does work to bring up the idle speed. However, even at low idle, the pressure comes up reasonably well. I use the time while pressure builds to open blinds, check doors, walk around the coach, check bays, check lights, check the little door for utility lines, check the awnings, etc.
According to tire charts, cold pressure in our tires doesn't ever need to exceed 95 psi. With a bit of patience, I easily air the tires to appropriate pressures. I wait until I hear the dryer "pop off," then apply air to the tire. My understanding is that the system is at maximum pressure when the dryer unloads. I have a Milton chuck with a built in gauge which facilitates the process.
@Pierce I remember reading in my manual that fast idle was an option on the DDEC cruise control. Bummer my stupid original purchaser didn't spring for it! :) Guess I'll be using the manual fast idle option. Hummm... If I cut a broom stick down to just the right size... (just kidding!)
@J.D. FOT checked out my coach for leaks back in June and said it was within specs. I can't remember if it was leaking down then as fast as it is now. I do plan to put the frame blocks I had made up a couple of weeks ago to use and check for any egregious leaks when the weather lets up.
see ya
ken
We have a Viair compressor that we use to air up our Jeep & motorhome tires directly from compressor without a tank. Viair has open & closed frame styles. Open cannot be mounted where they can get wet, but will run much cooler and longer than closed frames, which can be mounted under a Jeep and can get wet, but they are supposed to run in short bursts as they don't have outside air to cool them.
Also our Viair did not come with a pressure switch to shut if off when I closed my air hose chuck, so I added a pressure switch, but although it was a high amp switch, it only lasted a year, probably because of the high amp draw of a motor running against a closed off hose, just before shutoff. I did not replace the pressure switch and I now use an 'open' air hose chuck which does not close off when it is taken off a tire stem. Compressor continues to run and air is dumped from open chuck.
Ken,
A reserve air tank is a great accessory but takes a bit of work to install. No matter what the air pressure, push the "reserve" button and it brings the pressure up to go in about 5 seconds. Automatically refills while driving. Makes one lazy about finding leaks though.
Pierce
That sounds like a great idea! Any links or posts you know of that explain howntobgo about this?
Thanks,
Don
Don,
The reserve air tank was created out of necessity in the fire service. While each apparatus is started at least once a day and checked, air leaks may occur that would drop the pressure below the limit to be able to release the parking brake. You can image the town burning and the fire truck sitting in the station waiting for air pressure to build so they could respond to the call.
So an extra tank is installed in the system with tubing/hoses leading up to a control next to the driver. This tank is kept in "reserve" and is not used in normal operation. In the rare event that the service brake air supply has fallen below the threshold pressure (somewhere around 55 to 60 psi) and the parking brake (anchorloks as we called them)(see Haldex Anchorlock or Anchorlok) cannot be released, the reserve button/valve is pushed releasing the reserve tank pressure into the main system. This quickly builds pressure above the parking brake release pressure and away you go. The reserve hand button/valve is spring loaded and returns to the normal position and a one way valve allows the reserve tank to fill but not flow back into the main system. This is a very simple mechanical setup with no electrical power required. A buzzer does sound if the normal system pressure falls below a preset limit alerting the driver to a low pressure malfunction.
This could easily be fitted to any vehicle with air brakes. I am not sure if the retrofit would have to be inspected to be legal. Could cause a lot of legal problems in case of an accident if not approved.
Here is a good PDF with lots of color diagrams, etc. for all operators of vehicles with air brakes: http://www.community.gov.yk.ca/pdf/airbrake_manual_english.pdf (http://www.community.gov.yk.ca/pdf/airbrake_manual_english.pdf)
This is a check list some departments use for air brakes. We did not have a air supply line to the station compressor. We also had no air dryer so had to open valves to drain water/oil out of the air tanks each morning.
1) Disconect station air supply and / or shore line
2) Start Truck and build air pressure.
3) Shut the motor off but leave the ingnition in the on position
4) Watch the air pressure for 2 minutes the pressure should not drop.
5) Depress the brake pedal all the way, the air pressure should not drop in 1 minute.
6) Release parking(spring) brake and start pumping the brake pedal, the parking brake should set just under 55 - 60 psi.
7) Continue pumping the brakes until the air system is empty
8 Start truck up and let the air pressure build at idle. Depending on size of the air tanks this should take from 2 to 5 minutes.
Pierce
Ken,
I don't know if matters to you at this point, but my coach has a factory installed GAST 120VAC,3/4 hp unit without a tank and it feeds into main system. My coach is pre-HWH and has the all mechanical air level system (it's quite clever-I'll have to do a post on it sometime) that comes on to keep the coach level. Its on a standard pressure switch (on at 75 psi, off at about 100 psi) and mounted under the stairs. They even installed a tire fill hose with a holder to wrap the hose around for storage. The coach is in storage now so the air schematics isn't handy to see how they feed into the system. I don't know the HWH system very well but I believe they have a small compressor. I don't know why you could tap into that line? There should be a protection valve unit between the HWH compressor and the brake system.
One thing I added is a cooling loop on the output with an air dryer. I found it strange that the factory didn't install one - but it worked fine for the first 15 years of the coaches life before I added it.
@John Thanks for the information. Having an electrical air compressor to supplement the engine air compressor seem like a logical accessory to me. You have peaked my curiosity with your mechanical air level system. When you are up for it please post a description of it and of course pictures! I find it strange the factory didn't install an air dryer with your GAST. You were wise to do it.
see ya
ken