Being a relative newbie I sometimes have a problem 'thinking outside of the box'. I've noticed some references to manual air systems, assuming that means removing or bypassing the leveling valves, and that's something that Fred Hobe and I talked about a couple of weeks ago when I stopped there.
As far as I'm concerned it's a foregone conclusion that before changing anything in the air suspension system it would be necessary to test each air beam/bag combination to make sure there are no leaks. That being done then install the manual system. The advantage being that the bus suspension system (like a tire) would hold air and not settle. Mmmm, sounds good to me.
But, as always, that brings up other questions. How then does one determine what pressures to run front/rear or side/side? Too then, without the levelers there's no recovery in cornering as with the valves
(albeit slow in recovering...it does recover).
Any thoughts? Remember..I have a MC5 so probably don't encounter some of the problems you big fellas do with the 40'ers and the tag axles.
NCbob
Only reason I can see for a manual system would be to make the coach level on unlevel ground.
I think as far as ssettling, which is cause by leaks you still have that possible failure in a manual system.
You also will likely lose some of your ride comfort......the system as designed is constantly adjusting things via the leveling valves.
Just my opionion
When parked, movement of the coach causes the leveling valves to adjust the air volume in the bags. With no air in the system, air flows out of the bags, causing the bus to settle.
I made a system for our MC-8 that still uses the OEM leveling valves when driving, but takes them out of the system when parked. My set-up closes the air line between the air bags and the leveling valves using solenoids. 2 additioinal solenoids on each corner add or remove air form the air bags to level the coach (within the limit of air bag travel). We also installed a dump on the tag axle. Jack
jacks system makes sense.
you could also just get a small electric compressor and plug it into shop air inlet........and add a redundant compressor. I lost a compressor once and bought a cheap electric compressor.......which more than provided the needed air to get home where I could make the repair myself.
I highly recommend you keep the original leveling valves for driving down the road. Otherwise, you'll have to be constantly measuring the ride height (or the height of the bus from the road) for proper ride height in relation to loads taken in and released (like when you dump your tanks, fill with fuel, use fuel, fill propane, etc). I also made my own leveling system that uses Skinner 12v continuous duty solenoids. One is in the line between the current leveling valve and air bag that cuts off the air supply to the air bag when activated, then tee'd inbetween the solenoid and the air bag two more solenoids for either adding or exhausting air from the bags. Works well, and can level the bus in less than a minute at the campsite, or just dump them altogether to get it low enough where I don't need an additional step to get into the bus. Plus if you do blow a leveling valve, can go on down the road in manual mode. Good Luck, TomC
Jack, are those solenoids you used constantly on when driving or do they only use power when they are being switched?
I used a Skinner 3-way valve to switch between leveling valve and manual control. They default to manual so that no power is used when parked. They automatically switch to the leveling valves when the master switch is turned on. On 24 volts they draw less than one-half amp when energized while driving.
Jack, are those solenoids you used constantly on when driving or do they only use power when they are being switched?
They are using power when in the open position, similar to the engine stop solenoid (except these have a larger orifice).
The ones used to keep the air flowing from the leveling valves when the master switch is on, are using power all the time the master is on (like the engine stop valve). When parked, the only time they use any power is during the leveling operation. We have stayed for 2 weeks with no "air drain down". Jack
There are always two sides of the coin. I understand Jack's system, but my theory is to have everything off when driving down the road so that nothing can fail causing inconvenience (although those solenoids are very reliable). So mine are activated when you want to use them in manual mode. The down side is that as long as you are camping they are activated, but they do use very little current. Same idea, just different actuation theory. Good Luck, TomC
Do they make solenoids that only use power when switching, but not when in either position? the electrical analogy would be like a latching relay?
Latching Solenoid Valves: Most of the standard Skinner valves are available with a "Magnelatch" operator. This operator uses a 20 msec pulse to operate the solenoid and then it is held by a permanent magnet.
Doesn't a member of this board (I can't remember his name) offer a pre-made system for air levelling? I seem to remember reading a post by another member who used his system. If one were really concerned about reliability, a couple of manual ball valves in the front and rear bays could be used to level the system when parked and to switch it back to automatic when travelling. I believe J.R. has a system like this.
David
Pete Pappas (Daytona RTS) sells a system that is very similar to the one I made. Jack
I do not know about 40 footers, RTS ect. But on our little 35 ft MCIs there is no reason to leave the original system intact. Ride quality and handeling are not affected by the change.
Load the bus up the way you are going to travel in it. Then get out the service manual go to the suspension section, look for the pictures of the front and rear suspension. You will see dimensions at the axle bumpers. Add or reduce air pressure to obtain these dimensions, note what they are on each individual gauge. Use that # each time to level your bus for traveling. Unless you have a 400 lb freshwater tank or a 1000 gal fuel tank, or something else to cause sever weight changes, you will encounter no problems. When you purchase valves for the system buy one extra to carry with you, this will ensure that you never have a problem.
I did leave the original system in the bus. It is still there just unhooked.
When doing the change do not use 2 seperate valves for the front of the bus, this will cause unpleasent cornering! .
. I've used this system for about 5 years and 20K miles with no problems. I have left this bus sitting for 5 months and returned to find it almost the same as I left it!
All of this is of course only my opinion and experience. It is no way intended to sound like it is the right way to do it. Or the only way to do it. I explored the options and did what made the most sense to me. HTH
Kenworth uses an inexpensive valve that is frame mounted. It uses an arm that then connects to the differential to control the amount of air needed to obtain the set height.(Length of arm). If you are loaded or mt the ride height never changes.
The tags aren't a problem as they don't "level" or have leveling valves. They stay at about 35lbs no matter.
I have more of a "Fred Hobe" leveling system. I use the rear leveling valves when driving, but isolate them with ball valves when parked. It allows a good bit of lateral leveling. They can be overinflated or dumped.
The front airbags are totally mechanical. Controlled by an IR adjustable regulator. The bags can be dumped, overinflated for height, or just set and forget. Once set to 60 lbs, they never require any adjustment. The ride height (front only) isn't affected by fuel or anything else. When I first installed this system, ride height dimensions were checked before and after fueling, and no difference was noted. Even my 800 lb spare tire has no effect on the ride height. ;)
The leveling system has been on the bus since '02. The only problem, was leaking airbags. Any leak in the leveling system will render it useless. Had to replace both front airbags and all four drive axle bags. Since they are isolated when parked, the tags and bus system don't have any effect on the leveling airbags. Nor does the leveling function negatively affect the tags. They bleed out any excess over 35 lbs no matter.
The bus drives a lot better at normal ride height.
I've heard that the small adjustable regulators wouldn't last in this environment. So far, no problem.
About the only mod I'd make to the system would be to add a fixed diaghram pressure regulator in the supply line to the adjustable regulator in order to prevent major overinflation of the airbags. I've not done this, but overinflation is possible...up to the limits of the gov. The airbags ain't gonna like 120 lbs of pressure. About 80 lbs is a good limit for new airbags.
I created this system because the bus wouldn't go into the barn with the rooftop ACs. Necessity is the mother of all inventions! The bus is easy to level, or totally dump. Comes down in a hurry too. Doesn't go up quite as fast. But it'll rise as fast as air builds. Both ends will come up to operational height in 15 seconds. When the bus is aired up.
With my DDEC, I can hit the fast idle as soon as the engine fires. Not a lot of waiting. The bus airs up fast with the suspension already inflated.
FWiW, JR
Quote from: DavidInWilmNC on April 23, 2007, 12:23:14 PM
If one were really concerned about reliability, a couple of manual ball valves in the front and rear bays could be used to level the system when parked and to switch it back to automatic when travelling. I believe J.R. has a system like this.
David
Ahhhh yess. I have a poor mans system that has been totally flawless....once the new airbags were installed.
It's described in boring detail below.
David, where's T'vill gonna be held this year? Your place? Gimmie the date.
i'll be there!
I'm bummed about Dallas' T'ville. Man that was some good food! And GREAT entertainment! ;D
I can do it here too....just not a campground. But big flat 12 acres. Got water, some power for the lucky ones....Me feeling lucky, let me know.
I'm open for suggestions. Have to get Dallas and Cat up here to run it. But we have a good bit of covered area in case of inclement weather.
We will be gone a good bit but if anyone's interested, I'll post dates.
Gene L would have to cook. That it. Gotta have him on Barby.
Well guys, it's past my bedtime and it's probably looking like such.
Best, JR
I just install Pete's campground air level kit on my Prevost and it works great. Highly recommend it.
Ron
Four air seat valves,four gauges, a hand full of air brake fittings and dot airline...last 3 buses have been air suspension ,same system put on all...If you actually use your bus this system lets you be level nearly anywhere you end up...In over 20 years and a few hundred thousand miles no problems..gg04
I don't really see much need (at this point, anyway) in much more complexity than your system. After all, one's got to get out to plug the bus in, hook up water, etc, so what's with opening a bay door to adjust a couple of valves? I need to take a closer look at your system and do something similar.
I'm hoping we can have another 'regional' get-together like at Timmonsville with Dallas and Cat. In fact, we
need to have one. That first one was my first experience up close and inside of a converted bus. Here I am, working on converting mine and I'd never been in one! As much as I benefit from all the info available here on these forums, there's no substitute for for actually being there. Plus, the food and entertainment were outstanding. I'm gonna miss Timmonsville next month, that's for sure.
David
Quote from: NJT5047 on April 23, 2007, 08:42:01 PM
Quote from: DavidInWilmNC on April 23, 2007, 12:23:14 PM
If one were really concerned about reliability, a couple of manual ball valves in the front and rear bays could be used to level the system when parked and to switch it back to automatic when travelling. I believe J.R. has a system like this.
David
Ahhhh yess. I have a poor mans system that has been totally flawless....once the new airbags were installed.
It's described in boring detail below.
David, where's T'vill gonna be held this year? Your place? Gimmie the date.
i'll be there!
I'm bummed about Dallas' T'ville. Man that was some good food! And GREAT entertainment! ;D
I can do it here too....just not a campground. But big flat 12 acres. Got water, some power for the lucky ones....Me feeling lucky, let me know.
I'm open for suggestions. Have to get Dallas and Cat up here to run it. But we have a good bit of covered area in case of inclement weather.
We will be gone a good bit but if anyone's interested, I'll post dates.
Gene L would have to cook. That it. Gotta have him on Barby.
Well guys, it's past my bedtime and it's probably looking like such.
Best, JR
Hi
Here's some pics of the G4 Leveling Sytem - I make
I have the four point manual system on an 4106 and I get 10 inches of vertical at each corner, onch had to use it to get off high center, just air up and drove off.>>>Dan
I also use our to get a better drain of our holding tank. Connect drain hose, then raise passenger side of bus. Jack
Also use system for working on bus!