Remove leveling valves - install manual system

Jim Blackwood · April 17, 2019, 08:41:23 AM

I'm grateful for this chance to learn ahead of time. Spme of these are pretty sophisticated. They lock in position if the supply tank is under 65 psi, so this is how you bypass the automatic system for leveling in camp with the manual system? I was wondering how that would work. Both systems stay fully operational but you dump the air from the supply tank and use another source to level manually is what i got from that.

It also sounds like there are two types of systems, one with a link to the axles like on a semi that just maintains body to axle height, and one that has some sort of level sensor? (like a turn and bank indicator)

Dave, are you willing to share where you got your dual gages and those slick fill/drain valves?

Jim

gg04 · April 17, 2019, 08:53:59 AM

All of the commercialy avalible systems Ive ever seen have been 4 point. 4valves 4gauges.. We run 40 right & left front, 48 right rear & 45 left rear..our normal road settings, we weigh 24580 lb fully loaded...

Dave5Cs · April 17, 2019, 09:32:47 AM

Jim these are where we got them. You can get them assembled for 30.00 extra or they send all the parts and they just snap together no big. Also have 3 ways and two ways etc.

https://www.avsontheweb.com/4-x-pneumatic-switches-dual-gauges-panel-with-fittings-airline/

Another one who makes similar stuff is Airbagit.com

sledhead · April 17, 2019, 09:36:04 AM

I have a 3 point level system in my featherlite now but later years
( newer) they ( hwh ) used a 4 point system as I think it makes it easier to level the coach .

on the M C I it had a 4 point system and in the 10 years I had it never a problem

dave

richard5933 · April 17, 2019, 09:58:30 AM

Quote from: sledhead on April 17, 2019, 09:36:04 AM
...on the M C I it had a 4 point system and in the 10 years I had it never a problem

dave

~~Big difference between a GM and MCI. The MCI buses use body-on-frame, as does nearly every Class A diesel pusher out there. The GM buses are unibody with no actual frame.~~ (Corrected)

The 3 height control valves in a GM still control air bags at four corners, not a tripod of air bags. The front one will adjust the pressure in the front two corners, raising or lowering the front of the bus. The rear valves each control one side at the rear. If one rear corner goes up or down, the corresponding corner at the front follows since the air can flow between the front two corners.

This isn't the same as a tripod leveling system used in some trailers that has one jack at one end and two at the other end - the GM bus is still supported at all four corners. However, with the factory setup only one axle can be controlled for side-to-side adjustment - the other just follows along.

Ed Hackenbruch · April 17, 2019, 10:47:40 AM

Our MCI 5A did not have a frame, don't know if any of the MCIs ever had a frame.....don't think so.

Dave5Cs · April 17, 2019, 11:09:28 AM

Nope our 5C is the same unabody no frame. Originally it had one leveler in the front same as yours that controlled up and down tilt and the rear has 2 one at each side to control side to side which actually is a tripod as in 3 levelers just like yours Richard.
I believe Prevost is the only one with a frame in an actual 35 and 40 ft older bus models but i may be wrong on that.

Now we disconnected from the levelers and connected to the paddle valves in the cab that I installed by the drivers left leg and then directly to the airbag so each side can be adjusted singly or together etc.

richard5933 · April 17, 2019, 12:49:56 PM

Thanks for the correction. I thought all MCI buses had a frame. Live and learn.

chessie4905 · April 17, 2019, 02:45:37 PM

That torquing the body is bull. If that could be the case, all our coaches would be twisted.

Dave5Cs · April 17, 2019, 09:03:53 PM

Agree Chessie. If that was the case there would have been a lot of people waiting on twisty roads for another bus with all the luggage. lol

richard5933 · April 18, 2019, 02:36:47 AM

If understand all this correctly (which is a long-shot at this point) there are a few main ways guys crack this nut:

Run a new set of lines to each corner of the bus with a T fitting between the current leveling valves and the air bags. These lines would be fed from the new controls/gauges next to the driver for use in leveling at a campground. When going down the road the regular leveling valves would still do their thing.

or

Eliminate the current leveling valves from the system, and use new feeds from the front controls/gauge to control the ride height as well as leveling when in a campground. This could be done using the existing 3 feed points (2 rear, one front) or by splitting the front and using 4 feed points.

Either option, I need to supply a new master supply line to the new control panel and then a feed line to each of the (3 or 4) feed point.

Question - How well do the controls being used hold air in the long run? Will they maintain the set height (pressure) for days/weeks/months or do they bleed down?

sledhead · April 18, 2019, 05:00:07 AM

Mine held air for months . That's why I ran 1 line to each corner with out any other connections . The air leveling was way faster then the hwh system I have now , maybe because of only air push pull valves and not all the solenoids that control the hwh system

One thing I added was a one way valve and a small air tank for the leveling system to stop any leaking from the rest of the air system

it was a very simple system with all controls right beside my seat so if I needed to I could adjust it on the fly

dave

buswarrior · April 18, 2019, 06:07:27 AM

One thing I don't think was mentioned is the importance of setting proper ride height for motoring.

Suspension geometry has been designed around that height.

On a level surface, get those underbody axle to bump stop distances set, then choose a more readily available external point to do measuring for routine setting. The wheel well, the bumper, the step bottom, whatever.

Happy coaching!
Buswarrior

Jim Blackwood · April 18, 2019, 06:46:48 AM

Too bad there isn't any easy way to monitor the bump stop distance when driving. A simple turn and bank indicator could help you stay level on crowned highways but it looks like you would have to rely on bag pressure to maintain the ride height. I wonder if that relationship stays constant with temperature changes?

I sort of favor the tripod system, and HWI apparently sets up their hydraulic systems that way too, at least Dave's S&S is. I also used a tripod on my old Coachman when I built that system but I only used one cylinder in the front. It worked quite well but as you would expect it was much more sensitive to side/side leveling than front/back. It seems to me that a 4 way system would be sensitive to wracking, and knowing what that does to an offroad truck I'd hesitate to subject something 45 ft long to any more of that than I had to. No matter how rigid it is, that's going to stress the skin. No guarantees I'm going to be the only one to ever mess with the controls, or that an airbag or line won't leak.

Jim

TomC · April 18, 2019, 09:24:24 AM

I kept my 3 position automatic leveling valves. At each position I added 3 air 12v solenoids-one normally open and two normally closed. Between the air bags and the automatic leveling valve I put inline the normally open solenoid. Between the normally open solenoid and the air bags I T'd in the two normally open solenoids. In operation, when I activate the normally open solenoid, it closes off the air line from the automatic leveling valve. Then with the two normally closed solenoids-one is attached to the air system of the bus to add air and the other is to simply exhaust air. So now it takes about 10 seconds to level my bus. I used RedTop solenoids and the switches are right behind the driver's seat. Good Luck, TomC