When I bought my coach, I was concerned about the clearance of the rear in making the transition from the street to my driveway. I rigged up the following in 2006. Subsequently, I posted it to the files section of the Monaco Monaco yahoo site. That was in 2010. Attached is a copy of that file. A few years later I saw a reference to the Source Engineering version. I don’t know if they copied it from my file of came to the same version on their own. In any case, my version shows how it worke to raise the rear for increased clearance.
Dick L. ‘04 HR Imperial
The suspension on my '04 HR IMPERIAL consists of 8 airbags, 4 for the front axle and 4 for the rear. The height is adjusted automatically with ride height valves that senses the distance between the axle and the frame of the coach. If the distance is too much, the valve lets air out of the air bags; if it is too little, it adds air from the coach air supply. The system is completely automatic and compensates for load in the coach. The front axle has a single ride height valve, and the rear has two, one for each side. The rear end of this coach drags as I start up the drive and it needed to be raised by a couple of inches to clear.
I found some 12 volt solenoid valves at WW Grainger that had 3 ports on them. The common port is switched from one port 1 to port 2 when 12 volts is applied. I used two of these valves to connect the air bags to the coach high pressure when a push button on the dash is depressed. When the button is released, the air bags are connected to the ride height valve and the system is returned to the normal height. It takes about 30 seconds for the coach rear end to rise up about 3 inches, which is more than enough to clear my driveway.
. By the way, the total parts cost (2 valves, several 1/4 inch tees, wire, fuse and air line was under $100.
In the schematic diagram, you can see how simple the change is. The diagram shows the original and modified plumbing. It only shows the system for one half of the rear axle suspension. Potentially, the biggest hurdle would be getting a wire from the front of the coach to the solenoids, which were mounted on the frame above the rear axle. Fortunately, the coach had a wire which was installed by the previous owner for an electrical brake system. I have the M&G system which uses only connection to the air brake lines.
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The valves were Grainger 6JJ52 and were $27.90 at my local store. I used normal compression 1/4 inch Tees with inserts in the tubing. By the way, the tubing is nylon, not polyethylene. I bought the tubing at a local truck repair facility. You can use the quick insertion tube fittings, but by the time I found out where to get them, I had bought the Tees at my local Home Depot. Again, my coach requied two sets of everything, one for each side. I fabricated a small bracket to hold the solenoid valves and screwed it to a framing member on the underside of the coach, up where it would stay relatively clean. Also, all loose tubing was strapped down with tie-wraps.
The same method could be applied to the front suspension, which has only one leveling valve. All the front air bags are connected in common, which reduces the roll resistance. This helps to keep all the wheels on the ground on uneven surfaces.
Showing the ride height adjustment valve for driver’s side. When the axle is too high, the valve admits air to the bags, increasing the distance from the frame to axle.
close-up of ride height valve. One hose is high pressure air, the other is the connection to the air bag. Seen at the lower right is the vent to atmosphere. The arm connecting to the sensing rod is in the background.
mounting of solenoid valves on frame member. Both valves are bolted together. Lines have protection loom and are secured with tie-wraps.
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close-up of solenoid valves