A little technical question on ride height sensors

[FIRE UP]

Gents,
Just wondering. If a vehicle, as in our '04 Itasca Horizon 36GD with the 330 CAT, has ride height sensors, both on front and rear, do they only compensate for loads, "fore and aft" only? That is, if you weigh all four corners and, the two rears are say, a couple of hundred pounds apart and, the same results are in the front axle, but, there's only one ride height sensor for the front axle and one for the rear, then as the sensor for each axle is trying to compensate for what the default height is supposed to be, is it sending signals to the computer which, in tern controls the air bags, how is it telling each air bag on each axle to lift or not?

Anyone getting what I'm asking here? I could see if there were two ride height sensors on each axle. That way, each could tell the computer to raise or lower the pressure for the wheel their responsible for. But, there's only one on each axle. Just kind of wondering here.
Scott

[Martind4]

I think you'll only find 3 ride height controls, 2 on one axle and 1 on the other. The configuration is determined by the coach mfg, not Freightliner.

Our coach has 2 ride height controls on the front axle and one on the rear axle. That gives both fore/aft and side to side. I also don't think a "computer" is involved, the single sensor controls the rear axle ride height. Each of the front ride height sensors controls each of the front air bags.

Ride height and leveling is "automatic" as long as there is sufficient air pressure in the system.

If you happen to have the HWH Active Air system, the whole thing gets a lot more complicated because it will actually "lean" the rig into corners,

[336muffin]

Ride height is controlled by a valve that is linked to the axle and when more load is placed inside the vehicle. This opens the valve and inflates the bag (air spring) until the frame is back at ride height. When the load is removed, air is bled off. Some manufactures use 1 valve per axle and this always equals from side to side with no binding or fighting with the opposing side. Some use two valves per axle and when the coach rounds a curve the low side calls for more air which force levels the vehicle. Air ride suspensions are a fantastic design with few moving parts, usually what wears out is the valve which is relatively easy to replace and economical. I will also add that any under the coach is dangerous, ESPECIALLY when working on this system. I have owned semis and trailers with air springs and have never had to replace a bag. And very few Neway air valves. Hope I answered your question. I have never had a air ride suspension that was tied to a computer. If one valve per axle is used, both bags are plumbed together so they will always be equal no matter the weight. Older suspensions would gush air from one bag to another when cornering at speed or entering a driveway entrance, but the newer have check valves now that compensate for this.

[FIRE UP]

Wow guys,
Those two answers are way more than I expected. This is cool. I'm learning things all the time. I only surmised that a "computer" was involved in the ride height process because in today's autos, trucks, motor homes, etc. computers handle a lot of decisions on just about every phase of operations. I'm amazed at air bags anyways. Those things seem just about bullet proof. The live in the utmost lousiest conditions, handle the entire load of the vehicle minus the un-sprung weight and still hold up for eons of time. Now, to learn that they "learn" for cornering, rounding on-ramps for freeways etc. that's neat. Thanks again for your help on this subject. Always glad to learn more about my own and others rigs.
Scott

[Mr_D]

I have yet to see a MH with only two ride height valves. There are either two in front and one in the rear or one in front and two in the rear.
No computer involved in most systems, the HWH and some others may be an exception.

[MaverickBBD]

Also as the air goes out of the "bag" it goes into a 'ping' tank. The back and forth movement of air is what contributes to the "Wal Mart Wobble". Some aftermarket systems up size these air lines to lessen it.