Although we often refer to those as leveling valves, the correct term is ride height control valves. Their job is to keep the bus at the right ride height at all times. Consider that a commercial coach is loading and unloading passengers and baggage all the time. Therefore these valves automatically adjust according to the load on the suspension. If there is any manual way to adjust them, it has been added later by an RVer looking to use them for campground leveling.
