Auto Level Control: Operation
During vehicle operation hydraulic oil from reservoir flows freely through system. When weight is added, fluid will flow to struts. In this position the leveling valve is actuated by a lever attached to the torsion bar. Leveling valve is now switched from "neutral" or "return" flow to "filling" position and hydraulic fluid flows through check valve, into pressure unit and spring struts.
Added fluid causes spring struts to extend and raise rear of vehicle until leveling valve is moved back to the neutral position. When added weight is removed, rear of vehicle raises which moves leveling lever to return flow position. This allows fluid in the spring struts to drain back into the reservoir until leveling lever is in neutral position.
NOTE:
Raising of vehicle rear end should never be attempted by adjusting connecting rod of leveling valve. This would cause vehicle level to be continuously regulated too high under load. The result would be poor ride characteristics and knocking noises during deflection. Also under heavy load and acceleration, there would be maximum pressure in suspension elements (limited by leveling valve) and the opening noise of the pressure relief valve would cause a whistling and knocking noise.