A system, apparatus and method for detecting and controlling the height of a frame of a self-propelled agricultural product applicator above a ground surface utilize a trailing link suspension system including an angular position sensor and extensible air strut, for connecting ground engaging wheels of the applicator to the frame of the applicator. Height of the applicator above the ground surface is determined by measuring relative angular rotation of upper and lower suspension arms of the suspension system about a suspension pivot axis, using the angular position sensor. Height is controlled by regulating a flow of pressurized air to the air strut, to thereby control extension of the air strut in a manner that controls a frame to axle, ride-height, distance of the suspension system.
