Abstract:
A level control system for a motor vehicle with an unsprung mass including a wheel, a sprung mass, and a shock absorber connecting the sprung and unsprung masses comprises fluid power apparatus activatable to level the sprung mass with respect to the unsprung mass, a sensor effective to generate a signal indicating the level of the sprung mass relative to the unsprung mass and apparatus responsive to the sensor to compute the difference between the total times, within a predetermined time period, spent by the level above and below a predetermined trim band and apparatus effective to compare the difference of the times with a reference comprising a predetermined percentage of the predetermined time period and activate the fluid power apparatus if the difference exceeds the reference in magnitude, whereby the system can maintain a narrow trim band while the vehicle is not moving while avoiding unnecessary corrections and cycling due to excursions above and below the trim band during vehicle movement over rough surfaces.