A new and different seat suspension suitable and advantageous for off-the-road and highway vehicles is presented. Contributing to a comfortable ride for the operator are several proved features, to which have been added three new and unique features.The seat suspension is an air-oil cushioning system to which has been added a servo-linkage to operate a two port hydraulic valve; the servo-linkage being tied to the vertical seat motion.The new, unique features are: 1.Unlimited range of adjustment of seat vertical position to suit the individual operator, assuring him of easy access to the brake pedal, good vision, and comfort, regardles of his particular body dimensions. 2.At any vertical seat position the operator chooses, automatic adjustment for the weight of the operator. 3.Clearance between the front edge of the cushion and the rim of the steering wheel, once set to the operator's liking, is maintained, including the time while the operator is dismounting and remounting. On other air cushion seat suspensions with motion restrained to vertical up and down as this one is, no such maintenance of clearance occurs, and dismounting as well as remounting is difficult as a result.