Combination hydraulic-penumatic suspension system for vehicle occupants

Claim 1

A vehicle occupant support suspension system comprising in combination: a. a vehicle frame; b. an occupant seat support frame vertically movable with respect to said vehicle frame; c. first hydraulic cylinder and piston means defining a first chamber interposed between said vehicle frame and said occupant support frame; d. second hydraulic cylinder and piston means including a fixed member and a movable member and defining a second chamber, said movable member being hollow and having first and second ends, said first end including an axial opening into which said fixed member extends; e. a hydraulic connection line interconnecting said first and second chambers; f. air cushion means including a fixed portion and a movable portion defining a third chamber, one of said portions including a piston, the said movable portion of said air cushion and the said second end of said movable member of said second hydraulic cylinder and piston means being affixed to each other and operatively associated to move together in response to pressure changes in either of said second or third chambers, the fixed portion of said air cushion means and the fixed member of said second hydraulic cylinder and piston means being mounted on one of said frames, the effective area of the piston portion of said air cushion being greater than the area of the piston portion of said second hydraulic cylinder and piston means; and, g. means communicating with at least one of said chambers for permitting fluid to be added to or removed therefrom.