Abstract: This disclosure is directed to a fluid actuated spring assembly for supporting a vehicle load which includes an expandable bellows or chamber having a limiting device disposed internally of the expansion chamber to prohibit or limit the overall height to which the expandable chamber may extend. A control valve is operatively connected to the expandable chamber to control the flow of fluid pressure to and from the expandable chamber, and a valve actuator that is responsive to varying load and/or road conditions is provided to automatically operate the valve to control the flow of fluid pressure to and from the expansion chamber so as to maintain the overall height of the expandable chamber substantially constant, irrespective of varying load and/or road conditions.

Abstract: A tractor-trailer fifth wheel suspension assembly which includes a mounting frame adapted to be suitably connected to a tractor body frame and a movable frame for supporting the fifth wheel mounted for parallel vertical movement relative to the mounting frame, and having opposed complementary stabilizing guide members connected to the respective frames to stabilize and limit the relative movement therebetween. In one form of the invention, the movable frame is supported on the mounting frame by a four-point air suspension system to effect relative parallel vertical movement between the respective frames and which function to automatically laterally and longitudinally stabilize the trailer load relative to the tractor when hauling.