Abstract: By this invention is provided an apparatus and method of improving the ride and handling characteristics of the tractor unit of a tractor trailer rig which is used to haul loads over highways. The apparatus provides an air bellows located above the springs behind the axle of the wheels and in front of the rear shackle of the springs and is designed to apply an adjustable, governed force above the springs in the plane defined by the center line of the tractor frame and the longitudinal axis of the spring.

Abstract: This invention provides an apparatus and method of improving the ride, handling and steering characteristics of the tractor unit of a tractor-trailer rig or a truck which is used to haul loads over highways. The apparatus includes an air bellows spring located directly over the leaf spring of said truck between the steering-wheels axle and the rear shackle of the leaf springs. The air bellows spring is designed and located to apply a manually adjustable force to the leaf springs without creating any torque about the longitudinal axis of the leaf spring.