A shock absorbing bias means in the form of an air spring is positioned in sandwiched relation between the top and bottom plates. Although depicted in the center thereof, such central positioning is not critical but it is preferred. The bot- tom plate of the platform supports the air spring housing and the top of the air spring housing is secured to the underside of the top plate of the platform. The air spring therefore provides a bias means that resists movement of the top and bottom platforms relative to one another. More importantly, the air spring recovers quickly after it has been fully compressed.

Accordingly, it returns to its position of repose quickly after 4O

absorbing an externally-imparted force.

The amount of resistance offered by the air spring is adjust- able. More particularly, air from a remote source of air under pressure may be added to the air spring through an air io1et/ outlet port to increase its resistance and air may be released 43 from said air spring at said inlet/outlet port to decrease its resistance. Significantly, the air inlet/outlet port is positioned

at the front of the novel platform so that it is easily accessible and no part of the novel assembly blocks access to said port. If the platform is positioned in a recess that blocks frontal access, then the air inlet/outlet port is routed vertically to provide access from the top.

In a preferred embodiment, a damper is disposed between the top plate and the bottom plate at a preselected location offset from the centrally-mounted air spring. However, in additional embodiments, a second damper may be positioned on an opposite side of the platform but it is believed that a single damper can provide the required damping effect.

The damper may be mounted in six basic ways.

In a first way, a first end of the damper is pivotally mounted 60 to a bracket assembly mounted on the bottom plate at the rear or trailing end of the platform and a second end of the damper is mounted to the vertex of a “V”-shaped linkage where the vertex is equidistant between the top and bottom plates at the forward or leading end of the platform. 65 In a second way, the first end of the damper is pivotally mounted to a bracket assembly mounted on the top plate at the damper is mounted to the vertex of the “V”-shaped linkage where the vertex is equidistant between the top and bottom plates at the forward or leading end of the platform.

In a third way, the first end of the damper is mounted to the vertex of the “V”-shaped linkage where the vertex is equidis- tant between the top and bottom plates at the rear or trailing end of the platform and the second end of the damper is pivotally mounted to a bracket assembly mounted on the bottom plate at the forward or leading end of the platform.

Ina fourth way, the first end of the damper is mounted to the vertex of the “V”-shaped linkage where the vertex is equidis- tant between the top and bottom plates at the rear or trailing end of the platform and the second end of the damper is pivotally mounted to a bracket assembly mounted on the top plate at the forward or leading end of the platform.

In a fifth way, the first end of the damper is engaged to the vertex of the “V”-shaped linkage at the trailing end of the platform and the second end of the damper is engaged to the vertex of the “V”-shaped linkage at the leading end of the platform.

In a sixth way, the second end of the damper is engaged to the vertex of the “V”-shaped linkage at the trailing end of the platform and the first end of the damper is engaged to the vertex of the “V”-shaped linkage at the leading end of the platform.

The air spring resists external forces abruptly applied to the top and bottom plates that cause the distance between the top and bottom plates to change from their equilibrium distance and performs the further function of returning the top and bottom plates to their respective initial positions of repose.