Tag axle suspension system

#The present invention relates generally to wheeled vehicle suspension systems and, in an embodiment described herein, more particularly provides a tag axle suspension system.

#Tag axle suspension systems are used to increase the load carrying capabilities of a vehicle, such as a dump truck, flat bed truck or a cement truck. When the increased load carrying capability is not needed, the tag axle is raised, so that wheels at each end of the tag axle no longer contact a road surface.

#Often, requirements for tag axles tend to make conventional lift axle suspension systems not generally suitable for use as tag axle suspension systems. For example, since tag axles may be positioned a relatively large distance from the nearest non-lift axle, the tag axles should be raised upward a greater distance to avoid contact with the road surface due to suspension jounce, to avoid contact with debris on the road, and to avoid contact with the road surface due to dips or humps in the road surface.

#FIG. 1 is a perspective view of a tag axle suspension system embodying principles of the present invention;

#FIG. 2 is a side view of the tag axle suspension system;

#FIG. 3 is a top plan view of the tag axle suspension system; and

#Representatively illustrated in FIGS. 1-4 is a tag axle suspension system 10 which embodies principles of the present invention. In the following description of the suspension system 10 and other apparatus and methods described herein, directional terms, such as “above”, “below”, “upper”, “lower”, etc., are used only for convenience in referring to the accompanying drawings. Additionally, it is to be understood that the embodiment of the present invention described herein may be utilized in various orientations, such as inclined, inverted, horizontal, vertical, etc., and in various configurations, without departing from the principles of the present invention.

#In FIGS. 1-3, the suspension system 10 is shown with an axle 12 in a lowered position, and in FIG. 4 the suspension system is shown with the axle raised. In the lowered position, tires on wheels (not shown) attached at opposite ends of the axle 12 are in contact with a road surface. In the raised position of the axle 12, the tires are not in contact with the road surface.

#The suspension system 10 includes a suspension assembly 14 which is unique in the art of tag axle suspension systems. The suspension assembly 14 includes actuators 16 pivotably connected between longitudinal vehicle frame rails 18 and hanger brackets 20. The hanger brackets 20 are rigidly connected at opposite ends of a tubular member 22 which extends laterally across rear ends of the frame rails 18.