Low-frequency-rate spring suspension system for a wheeled vehicle

Claim 1

A low-frequency-rate spring syspension system for a wheeled vehicle having a frame with a first spring bracket, comprising: a second spring bracket secured to said frame and having guide means depending therefrom providing a pair of laterally spaced walls an upper and lower limit means, an axle, a metal leaf spring having one end shackled directly to said first bracket, a central portion secured to said axle, and a second end extending through said guide means in between said laterally spaced walls and between said upper and lower limits, said second spring end being free from attachment to said guide means and to said second bracket so that no vertical load is transmitted therebetween while lateral alignment is maintained, said guide means comprising a pair of side walls each having a vertical elongated slot, a lower sleeve between them, said second spring end lying thereabove, and a roller having ends mounted in said vertical slots for free vertical movement therealong, said roller being located above said spring's second end, an air spring secured to and between said frame and said leaf spring in between said second end and said central portion, said air spring thereby being offset from said axle, and height-control means for controlling the height of said air spring so that said second end is ordinarily prevented from making contact with said second bracket, whereby said leaf spring positions the air spring relative to said axle and provides roll resistance, while said air spring and the leaf spring are in parallel, the air spring carrying most of the load, the percentage split of load between the two springs remaining constant.