Suspension and leveling system for a vehicle

Claim 1

A suspension system for a vehicle, said vehicle having a vehicle frame with forward and rearward ends and opposite lateral sides, said vehicle also having a vehicle cab and at least one axle extending transversely of said vehicle frame and having opposite axle ends positioned adjacent said opposite sides of said frame; ground engaging wheels being mounted on said axle, said suspension system comprising: an elongated spring means having a first end attached to said vehicle frame and a second end; bag means having an upper end, a lower end and flexible walls enclosing a bag compartment whereby said bag compartment is capable of continuously expanding and contracting in vertical size between expanded and retracted positions in response to the introduction of fluid to and removal of fluid from said bag compartment so as to adjust the vertical distance between said upper and lower ends of said bag means; first securing means attaching said upper end of said bag means to said vehicle frame; second securing means attaching said second end of said spring means and said lower end of said bag means to said axle whereby the vertical distance of said axle below said frame is controlled by the position of said bag compartment between said expanded and retracted positions; a pressurized fluid source; first fluid conduit means connecting said fluid source to said bag means; a height control valve in said first fluid conduit means and having a first position providing fluid communicating from said fluid source to said bag means for introducing pressurized fluid to said bag means and having a second position permitting fluid to exit from said bag means; sensing means connected between said frame and said axle for sensing the relative distance therebetween, said sensing means being connected to said height control valve for moving said height control valve to said first position in response to sensing a relative distance less than a predetermined distance between said axle and said frame and for causing said height control valve to move to said second position in response to sensing a relative distance greater than said predetermined distance; an automatic fluid valve in said first fluid conduit between said fluid pressure source and said bag means; said automatic fluid valve being movable between an open position permitting fluid communication between said fluid source and said bag means and a closed position closing fluid communication between said fluid source and said bag means; first electrical power means connected to said automatic fluid valve for causing said automatic fluid valve to move to its said open and closed positions; manually operable electrical control means located remote from said bag means, said height control valve, and said axle; first electrical connection means connecting said electrical control means to said first electrical power means for controlling movement of said automatic fluid valve between its said open and closed positions; second fluid conduit means connecting said pressurized fluid source to said bag means; second valve means in said second fluid conduit means and being selectively movable to an up condition providing fluid communication from said pressurized fluid source to said bag means and to a down condition permitting fluid to escape from said bag means; second electrical power means connected to said second valve means for causing said second valve means to move between said up and down conditions; second electrical connection means connecting said electrical control means to said second electrical power means for selectively controlling movement of said second valve means between its said up and down conditions.