Patent ID: 7530577

Claim:
An air suspension system for a load-bearing vehicle including first and second frame members with an axle positioned therebelow, the vehicle also including a source of air under pressure, comprising: a first air spring, having an air inlet/outlet port, positioned between the first frame member and the axle therebelow; a second air spring, having an air inlet/outlet port, positioned between the second frame member and the axle therebelow; a first auxiliary air reservoir having an air inlet/outlet end; a second auxiliary air reservoir having an air inlet/outlet end; a first control valve having first and second ports; said first control valve being movable between open and closed positions; a second control valve having first and second ports; said second control valve being movable between open and closed positions; said second port of said first control valve being in fluid communication with said air inlet/outlet end of said first auxiliary air reservoir; said second port of said second control valve being in fluid communication with said air inlet/outlet end of said second auxiliary air reservoir; a first height control air valve operatively interconnected to one of the frame members and the axle; said height control air valve having air inlet and air outlet ends; said air inlet of said first height control air valve being in fluid communication with the source of air under pressure; a first air dump valve having a first port, a second port and an exhaust port; said first port of said first air dump valve being in fluid communication with said air outlet end of said first height control valve; said second port of said first air dump valve being in fluid communication with said air inlet/outlet port of said first air spring, said inlet/outlet port of said second air spring, and said first ports of said first and second control valves; said first air dump valve being movable between first and second positions; said first air dump valve, when in its said first position, permitting fluid communication between said first height control valve, said first and second auxiliary air reservoirs and said inlet/outlet ends of said first and second air springs; said exhaust port of said first air dump valve being closed when said first air dump valve is in its said first position; said first air dump valve, when in its said second position, permitting the air in said first and second air springs to be exhausted therefrom through said exhaust port of said first air dump valve; said first port of said first air dump valve being closed when said first air dump valve is in its said second position; said first and second control valves being open thereby permitting the flow of air therethrough when said first air dump valve is in its said first position; said first and second control valves being closed thereby preventing the flow of air therethrough when said first air dump valve is in its said second position.