Patent ID: 7942710

Claim:
A hydraulic drive system for an amphibious all-terrain vehicle comprising: a first hydrostatic pump that is selectively fluidly connected to a first hydraulic water propulsion device and a first plurality of hydraulic wheel motors via a first hydraulic manifold assembly and a second hydrostatic pump that is selectively fluidly connected to a second hydraulic water propulsion device and a second plurality of hydraulic wheel motors via a second hydraulic manifold assembly, wherein each of the first and second manifold assemblies further comprises a manifold, said manifold defining four ports; a three-way valve fluidly connected between the hydrostatic pump, the first port defined in said manifold, and the hydraulic water propulsion device, whereby the three-way valve selectively allows fluid flow between the hydrostatic pump and either the manifold or the hydraulic water propulsion device; a water propulsion device isolation valve fluidly connected between the hydraulic water propulsion device and the manifold, said water propulsion device isolation valve being mechanically connected to said three-way valve whereby when said three-way valve selectively allows fluid flow between the hydrostatic pump and the manifold said water propulsion device isolation valve is closed to fluid flow and when said three-way valve selectively allows fluid flow between the hydrostatic pump and the hydraulic water propulsion device said water propulsion device isolation valve is open to fluid flow, thereby allowing fluid flow between the manifold and the hydraulic water propulsion device; a wheel motor valve fluidly connected between the second port defined in the manifold and the plurality of wheel motors; and a wheel motor bypass valve fluidly connected between the third port defined in the manifold and the hydrostatic pump and mechanically connected to the wheel motor valve whereby when said wheel motor valve is open to fluid flow between the manifold and the plurality of wheel motors said wheel motor bypass valve is closed to fluid flow between the manifold and the hydrostatic pump and when said wheel motor valve is closed to fluid flow between the manifold and the plurality of wheel motors said wheel motor bypass valve is open to fluid flow between the manifold and the hydrostatic pump.