Patent ID: 7314394

Claim:
An amphibious vehicle having retractable wheels and a retractable suspension, comprising: (i) a hydraulic actuator acting as at least part of a suspension for each wheel, (ii) each actuator having a first chamber at a wheel raised first side, and a second chamber at a wheel lowered second side of the actuator, (iii) a hydraulic fluid pump arranged to be coupled selectively to either the first or second chamber of each actuator, (iv) an accumulator for each actuator and connectable thereto and to the pump, (v) each said chamber having at least one switchable valve in a conduit between that said chamber and the pump, (vi) a controller arranged to control each said valve, (vii) at least one fluid pressure sensor arranged to detect actuator pressure and to indicate to the controller when a predetermined threshold has been reached, (viii) the controller being arranged by controlling the valves to extend the wheels from a retracted position in a marine mode to an extended position in land mode, to pressurize each accumulator, and to isolate the actuators and accumulators from the pump, (ix) the controller is arranged to pressurize at least one accumulator when a signal is received to indicate that a predetermined suspension pressure has been reached.