Patent ID: 8261869

Claim:
An agricultural vehicle having a vehicle hydraulic system and a cab for the vehicle operator, the vehicle comprising: a self levelling suspension system having a plurality of suspension units each having a spring, a damper and an accumulator, wherein the accumulator comprises a hydraulic working chamber that is separated by a movable wall from a gas filled chamber serving as a spring, and is connected to at least one working chamber of the damper in a closed hydraulic circuit; and a hydraulic actuator configured to be powered by the vehicle hydraulic system and configured for powering hydraulic fluid to flow in the closed hydraulic circuit between the hydraulic working chamber of the accumulator and the at least one working chamber of the damper, wherein the hydraulic actuator is formed as a separate unit having two hydraulic working chambers separated by a movable wall, one of the working chambers connected by an associated changeover valve to a supply and a return line of the vehicle hydraulic system and the other working chamber connected to the hydraulic working chamber of the accumulator, so as to vary the height of the cab without any fluid from the vehicle hydraulic system entering or leaving the closed hydraulic circuit of the damper and the accumulator.