Patent ID: 8342280

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 actuator is integrated with the accumulator into a single unit having two movable walls defining three variable volume working chambers, the variable volume chambers including two hydraulic working chambers separated from one another by a gas filled working chamber, wherein one of the hydraulic working chambers is connected to the working chamber of the damper and the other hydraulic working chamber connected by a single changeover valve to a supply and a return line of the vehicle hydraulic system, 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.