Patent ID: 8863641

Claim:
A fluid pressure operated actuator device, comprising: a body defining a first chamber comprising an inlet in fluid communication with a pressurised fluid source; and a moveable element mounted in the first chamber, the moveable element comprising an operative end and partition configured to separate a first region of the first chamber comprising the inlet from a second region of the first chamber opposed to the first region during use of the device, the moveable element being moveable relative to the body between an extended configuration and a retracted configuration, with movement from the retracted configuration to the extended configuration occurring in response to a pressure differential across the partition; wherein the actuator device includes a first passageway for allowing passage of fluid from the pressurised fluid source to a second chamber in the operative end of the moveable element, and a second passageway for allowing passage of fluid from the second chamber to the second region of the first chamber, the operative end being configured to allow fluid in the second chamber to pass between the operative end and a target surface when the moveable element is in the recessed configuration and being configured to abut the target surface when the moveable element is in the extended configuration in order to substantially restrict passage of fluid between the operative end and the target surface.