Abstract: A fluid pressure operated actuator device, comprising: a body defining a first chamber (2) comprising an inlet in fluid communication with a pressurized fluid source (1); and a moveable element (5) mounted in the first chamber, the moveable element comprising an operative end (4) and partition means (3) 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 means, wherein the actuator device includes a first passageway (7) for allowing passage of fluid from the pressurized fluid source to a second chamber (9) in the operative end of the moveable element, and a second passageway (8) for allowing passage of fluid from the second

Abstract: Apparatus for use as a heat pump includes compression chamber means, inlet means for allowing gas to enter the compression chamber means, compression means for compressing gas contained in the compression chamber means, heat exchanger means for receiving thermal energy from gas compressed by the compression means, expansion chamber means for receiving gas after exposure to the heat exchange means, expansion means for expanding gas received in the expansion chamber means, and exhaust means for venting gas from the expansion chamber means after expansion thereof.