Patent ID: 7611126

Claim:
A pneumatic actuator device for connection to a source of compressed gas for acting in a linear direction, the device comprising; an elongate, generally tubular, hollow member extending in the linear direction, the hollow member including a slot formed therein extending in the linear direction; a carriage supported for sliding movement in the linear direction along the elongate hollow member between opposed ends of the member; an expandable bellows member housed within a hollow interior of the elongate hollow member and extending between a fixed end and a movable end; the fixed end of the expandable bellows member being fixedly mounted at one end of the elongate hollow member in fixed relation thereto; a link member extending through the slot and fixedly coupling the movable end of the bellows member to the carriage so as to be arranged for movement of the movable end of the bellows member together with the link member and the carriage along the elongate hollow member; a stop member mounted on the hollow member so as to prevent the movable end of the bellows member from extending beyond an end of the hollow member in a fully extended position of the bellows member; and the bellows member being formed of flexible material so as to be arranged to be expandable in the linear direction; and a lift control comprising a supply valve selectively coupling the bellows member to the source of compressed gas to expand the bellows for displacing the carriage along the upright in a first direction and a vent valve selectively coupling the bellows member to a vent to contract the bellows for displacing the carriage along the upright in a second direction opposite to the first direction; the supply valve and the vent valve being arranged to communicate with the bellows member adjacent the fixed end; and the bellows member haying an outer diameter which is near in dimension to an interior dimension of the hollow member such that: the hollow member provides support to the bellows member formed of flexible material during expansion and contraction of the bellows member; and the hollow member concentrates expansion and contraction of the bellows member formed of flexible material in the linear direction.