Abstract: A pneumatic actuator (240), comprising: a pressure reducer (270) for delivering gas under a reduced pressure to a control valve; the control valve (280) selectively supplying gas to a pneumatic cylinder (290) or discharging gas from the cylinder (290) to the environment; a replaceable gas capsule (260) for supplying the gas under increased pressure; where the actuator has a first mode of operation for moving the piston (293) to the extended position, and has a second mode of operation for retracting the piston (293). A method for assembling a pneumatic actuator. A portable tool, a clamping device, a screw clamp comprising such a pneumatic actuator. A method for assembling the screw clamp. A method for repairing the screw clamp.

Abstract: A pneumatic actuator (240), comprising: a pressure reducer (270) for delivering gas under a reduced pressure to a control valve; the control valve (280) selectively supplying gas to a pneumatic cylinder (290) or discharging gas from the cylinder (290) to the environment; a replaceable gas capsule (260) for supplying the gas under increased pressure; where the actuator has a first mode of operation for moving the piston (293) to the extended position, and has a second mode of operation for retracting the piston (293). A method for assembling a pneumatic actuator. A portable tool, a clamping device, a screw clamp comprising such a pneumatic actuator. A method for assembling the screw clamp. A method for repairing the screw clamp.