Abstract: A pneumatic, linear thrust hand tool, such as a nail driver wherein a charge of pressurized gas in a firing chamber acts, when a main valve is opened, to drive a ram downward. The main valve is opened by a higher pressure source gas entering a charging chamber under a piston carried on the valve stem. Then a control valve is released, the pressurized gas under the piston is delivered to the main cylinder to return the ram and, when the main valve is closed, the pressure in the firing chamber is equalized with that in the charging chamber to prepare it for the next "firing".