Abstract: A combustion gas powered tool includes a member defining a part of cylindrical combustion chamber having an axis. A piston is movable in a direction along the axis of the combustion chamber. The piston defines the combustion chamber in conjunction with the member. A mixture of air and fuel is generated in the combustion chamber. The air-fuel mixture in the combustion chamber is burned to drive the piston. An orifice grille extends in the combustion chamber, and is parallel to the axis of the combustion chamber.

Abstract: A combustion gas powered fastener driving tool includes inlet and outlet openings through which the combustion gases are discharged from a combustion chamber. These openings are located above the uppermost driving position (top dead center) of a slidable piston, so that an air and fuel mixture is fully trapped in the combustion chamber until after it is combusted. Since an outflow of the unburnt air and fuel mixture is completely prevented, the rate of fuel consumption of the fastener driving tool is high and there is no danger of accidental explosion of unburned fuel even when the fastener driving tool is used in a badly ventilated working place or site. An electric fan for forcing fresh air into the combustion chamber is disposed outside the cylinder and isolated from high temperatures. The fan is durable in structure and reliable in operation.

Abstract: An automatic nailing apparatus includes a housing having a piston driving system for driving a piston, a percussion rod having a concave at only the tip thereof, a nosepiece having a round channel being provided with a pair of nail head guide rails, and a nail magazine for supplying interconnected nails. The forefront nail of the interconnected nails can be nailed in a direction normal to a workpiece because a point of application on nailing exists on the center axis of the forefront nail.