A two-cylinder two-cycle LP gas operated internal combustion engine provides high speed high energy impacting for driving nails or the like. The two cylinders are geared together by rack and pinion gearing so that the expansion stroke of the smaller first piston provides the compression stroke of the larger impact piston. A first piezoelectric igniter in the nailing end of the tool is actuated by pressing the tool against the material to be nailed and fires a spark plug in the first cylinder. A cam connected to the shaft of the pinion gear intercoupling the two pistons, triggers a second piezoelectric igniter that fires a plug in the second cylinder to drive the impact piston and its attached hammer rod to drive one nail in a nail magazine in the end of the tool. The impacting high energy expansion stroke of the second cylinder provides the next compression stroke of the smaller first cylinder which is again fired by the next actuation of the first piezoelectric igniter.

A nail-driving tool includes a body and an illumination device detachably mounted to the body. The body includes a plurality of engaging members formed thereon, and the illumination device includes a casing having an engaging groove for releasably engaging with one of the engaging members of the body.

A combustion-engined setting tool for driving fastening elements such as, e.g., nails, bolts, pins in a constructional component includes a combustion chamber (13) for combusting an oxidant-fuel mixture, elements for closing the inlet opening (15) and the outlet opening (19) provided in the combustion chamber, ventilator (41) for generating a gas flow from the inlet opening through the combustion chamber and toward the outlet opening (19), and a combustion-energy driven drive unit (42) for driving the ventilator.

A percussion apparatus, for example for driving nails or staples, having an auxiliary piston which when released thrusts a main operating piston to an intermediate position. The auxiliary piston transfers a metered quantity of gaseous fuel together with combustion supporting air to a space between the main piston and cylinder head separating the auxiliary piston cylinder from the main piston cylinder. The explosive mixture in the space is then ignited and the main piston is thrust in a first direction displacing a driver member and simultaneously the auxiliary piston is thrust in the opposite direction to its initial position where it is retained until released to start another operating cycle; the main piston automatically returns to its initial position as the combustion gases are exhausted to the atmosphere.

A fastener applying tool is disclosed, powered by the gases produced from internal combustion of a fuel and air mixture. A piston connected to a fastener driver is slidably mounted within a cylinder to move reciprocally downwardly and upwardly through a driving and a return stroke. A combustion chamber is formed at the upper end of the cylinder. A compression chamber is formed at the lower end of the cylinder. A spark plug powered by a piezo-electric firing device, is located within the combustion chamber. The combustion chamber features a set of fan blades driven by an electric motor which is continuously in operation when the tool is in use. A main valve mechanism actuated by a set of lifting rods which are moved upwardly and downwardly when the tool is moved toward and away from the workpiece, is used to control the flow of fresh air through the combustion chamber. When the combustion chamber is isolated from the atmosphere and the fuel and air are thoroughly mixed, the spark plug is fired to explode the fuel and air mixture and force the piston through its driving stroke. The rapid discharge of combustion gases at the end of the driving stroke produces a thermal vacuum within the combustion chamber. Additional air supplied to the lower face of the piston from the atmosphere forces the piston through its return stroke.