Patent ID: 7594599

Claim:
A hand-held power tool, the operational power of which is provided by a gas combustion mechanism, said gas combustion mechanism comprising a first priming cylinder having a first piston and an air intake valve, the priming cylinder being fluidally connected via a transfer valve to a combustion chamber that is connected to a second delivery cylinder including a second piston, wherein in use, said first piston is arranged to compress air and transfer the compressed air to said combustion chamber via said transfer valve, and said first piston is activated for more than one cycle before the compressed air is transferred to said combustion chamber, and said first piston is arranged to compress air to such a degree so as to impart a pressure in the combustion chamber of at least 0.3 bar, said combustion chamber is arranged to receive said compressed air, from the priming cylinder, and fuel gas from a fuel supply port, the air and fuel gas being mixed to form an air/fuel gas mixture therein, the combustion chamber and the second delivery cylinder being arranged so that said air/fuel mixture is ignited within the combustion chamber to impart motion onto said second piston and to facilitate the operation of the tool, wherein a mechanism movable between a first and a second position includes a latching means for engaging said second position, such that said air/fuel gas mixture is further compressed by said second piston as said mechanism is moved from said first to said second position with said latching means engaged and wherein the downward force from the ignition of said air/fuel mixture overcomes said latching means and imparts motion to said second piston.