Abstract: Disclosed is an electric power tool having a gear mechanism, which reduces a noise by absorbing collision of gears and is resistible to a high torque. A power transmission key 7 composed of high-strength plastic is provided between an output shaft 3 and a gear 4, and a plane or a V-groove is formed on each of the output shaft 3 and the gear 4 contacting the power transmission key 7.

Abstract: Disclosed is an electric power tool having a gear mechanism, which reduces a noise by absorbing collision of gears and is resistible to a high torque. A power transmission key 7 composed of high-strength plastic is provided between an output shaft 3 and a gear 4, and a plane or a V-groove is formed on each of the output shaft 3 and the gear 4 contacting the power transmission key 7.

Abstract: Disclosed is an electric power tool having a gear mechanism, which reduces a noise by absorbing collision of gears and is resistible to a high torque. A power transmission key 7 composed of high-strength plastic is provided between an output shaft 3 and a gear 4, and a plane or a V-groove is formed on each of the output shaft 3 and the gear 4 contacting the power transmission key 7.

Abstract: Disclosed is an electric power tool having a gear mechanism, which reduces a noise by absorbing collision of gears and is resistible to a high torque. A power transmission key 7 composed of high-strength plastic is provided between an output shaft 3 and a gear 4, and a plane or a V-groove is formed on each of the output shaft 3 and the gear 4 contacting the power transmission key 7.

Abstract: A percussion hammer tool comprises a spindle 1 causing rotation about an axis thereof. The spindle 1 is driven by a motor M. A hammer 3, slidably coupled with the spindle 1, generates a percussion force to rotate and hit an anvil. The anvil is divided into an engaging portion 7 engageable with the hammer 3 and a tip tool holding portion 8 holding a tip tool 16. The engaging portion 7 and the tip tool holding portion 8 are locked with each other. A torque transmitting mechanism 11 makes the engaging portion 7 and the tip tool holding portion 8 displaceable with each other telescopically in an axial direction. A cushion member 10 is provided in a clearance 9a between the engaging portion 7 and the tip tool holding portion 8, thereby transmitting an angular component of the percussion force while absorbing an axial component of the percussion force. An additional cushion member 13 may be interposed between the spindle 1 and the anvil.

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.