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 ball balancer for minimizing a dynamic unbalance of a moving part of a rotating machine such as a centrifuge is provided. The ball balancer includes a rotary balancer casing having disposed therein balls. The rotary balancer casing is mounted on the moving part coaxially with an axis of rotation thereof and has formed therein an inner side wall which is so curved that the balls are lifted away from the bottom of the balancer casing along the inner side wall by the centrifugal force and biased toward the opposite side of an unbalanced mass of the moving part when the rotational speed of the moving part exceeds a resonant speed that is a rotational speed of the moving part when matched with a natural frequency of the moving part, thereby counterbalancing the unbalanced mass of the moving part. In an alternative form, the balls include a first group having a large diameter and a second group having a small diameter. The large-diameter balls and the small-diameter balls are arranged alternately.

Abstract: A motor and a power transmitting mechanism are accommodated and supported in a two-piece housing unit separable into first and second housings. An air tank is defined by an outer surface of the second housing and an inside surface of a third housing provided on a recessed outer surface of the second housing.

Abstract: The object of the present invention relates to reduction of noise during no-load running of a gear device and is to provide a gear shock absorbing mechanism, by which it is possible to damp collision force of tooth against tooth by simplified structure and to reduce gear noise. A driven gear is connected to a driven shaft via a radial gap, and a key connects the driven gear with the driven shaft in rotating direction via a peripheral gap, and an elastic member is compressed in axial direction and is placed between a stop washer connected with the driven shaft and the driven gear.

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.