Vibration reduction apparatus for power tool and power tool incorporating such apparatus

摘要

A vibration reduction apparatus 501 for use with a hammer tool having a hammer piston 520. The hammer piston 520 is caused to reciprocate in cylinder 530 by rotation of a gear wheel 523 about axis 524, the hammer piston 520 being mounted to the gear wheel 523 via the piston arm 531 and pivot pin 522. Reciprocation of the hammer piston 520 causes a flying mass 569 to be driven along cylinder 530 to impart a hammer action to a bit of the tool. The gear wheel 523 is caused to rotate by meshing of gear 514 on drive shaft 511 being rotated by a motor. A cam 533 is mounted around gear wheel 523, a counterweight 521 surrounds piston cylinder 530 which includes a cam follower 534. The cam follower and cam 534, 533 are urged into contact by means of compression spring 535. The external profile of the cam 533 is such that rotation of the gear wheel 523 to causes reciprocation of hammer piston 520 and oscillation of counterweight 521 in antiphase to each other to counteract vibrations produced by operation of the hammer action of the tool.