Hammer drill with a mechanism for preventing inadvertent hammer blows

摘要

A hammer drill (1) includes a lock plate (35) forward of a boss sleeve (13) and a swash bearing (14) which cooperates with the boss sleeve to convert the rotation of an intermediate shaft (5) on which the boss sleeve is mounted. The lock plate is mounted on the boss sleeve and selectively engages claws (23) of the boss sleeve (13) in a manner that permits its integral rotation with and axial slide with respect to the boss sleeve. The lock plate is additionally biased in the forward direction by a coil spring (38) so that when a clutch (19) is shifted forward in a drill mode, the lock plate also moves forward into engagement with a stopper (39) secured to an inner housing (4), preventing inadvertent rotation of the boss sleeve. <IMAGE>