POWER TOOL

摘要

PROBLEM TO BE SOLVED: To avoid limitation in design when multi-speed transmission of three or more speeds is to be attained and improve freedom in setting a transmission gear ratio. SOLUTION: A power tool can switch as to whether respective ring gears 14 and 19 of two planetary decelerators 1 and 2 are made unable to rotate or the gears can rotate integrally with other members while coupled with the members constituting the planetary decelerators. A switching member 15 unable to relatively rotate with the ring gear 14 of one planetary decelerator 1 of the two decelerators and capable of relatively moving in the axial direction is provided and can engage with the other member 13 by axial movement of the switching member. The other planetary decelerator has its ring gear 18 axially movable to enable the ring gear to engage with the other member. A ring integrally rotating with one of the ring gears is moved without axially moving the ring gear, thereby changing over a deceleration ratio. COPYRIGHT: (C)2009,JPO&INPIT