Patent ID: 6666284
Filing Date: 2003-12-23
Classification: B25D

Abstract:
A rotary hammer, which comprises:an intermediate shaft (24) which is rotatably driven by a motor of the rotary hammer when power is supplied to the motor; a spindle (18) which can be driven in rotation about its axis by the intermediate shaft 24 through a spindle drive arrangement (62,64); a tool holder (16) arranged for rotation with the spindle (18) for releasably holding a bit or a tool such that the bit or tool can reciprocate; a pneumatic hammering arrangement (20,21,22) located within the spindle (18) which can repeatedly impact the bit or tool held within the tool holder (16); said pneumatic hammering arrangement comprising a piston (20) which can be reciprocally driven by a hammer drive arrangement (34,36,38,39,40,42) which can translate rotary drive from the intermediate shaft (24) to a reciprocating drive to the piston (20); and a mode change mechanism for changing the operation of the rotary hammer to operate in any of three modes, a rotary drive only mode, a hammer only mode or a rotary hammer mode; said mode change mechanism comprising: a single actuator (8) switchable by a user of the rotary hammer amongst the three modes of operation; a spindle driving member (56) rotatable on the intermediate shaft (24) for driving the spindle drive arrangement (62,64); a hammer driving sleeve (34) rotatable on the intermediate shaft (24) for driving the hammer drive arrangement (34,36,38,39,40,42); and a mode change sleeve (52) which is permanently driven by and shiftable along the intermediate shaft (24); where, upon the switching of the actuator (8) by a user, shifts the mode change sleeve (52) along the intermediate shaft (24) amongst the three modes positions, such that in a first rotary drive only position the mode change sleeve (52) transmits rotary drive to the spindle driving member (56) to transmit rotary drive to the spindle drive arrangement (62,64), in a second hammer only position the mode change sleeve (52) transmits rotary drive to the hammer driving sleeve (34) to transmit rotary drive to the hammer drive arrangement (34,36,38,39,40,42), and in a third rotary hammer position the mode change sleeve (52) transmits rotary drive to the spindle driving member (56) and to the hammer driving sleeve (34) to transmit rotary drive to the spindle drive arrangement (62,64) and to the hammer drive arrangement (34,36,38,39,40,42).