Hammer Drill

A hammer drill (1) comprises a motor (9) including a motor output shaft (11), a hollow spindle (13), a hammer mechanism comprising a piston (17) arranged for reciprocating motion within the hollow spindle (13), and an intermediate shaft assembly (23) rotationally engaged with the motor output shaft (11). The intermediate shaft assembly (23) comprises a first part (25), a second part (27)and a connecting part (29). The first part (25) carries a first gear (31) which is in engagement with a second gear (35) on the hollow spindle (13) to cause rotation of the spindle (1). The second part (27) carries a crank member (37) arranged to cause the reciprocating motion of the piston (17). The connecting part (29) is arranged for movement with respect to the first and second parts (25, 27) to rotationally interconnect, or disconnect, the first and second parts (25, 27). In a first position of the connecting part (29) only one of the first and second parts (25, 27) is rotationally engaged with the motor output shaft (11) to enable rotation of only one of the first gear (31) and the crank member (37) respectively. In a second position of the connecting part (29) both of the first and second parts (25, 27) are rotationally engaged with the motor output shaft (11) to enable rotation of both the first gear (31) and the crank member (37).