Mode changing mechanism for use in a hammer drill

A hammer drill having a plurality of selectable operating modes, comprising:

• a motor;
• a housing;
• an intermediate shaft having a longitudinal axis and supported within the housing for being rotated upon activation of the motor;
• a rotation transmitting member freely rotatably provided on the intermediate shaft and slidable along the longitudinal axis of the intermediate shaft, the rotation transmitting member, when rotated, transmitting rotation of the motor to a tool bit attached to the hammer drill;
• a strike transmitting member freely rotatably provided on the intermediate shaft, the strike transmitting member, when rotated, converting the rotation of the motor into hammer blows and transmitting the hammer blows to the tool bit;
• a clutch member integrally rotatable with the intermediate shaft and slidable along the longitudinal axis of the intermediate shaft between the rotation transmitting member and the strike transmitting member;
• a first switchover device for being externally operable to slide at least one of the clutch member and the rotation transmitting member;
• and
• a second switchover device interlocked with the first switchover device to slide the other one of the clutch member and the rotation transmitting member which is not slid by the first switchover device,
• wherein the engagement status of the clutch member with the rotation transmitting member and with the strike transmitting member is changeable by operation of the first switchover device so as to select the operation mode of the hammer drill from a rotation-only mode, a rotation-plus-hammer mode, and a hammer-only mode, and in the hammer-only mode, the rotation transmitting member is movable between a free-rotation position in which the rotation transmitting member is permitted to rotate and a lockup position in which the rotation transmitting member is prevented from rotation by one of the first and second switchover devices.