Hammer drill

1. A hammer drill comprising:

a motor;

an electrical power circuit arranged to provide power to the motor;

a tool holder arranged to hold a cutting tool;

a drive transmission, operable in at least two modes of operation, wherein, when a cutting tool is held by the tool holder, the drive transmission is operable to convert the drive output of the motor into a rotary drive for the cutting tool in a drilling mode of operation and repetitive impacts imparted to the cutting tool in a hammer mode of operation;

a controller configured to control an operation of the motor, wherein the motor is prevented from operating when no power is provided to the controller;

a lock-on mechanism engageable by a user to enable a continuous operation of the motor;

a mode change mechanism configured to switch the drive transmission between at least the hammer mode of operation and the drill mode of operation; and

an electrical power circuit configured to provide power to the controller, the electrical power circuit comprising a first power switch and a second power switch arranged along a current path to the controller, each of the first power switch and the second power switch being configured to allow passage of power in a closed state but prevent passage of power in an open state,

wherein the lock-on mechanism is configured to interface the first power switch, and wherein the mode change mechanism is configured to cause the second power switch to be opened in the drill mode of operation but closed in the hammer mode of operation so as to provide power to the controller when the lock-on mechanism is active in the hammer mode of operation, but not when the lock-on mechanism is active in the drill mode of operation wherein the first power switch and the second power switch are provided in parallel along the current path to the controller.

2. The hammer drill of claim 1 , wherein the lock-on mechanism, when moved to a locked position, is configured to lock the first power switch in the open state.

3. The hammer drill of claim 2 , wherein the lock-on mechanism includes a slider biased via a spring to engage the first switch and place the first power switch in the closed state, the slider being moveable into the locked position against a biasing force of the spring.

4. The hammer drill of claim 1 , further comprising at least one electrical switch located within the electrical power circuit to provide power to the motor, wherein the electrical switch provides power to the motor in a closed state and prevents power being provided to the motor in an open state.

5. The hammer drill of claim 4 , wherein the at least one electrical switch and at least one of the first power switch or the second power switch have to be closed to power the motor.

6. The hammer drill of claim 1 , wherein the motor is a brushless motor;

wherein the controller is configured to control commutation of the motor when it is being powered;

wherein the controller ceases to control the commutation of the motor when no power is provided to the controller, preventing the motor from being operated.

7. The hammer drill of claim 1 , wherein the drive transmission is operable to convert the drive output of the motor into both the rotary drive and the repetitive impacts in a combined hammer and drill mode of operation.

8. The hammer drill of claim 7 , wherein the mode change mechanism is configured to cause the second power switch to be opened in the combined hammer and drill mode of operation to prevent supply of power to the controller when the lock-on mechanism is active in the combined hammer and drill mode of operation.