Trigger lock-on lock-off mechanism

1. A trigger mechanism for a power tool comprising:

a trigger defining an interior portion, the trigger including a rib extending from the interior of the trigger, the trigger being moveable in a first direction to move the trigger to an ON position, the trigger being movable in a second direction to move the trigger to an OFF position;

an electrical switch for activation by movement of the trigger between the ON and OFF positions to close and open an electrical circuit; and

a locking mechanism defining a recess and an opening, the locking mechanism moveable by the user in a third direction to unlock the trigger from the OFF position and being moveable by the user an additional distance in the third direction to receive the rib at least partially within the recess and to receive a portion of the trigger within the opening to lock the trigger in the ON position.

2. The trigger mechanism of claim 1 wherein the locking mechanism is configured so that as the user pushes a first end of the locking mechanism in the third direction, a second end of the locking mechanism enters the aperture.

3. The trigger mechanism of claim 1 wherein the locking mechanism selectively prevents the trigger from moving to the ON position.

4. The trigger mechanism of claim 3 wherein the locking mechanism has an opening thereon, a portion of the trigger passing into the opening when the locking mechanism is moved in the third direction and the trigger is moved in the first direction.

5. The trigger mechanism of claim 1 wherein the trigger is moveable in the first direction to unlock the trigger from the ON position.

6. The trigger mechanism of claim 5 further comprising a biasing member, the biasing member being configured to bias the trigger towards the OFF position.

7. The trigger mechanism of claim 6 wherein the biasing member is coupled to the electrical switch.

8. The trigger mechanism of claim 6 wherein the locking mechanism includes a second biasing member to bias the locking mechanism in a fourth direction, the fourth direction being opposite to the third direction.

9. A method of locking a trigger for a power tool in an ON position comprising:

providing a trigger, including a rib extending from an interior of the trigger, the trigger being movable in a first direction to move the trigger to the ON position and in a second direction to move the trigger to the OFF position;

moving a locking mechanism in a third direction to unlock the trigger from the off position, the locking mechanism defining a recess and an opening;

moving the trigger in the first direction to place the trigger in the ON position;

holding the trigger in the ON position;

moving the locking mechanism an additional distance in the third direction to place the locking mechanism in a locked-on position wherein at least a portion of the recess receives the rib, and the opening receives a portion of the trigger;

holding the locking mechanism in the locked-on position; and

releasing the trigger and the locking mechanism so that the locking mechanism holds the trigger in the ON position.

10. The method of claim 9 further comprising biasing the locking mechanism in a fourth direction using a biasing member, wherein the fourth direction is opposite of the third direction.

11. The method of claim 9 further comprising moving the trigger in the first direction to release the locking mechanism from the locked-on position.

12. The method of claim 11 further comprising biasing the trigger in the second direction using a biasing member.

13. A power tool comprising:

a housing including a first half and a second half, the first half and the second half are defined by a horizontal plane through the housing;

a motor disposed in an interior portion of the housing;

a working element selectively driven by the motor;

a trigger disposed on the first half of the housing, the trigger pivotally coupled to the housing and having an aperture formed as part of an internal portion thereof, the trigger being pivotable in a first direction to move the trigger to an ON position, the trigger being pivotable in a second direction to move the trigger to an OFF position;

an electrical switch selectively activated by the pivot movement of the trigger between the ON and OFF positions to turn the motor ON and OFF; and

a locking mechanism adjacent the trigger and disposed on the first half, the locking mechanism moveable by the user in a third direction to unlock the trigger from the OFF position and being moveable by the user an additional distance in the third direction to position a portion of the locking mechanism into engagement with the aperture to lock the trigger in the ON position.

14. The power tool of claim 13 , wherein the locking mechanism is configured so that as the user pushes a first end of the locking mechanism in the third direction, a second end of the locking mechanism enters the aperture.

15. The power tool of claim 13 wherein the locking mechanism selectively prevents the trigger from moving to the ON position.

16. The power tool of claim 13 wherein the working element is an abrasive disc.

17. The power tool of claim 13 wherein the trigger is moveable in the first direction to unlock the trigger from the ON position.

18. The power tool of claim 17 further comprising a biasing member configured to bias the trigger towards the OFF position.

19. The power tool of claim 18 wherein the biasing member is coupled to the electrical switch.

20. The power tool of claim 18 wherein the locking mechanism includes a biasing member to bias the locking mechanism in a fourth direction, the fourth direction being opposite to the third direction.