Patent ID: 6953137

Claim:
A fastener driving tool for driving a fastener into a workpiece, comprising: a main driving section comprising a main housing, and a drive bit movable in a first direction toward the workpiece and in parallel with an extending direction of the drive bit and movable in a second direction opposite to the first direction; a trigger mechanism pivotally movable in an operating direction and a non-operating direction and supported to the main housing; a contact arm movable toward its top dead center position in the second direction and toward its bottom dead center position in the first direction, the contact arm having a free end portion and a trigger associating portion associatable with the trigger mechanism; a contact arm spring for biasing the contact arm in the second direction; and, a switch mechanism comprising: a plunger movable between OFF position where driving movement of the drive bit is prohibited and ON position where driving movement of the drive bit is permitted, the plunger being abuttable on the trigger mechanism and movable to the ON position by the movement of the trigger mechanism in the operating direction; and a plunger spring biasing the plunger toward the OFF position, the plunger spring providing a biasing force greater than that of the contact arm spring, the trigger associating portion being lockingly engaged with the trigger mechanism at least when the contact arm is positioned at its top dead center and when the trigger mechanism is moved to its operating direction, and the trigger associating portion becoming disengaged from the trigger mechanism when the contact arm moves toward the first direction thereby enabling the contact arm to be moved toward the top dead center by the biasing force of the contact arm spring.