Abstract: An actuating device for an electrical power wrench includes a base member connected to a motor and an output shaft is rotatably connected to the base member. A pin biased by a spring movably extends through the base member. A ball biased by a spring is received in the base member and engaged with a groove defined in an outside of the pin. A movable frame with a weight movably retained between two blocks on the base member and two springs connected between the two ends of the movable frame and the two blocks. An L-shaped actuating member is rotatably connected between the two blocks and pivotably connected to two lugs of the movable frame. When the base member is rotated by the motor, the movable frame radially moves due to the eccentric force to pivot the actuating member. When the force being put on to the pin by the actuating member overcomes the froce of the two springs, the pin extends to impact a plate extending radially outward from the output shaft to output a sudden and large torque.

Abstract: An actuating device for an electrical power wrench includes a base member connected to a motor and an output shaft is rotatably connected to the base member. A pin biased by a spring movably extends through the base member. Two blocks extend from a side of the base member and located in opposite to the output shaft. A movable frame with a weight movably retained between the two blocks and two springs connected between the two ends of the movable frame and the two blocks. An L-shaped actuating member is rotatably connected between the two blocks and connected to two lugs of the movable frame so that when the base member is rotated by the motor, the movable frame radially moves due to the eccentric force so as to pivot the actuating member. The pivotal movement of the actuating member pushes the pin to extend from the other side of the base member to impact a plate extending radially outward from the output shaft. The output shaft outputs sudden and large torque.