Electric ratchet wrench

An electric ratchet wrench comprising:

• a body including a first end and a second end, with the first end of the body including an inner periphery having a toothed portion, with the body including a connection hole, with the connection hole including first, second, and third sections arranged along a first axis, with the first section having a first inner diameter perpendicular to the first axis, with the second section having a second inner diameter perpendicular to the first axis, with the second inner diameter smaller than the first inner diameter, with the third section having two ends respectively connected to the first and second sections, with an inner wall face of the third section being at a first angle of 120° to an inner wall face of the first section;
• a ratchet device mounted to the first end of the body, with the ratchet device including a driving member, a pawl device, a first ring gear rotatably mounted around the driving member, a second ring gear rotatably mounted around the driving member, and a direction switching rod received in the driving member, with the pawl device mounted between the first and second ring gears and including two primary pawls, a first secondary pawl, and a second secondary pawl, with each of the two primary pawls pivotably mounted to the driving member and selectively meshing with the toothed portion of the body, with each of the first and second ring gears rotatable relative to the driving member in a clockwise direction or a counterclockwise direction, with each of the first and second ring gears including an inner toothed portion on an inner periphery thereof and an end toothed portion on an end face thereof, with the end toothed portions of the first and second ring gears facing each other, with the first secondary pawl selectively meshing with the inner toothed portion of the first ring gear, with the second secondary pawl selectively meshing with the inner toothed portion of the second ring gear, with the driving member including an end adapted for directly or indirectly driving a fastener, with the direction switching rod pivotable relative to the driving member between two positions respectively corresponding to a driving direction and a non-driving direction, wherein when the direction switching rod pivots between the two positions, an engagement status between each of the two primary pawls and the toothed portion of the body and an engagement status between the first and second secondary pawls and the first and second ring gears are changed to provide a direction switching function;
• a power device received in the second end of the body, with the power device including a motor and a power source, with the motor including a motor shaft, with the power source electrically connected to the motor for driving the motor shaft;
• and
• a transmission device including a transmission shaft, a bevel gear, and a first elastic element, with the transmission shaft rotatably received in the connection hole and including a connection portion having a first end coupled with the motor shaft of the motor, with the connection portion having a first outer diameter perpendicular to the first axis, with the transmission shaft further including a second end with a transmission portion, with a shoulder connected between the transmission portion and the connection portion, with the shoulder having a second outer diameter perpendicular to the first axis, with the second outer diameter smaller than the first outer diameter, with the connection portion having a conical face connected to the shoulder, with the conical face of the connection portion at a second angle of 120° to an outer face of the shoulder, with the bevel gear mounted around the transmission portion and movable along the transmission shaft to selectively mesh with or disengage from the end toothed portions of the first and second ring gears, with the first elastic element mounted between the shoulder and the bevel gear, with the first elastic element mounted around the transmission portion of the transmission shaft and biasing the bevel gear to mesh with the end toothed portions of the first and second ring gears;
• wherein when the bevel gear meshes with the end toothed portions of the first and second ring gears and when the motor shaft of the motor drives the transmission shaft and the bevel gear to rotate, the bevel gear drives the first and second ring gears to respectively rotate in the clockwise direction or the counterclockwise direction relative to the driving member, the two primary pawls and one of the first and second secondary pawls actuate the driving member to rotate to thereby rotate the fastener;
• and
• wherein a resistance larger than a torque outputted by the motor shaft is encountered at a position while driving the fastener and causes a tooth slippage phenomenon in which the bevel gear repeatedly engages with and disengages from the end toothed portions of the first and second ring gears, the body can be manually rotated to overcome the resistance and to forcibly drive the fastener through the position at a moment the bevel gear engages with the end toothed portions of the first and second ring gears, and the bevel gear reengages with the end toothed portions of the first and second ring gears after the fastener passes through the position.