Abstract: A duplex saw, including a machine head assembly of which a top portion is mounted with a cutting working platform, a base, a rotating disk, and a machine head rotating seat positioned between the machine head assembly and the rotating disk and hinged with the machine head assembly and the rotating disk. The machine head assembly includes a motor, a machine frame, a gear box body, a transmission mechanism and a saw blade. The motor is fixed on the machine frame. The transmission mechanism is provided in the gear box body and constitutes a gear box assembly. A gear shaft of the motor drives the transmission mechanism. The gear box assembly can be rotated about the gear shaft of the motor. The blade is fixed on an output shaft of the transmission mechanism, the output shaft and the gear shaft of the motor are parallel to each other.

Abstract: An electric drill forward and reverse rotation automatic switching apparatus includes: a gearbox, a first-stage gear, a first-stage gear shaft, a second-stage gear, a second-stage gear shaft, a transition gear, a transition shaft, a third-stage gear, and an output shaft. The first-stage gear is fixed on the first-stage gear shaft. The second-stage gear is fixed on the second-stage gear shaft. The first-stage and second-stage gear shafts are disposed on the gearbox housing. The transition gear is disposed on the transition shaft which is fixed on the gearbox housing. The output shaft is disposed on the gearbox housing. The third-stage gear is sleeved on the output shaft and disposed on the gearbox housing. The first-stage gear shaft engages with the second-stage gear and the transition gear simultaneously. The transition gear engages with the third-stage gear. The second-stage gear shaft and the output shaft are on the same axis.