A power apparatus includes: an input shaft; an output shaft; a connecting mechanism; a first driving mechanism; a second driving mechanism of which an output end is fixedly connected with the input shaft; a first transmission component sleeved on the input shaft; a second transmission component sleeved on the output shaft; a third transmission component sleeved on the input shaft; a fourth transmission component sleeved on the output shaft; a changeover mechanism causing the first transmission component to rotate with rotation of the input shaft, the first transmission component rotating to drive the second transmission component to rotate, the output shaft rotating with the rotation of the second transmission component; or causing the third transmission component to rotate with rotation of the input shaft, the third transmission component rotating to drive the fourth transmission component to rotate, the output shaft rotating with the rotation of the fourth transmission component.