An axle includes: an electromagnet; a transmission disc provided with a first magnetic suction member; a half shaft fitted in the transmission disc, first and second gaps being arranged circumferentially between the transmission disc and the half shaft; and a transmission assembly arranged between the transmission disc and the half shaft, and provided with a second magnetic suction member, a thickness of the transmission assembly being less than the first gap, and greater than or equal to the second gap. When the electromagnet is powered off, the transmission assembly and the half shaft are relatively stationary, and the transmission assembly is located at the first gap. When the electromagnet is powered on, the first magnetic suction member and the second magnetic suction member are attracted by the electromagnet, and the transmission disc rotates synchronously with the transmission assembly and rotates to the second gap relative to the half shaft.