The insulating sleeve of the motor parts is completely free from cracks and looseness. The lead connections should be strong and the insulation resistance should not be less than 0.5 MΩ at an operating temperature of 75 °C. In the brush device, the lower edge of the brush box is required to be 2~4mm away from the surface of the motor fitting. If the distance is too large, the brush will jump in the brush box. If it is a hard brush, it is likely to be broken. The brush should be slidably flexible in the brush box, and the inner surface of the brush box is smooth. The radial dimension tolerance of the inner hole of the brush box is H10, and the axial dimension tolerance is H8. Brush width and thickness dimension tolerance d11. The gap between the brush and the brush box should be 0.1~0.2mm, the gap is too large, the brush will produce tangential oscillation in the brush box, affecting the normal operation of the motor parts; the gap is too small, so that the brush is stuck in the brush box, causing similar The arc of the electric arc burns the surface of the copper ring.

During the overhaul, the motor parts should be carefully inspected: whether the motor parts work surface is smooth, with or without burn marks, streaks and other defects. The working surface is required to be smooth and there should be no rust and grease. The outer parts of the motor parts are to be properly bundled and sealed. If it is not handled well, it can be bundled with a non-woven glass ribbon impregnated with synthetic resin to prevent the outer leakage of mica flakes during motor operation. The fitting of the motor parts and the shaft and the matching of the rings and the insulating sleeve should be firm. Use a small hammer to tap the copper ring and the copper joint, and there should be metal sound.