目前,我国使用的大部分车辆,包括国产和进口车,其制动鼓在使用一段时间后,内孔形成里大外小的台阶(见附图a),原因是制动鼓内孔距外缘2～6mm处不和制动蹄衬片接触,而接触处则因与衬片不断摩擦而磨损,且为保证制动可靠,又需不断调正制动间隙,以致磨损后的孔径连续扩大,而其边 At present, most of the vehicles used in our country, including domestic and imported vehicles, have been used for a period of time after their brake drums have been used. Edge 2 ~ 6mm at the brake shoe lining contact, and contact with the lining due to friction and wear and tear, and to ensure reliable braking, but also need to constantly adjust the brake clearance, resulting in continuous expansion of the aperture after wear , While its edge