Cause Analysis of Auto Brake Drum Failure

As an important safety protection component of auto, the brake drum of auto is the main detection and maintenance target in the daily management and maintenance of auto. According to the summary of daily maintenance, the failure of brake drum mainly includes: cracking, bottoming, excessive wear, cracking, abnormal Common problems such as worn casting failures.
Failure Analysis of Brake Drum Cracks
The auto brake drum will be affected by many forces during normal operation, one is the normal pressure from the shoe, and the other is the tangential force generated by the rotation and the shoe clutch. When the normal pressure is removed, the tangential force between the brake drum and the shoe clutch plate does not exist; the friction between the brake drum and the clutch plate generates a lot of heat, which causes the temperature of the brake drum to rise, while the clutch plate and the brake plate The friction of the moving drum is actually a spot contact, and the heat generated by the friction on the contact surface causes a phase change in the tissue at the contact surface, resulting in phase change stress, which reduces the thermal fatigue resistance of the place; the phase change stress will lead to braking. The phenomenon of uneven force on the drum will cause regular cracks in the brake drum under the frequent braking load of the automobile brake drum. Since the cracks are not completely parallel to the axis of the brake drum, as the cracks continue to extend, the cracks are cross-connected to form a network, which is commonly referred to as cracks, and severe cracks cause cracks. On the other hand, the gray iron brake drum undergoes a phase change under working conditions. The phase transition of the internal structure is mainly affected by temperature changes. The maximum temperature generated by the brake drum during operation can reach 800°C-950°C.
Enough to cause tissue phase transformation.
Failure Analysis of Brake Drum Cracking
The cracking of the brake drum also covers two reasons. First, the brake drum will be affected by the difference in material strength and cause the cracking problem. Second, after the cracking problem of the brake drum occurs, the interaction between the thermal stress and the phase change stress of the brake drum Local phase transformation will also occur under the condition, causing the strength to decrease. At this time, the cracks on the braking surface will continue to extend and expand, resulting in cracking. Another situation is that due to the unreasonable assembly and cooperation during the assembly of parts, local stress concentration is caused, and the frequent action of this stress causes the fracture and failure of this part.
Failure Analysis of Brake Drum Bottom Drop
On the premise that there is no crack in the auto brake drum, if there is a direct crack, this is the failure of the bottom, which will lead to the direct failure of the brake drum. Specifically, it also includes two points: one is that the strength of the brake drum material itself is poor; the other is that the brake drum is cracked under unreasonable and abnormal external force. Torsional force, which is transmitted to the wheel through the bolt connection to act as a brake for the vehicle. When the torsional force exceeds the strength that the material can bear, cracks and cracks appear on the flange of the brake drum, and even the bottom falls off.
Excessive wear and non-wear failure analysis
Excessive wear and abnormal wear can easily lead to complete failure of the automobile brake drum. First of all, excessive wear means that the inner diameter of the brake drum is getting smaller and smaller under the influence of frequent braking force. Larger, the wall thickness is getting thinner and thinner, which directly has a negative impact on the braking effect of the brake drum. Looking at abnormal wear and tear failure again, when the working surface of the brake drum is under the external force of hard objects such as shoes, grooves will appear due to frictional contact, which is often caused by unreasonable riveting of the friction plate, to a certain extent It is also caused by insufficient hardness of the auto brake drum.
To sum up, there are various reasons for the crack failure of the auto brake drum. It is generally produced by the working surface of the brake belt. With the increasing intensity of the braking work, cracks will appear on the braking surface. Causes the auto brake drum to fail.