One, uniform excessive wear

Due to the large brake resistance, brake imbalance and dust impurities into a series of reasons resulting in rapid and uniform wear of the brake drum. A very distinct ring of steps is formed at the edge of the brake drum.

Two, unilateral abnormal wear

Sometimes it is found that the inner round surface of the brake drum has obvious wear marks on one side and no obvious wear marks on the other side.

This is due to the brake drum and brake caused by different centers, further analysis, because the brake drum and hub are rigidly connected coaxial rotation, if there is no abnormal phenomenon in the hub, the brake drum and hub at the same time eccentric rotation is less likely.

Then it is necessary to consider the installation accuracy of the brake shoe more, and to check the brake floor, brake support plate, brake shoe pin and other parts one by one.

Three, uniform hot crack

Due to the heavy truck long time down the slope, the brake drum heat capacity is insufficient, resulting in the formation of uniform and meticulous turtle crack on the friction surface, turtle crack will continue to spread, lengthening, deepening. When the turtle crack length increases to 30 ~ 40mm, it needs to be replaced in time, otherwise it is easy to form brake drum cracking and other serious faults affecting the normal use of the vehicle.

Four, local hot (black) spots

When the brake drum is heated unevenly, it may produce local hot (black) spots, some neatly cover the friction surface of the brake drum, forming a uniform parallel ring, and some will appear in a larger local area or form a uniform distribution of small round spots.

This is mainly due to the uneven wear caused by the errors in the material and structure of the brake drum. When the above spots are obvious, the brake drum needs to be replaced in time.

Five, brake drum pulling groove

Slot is refers to the brake drum inside the circumference of the working face to form a deep notch or grooving depression, depth is greater than 2.5 mm, width is greater than 0.8 mm, this is due to the friction plate abnormal wear caused by rivet exposure, rivets and other sharp objects in the brake drum inside the circumference of the working face to form a slot. The brake drum and friction plate need to be replaced at the same time.

Six, brake drum blue

The inner circumferential working surface of the brake drum is blue. At this time, the brake drum and brake are likely to have been damaged or deformed. Because the blue color of the brake drum proves that it generates extremely high temperatures during operation. At this time, the relevant parts need to be carefully checked and analyzed, and the failed parts should be completely replaced.

Seven, brake drum bottom

The brake drum is connected to the wheel hub by a ring of flange bolts (also wheel bolts), through which braking force generated by the brake drum is transferred to the wheel hub to limit wheel rotation.

Brake drum bottom is refers to the brake drum circumference working part (cylinder) and flange part (disc) off, resulting in brake failure, mainly due to the brake drum in the production process of improper structure and material factors.

Eight, brake drum bolt hole wear

Brake drum bolt hole wear, usually because the flange bolts (wheel bolt) not fully tighten, relative wheel brake drum radial and axial occur relatively dynamic impact, lead to abnormal wear of brake drum bolt hole deformation, wheel bolt, wheel hub and related parts and components will be irreversible serious fault occurs, the need for related spare parts for all replacement.

Nine, wheel hub grease pollution

When the wheel hub oil seal failure, lubricating oil/grease was dumped the circumference of a circle on the working plane to the brake drum, face serious pollution, and still not handled in time, the lubricating oil/grease will further infiltration within the brake drum circumferential face, it's hard to reverse damage, because oil/fat actually has penetrated into the brake drum.

At this time, the working friction pair formed by the inner surface of the brake drum and the friction plate has been broken, which is prone to safety failure of the vehicle. Therefore, the brake drum needs to be replaced immediately.