For the ASR (anti-spin regulator) system, which reduces a driving wheel slip, the valve inside the unit is made of an unsuitable material and its measurement is inappropriate, and therefore, the valve may deteriorate over time due to the air pressure from behind and deform under a high temperature circumstance, and it may eventually block the pressure relief port. If this occurs, the pressure in the brake pipe will remain and the brake will be kept activated, which can cause the brake drums to overheat. In the worst case, a fire could break out.
