What can cause the brakes to drag in an air brake system?

In an air brake system, the dragging of brakes is primarily caused by improper adjustment or malfunctioning slack adjusters. Slack adjusters are mechanical devices that link the brake chamber to the brake shoes, and their primary purpose is to ensure that the brakes are applied effectively and consistently. When slack adjusters are not properly maintained or adjusted, they can fail to allow the brake shoes to retract fully when the brakes are released. This failure results in the brakes continuing to make contact with the brake drum or rotor, which generates heat and leads to premature wear and decreased efficiency.

Having slack adjusters that are either too loose or too tight can also contribute to this issue. If they are too tight, they might not allow the brake shoes to disengage fully, while if they are too loose, the system may not apply enough force, potentially causing irregular braking performance. Regular maintenance and adjustments of slack adjusters are essential to ensure that the brakes operate as they should, preventing dragging and ensuring safety on the road.