A slack adjuster's free play needs to be adjusted if it exceeds how much when pulled hard on?

The indication that the slack adjuster's free play should be adjusted if it exceeds one inch when pulled hard on is based on industry standards for maintaining effective braking systems. A slack adjuster is a crucial component in the air brake system, as it is responsible for maintaining the proper tension on the brake shoes against the brake drum.

A maximum free play of one inch ensures that there is sufficient engagement between the brake shoes and the drum to provide effective stopping power when needed. If the free play exceeds this measurement, it could lead to reduced braking efficiency, increased stopping distances, and potential safety hazards for the vehicle and its passengers. Therefore, monitoring and adjusting the slack adjuster is essential for ensuring that the air brake system operates correctly and safely.