How can you check the slack adjuster for movement?

The correct method to check the slack adjuster for movement involves applying a significant amount of force to it, which is achieved by pulling hard on each slack adjuster. This method is essential because it allows the driver or mechanic to determine whether the slack adjuster is functioning properly and if it has the appropriate amount of play within the braking system. A slack adjuster that does not move as it should may indicate problems with the air brake system, such as a need for adjustment or potential malfunctions that could lead to brake failure.

Other methods may not provide an accurate assessment of the slack adjuster's condition. For instance, simply swiping it with your hand would not exert enough force to gauge its functionality. Observing it while braking might provide some visual feedback, but without physical manipulation, it's difficult to ascertain whether the slack adjuster is properly adjusting itself in relation to brake wear. Using a wrench to tighten it could possibly lead to misadjustments or further issues, as the slack adjuster is designed to adjust automatically based on brake wear. Therefore, manually pulling on the slack adjuster is the most effective way to check for movement and ensure the air brake system is operating correctly.