• Apply the brakes and check that the slack adjusters rotate freely without binding.
• Release the brakes and check that the slack adjusters return to their released position without binding.
• With brakes released, check that the angle formed by the slack adjuster arm and push rod is greater than 90° (Fig. 52). All slack adjusters should be adjusted to this same angle.
• With brakes applied (20 psi [138 kPa]), check that the new angle is no less than 90° and that all slack adjusters have the same amount of travel.

Note: The practical test will include proper adjustment of a manual slack adjuster and a verbal explanation of the proper procedure for adjusting an automatic slack adjuster.