Image is for illustration purposes only. Actual part may vary.

MSA113A

MANUAL SLACK ADJUSTER

The MSA113A is a manual slack adjuster for heavy-duty truck and trailer air brake systems. It connects the brake chamber pushrod to the S-cam shaft, converting the chamber’s pushrod motion into rotation to spread the brake shoes. Manual slack adjusters require periodic adjustment to maintain proper clearance between the brake linings and the drum. They are typically replaced when the splines become worn, the adjuster mechanism seizes, or when a fleet prefers manual control instead of automatic slack adjusters. While no exact documentation for this part number was found, similar manual slack adjusters like the Gunite AS1137 [finditparts.com] serve the same function.