Brake Systems - DELCO-Moraine Automatic Adjuster: Operation

Automatic adjusters operate only when brakes are applied as car is moving in reverse. The link, which holds top of actuating lever stationary, forces lever to pivot on secondary shoe. This pivoting action forces pawl downward against tooth on adjuster screw. If the lining-to-drum clearance is correct, the downward movement will stop before adjusting screw is turned. If clearance is too wide, secondary shoe will move outward. This allows pawl to move down enough to turn adjuster screw one notch. This brings lining-to-drum clearance back to correct specifications. If adjuster screw is frozen or clearance is too great, an override device will prevent adjuster movement. This will prevent binding of automatic adjuster linkage.