Are you supposed to adjust automatic slack adjusters?

1. Design intention: Prohibit conventional manual adjustment
Core principle: The purpose of automatic slack adjuster is to replace manual intervention. Its internal mechanism (ratchet, screw or hydraulic valve) automatically detects and compensates for wear clearance during each braking/release cycle.
The consequences of forced adjustment: If the adjustment bolt or reset mechanism is unscrewed without authorization, it will damage the preset compensation benchmark, resulting in overcompensation (brake drag) or overcompensation (excessive clearance).

2. Exception: Maintenance reset operation
Initialization after major overhaul: After replacing the friction pads (such as brake pads), it is necessary to perform a reset operation according to the manufacturer's specifications (such as using a special tool to retract the adjuster push rod), so that the new component obtains the correct initial clearance.
Calibration after stuck repair: If the adjuster gets stuck due to contamination or rust, it needs to be restored to automatic compensation function through a specific process (such as manually rotating the adjusting gear several times) after cleaning and lubrication.

3. Emergency intervention for fault states
Extreme wear alarm: When the wear reaches its limit and triggers a mechanical/electronic alarm, the adjuster is unable to continue compensating. At this point, the friction material must be replaced instead of adjusting the adjuster itself.
Automatic function failure: If it is confirmed that the internal mechanism of the adjuster is damaged (such as broken teeth or rusted screws), the entire component needs to be replaced. Temporary manual adjustment is a dangerous behavior and is only allowed for moving the vehicle to a repair point.

4. Deep reasons for strictly prohibiting manual adjustment
Breaking the dynamic balance: Manual adjustment will overwrite the memory position of the automatic mechanism, causing it to misjudge the current slack state, and the subsequent automatic compensation logic will be completely confused.
Triggering chain failures: For example, in pneumatic braking systems, incorrect adjustments may cause the brake chamber push rod to exceed its travel limit, bend the camshaft, or tear the diaphragm.

5. The only allowed "adjustment" operation
Reset instead of adjustment: Only reset tools (such as hex wrenches) are allowed to temporarily retract the adjuster push rod to the installation position (such as after replacing brake pads), and then the automatic mechanism takes over the compensation function again.
Operation key point: After resetting, the system needs to be triggered multiple times (such as stepping on the brake pedal) to automatically find the new reference point for the adjuster, and the slack must not be manually set.

Here's the quick-reference table