How do you manually adjust a slack adjuster?

Manually adjust the slack adjuster's ironclad rules

1. Prepare for Death

Reset the air pressure to zero

Turn off the engine and repeatedly apply the brakes 20+ times until the air pressure gauge needle touches the bottom and the exhaust valve hisses for 5 seconds. This is considered safe.

Wedge Locking

Place both wedges firmly behind the front wheels/in front of the rear wheels, engage reverse gear and pull the handbrake (for air brake models, the spring brake port must be blocked).

Catalogue Removal Prohibition

Heat the cast iron dust cover to 200℃ (dark red) with a propane flame, then gently pry it open with a flat chisel. Cold removal will inevitably break it.

2. Adjustment Operation (Feeler Gauge Method)

Insert the Grim Reaper's Ruler

Select a 1.0mm feeler gauge and insert it into the gap between the push rod and the adjusting arm. If it slides in easily, it's too loose; if it doesn't, it's too tight.

Worm Gear Killer Knob

Turning the worm gear counter-clockwise until the feeler gauge doesn't budge (brake shoes are firmly pressed against the brake drum)

Rewinding Killer Teeth

American Trucks: Rewind 3 full teeth (listen to the "click" sound to count)
European Trailers: Rewind 1/4 turn (90° precise turn)

Lock the Gates of Hell

Use a 36mm box wrench to lock the worm gear, then use a torque wrench to push it to 180Nm → Immediately apply a red paint mark.

3. Disaster Avoidance Rules

Excessive Tightening of the Death Sentence

Less than 1 tooth retraction → Brake drum temperature spikes to 482℃ within 5 minutes while driving → Tire rubber melts and catches fire

Loosening of the Soul-Binding Chain

Torque less than 150Nm → Vibration causes loosening → Pushrod travel exceeds limit → Diaphragm bursts with a gunshot sound

4. Autopsy-Level Road Test

5. Extreme Cold Purgatory Operation

-30℃ Iron Law:

Propane torch | Heat the locking nut until it emits blue smoke (removes ice crystals)
Feeler gauge Preheat the oil tank, insertion time ≤3 seconds (for cold welding prevention)

Wear step fatal pit

Drum inner wall step ≥2mm → smooth with angle grinder → readjust gap