Air brakes utilize compressed air to reduce speed, typically in a larger vehicle like a truck or bus. The functionality of a vehicle's braking system can literally be a matter of life or death, and ensuring the proper functioning of air brakes sometimes requires their manual adjustment. Adjusting them is a precise but not a time-consuming process. It is ideally performed in a garage or other space where the vehicle's wheels can be suspended off the ground but can theoretically be done any place the vehicle can be stopped safely.
Instructions
- 1
Chock the wheels to prevent any movement during the procedure, maintaining each wheel's push rod at the same distance.
2Make sure the braking system is at full pressure. Then lower the emergency brake and push in the air valve to release the brakes.
3Mark where the push rod leaves the air chamber with a piece of chalk. Use the wrench or other suitable tool to remove the push rod from the brake chamber and calculate the distance from the chalk mark to the brake chamber. A gap of more than 3/4 of an inch indicates the need for adjustment.
4Find the manual slack adjuster, which is near the push rod, and begin turning. Make sure you're rotating it in the proper direction by determining whether the push rod removes air from the chamber as the brakes are applied. If it does, you're turning it the wrong way.
5Tighten the slack adjuster until you feel some resistance against the rotation. This tightness indicates the brake linings are snug against the drum. Rotate the adjuster back the other way a quarter to a half turn to loosen it slightly, assuring necessary distance between the linings and the drum.
