The air brakes on International trucks are adjusted by the air brake slack adjusters. International trucks come equipped with different types of slack adjusters, but the air brake adjustment process remains the same. The slack adjusters operate by adjusting the brake shoes up and down inside of the brake drums. As the brake shoes wear down, the slack adjusters will also come out of adjustment and will need to be readjusted to keep the brake shoes at the proper distance from the inside surface of the brake drums.
Things You'll Need
- Wheel chocks
- 1/2-inch drive ratchet
- 1/2-inch drive socket set
Pull the International truck onto a level surface and apply the air brakes by pulling out on the air brake knob. Leave the engine running.
Get out of the truck and position the wheel chocks in the front and back of the rear wheels.
Release the air brakes by pushing the air brake knob back in.
Slide under the back of the International truck and locate the two slack adjusters on each side of the rear axle. The slack adjusters have an S-cam that extends out of the side of the slack adjuster to the back of the wheel hub.
Locate the adjustment bolt on the back side of the slack adjuster. Position a ratchet and a socket on the adjustment bolt. If the adjustment bolt is spring-loaded, push in on the head of the ratchet to unlock the adjustment bolt so that it can turn. Turn the adjustment bolt clockwise to compress the brake shoes to the inside surface of the brake drums. Once that the adjustment bolt stops turning, the brake shoes should be against the inside of the brake drums. Shine the flashlight through the back side of the wheel hub to ensure that the brake shoes are fully applied to the brake drum.
Turn the adjustment bolt counterclockwise between a 1/4 turn and a 1/2 turn to set the brake shoes the proper distance from the inside surface of the brake drums. Follow this same adjustment process for both slack adjusters.
Tips & Warnings
- If the slack adjuster makes a clicking noise when turning the adjustment bolt, this is normal.
- If the brakes are not properly adjusted, it can damage the brake drums by the brake shoes being too close to the drums, or the brakes will not work at all by being to far from the brake drums. This is the reason for the one-quarter to one-half turn slack adjuster adjustment bolt specification.
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