A locked-up brake chamber can be a serious issue for heavy trucks. Here’s a step-by-step guide to manually release a locked-up brake chamber safely and effectively.

Step-by-Step Guide

1. Identify the Locked Wheel or Axle

First, determine which wheel or axle has locked up. Once identified, slide under the vehicle and remove the dust plug from the spring brake chamber of the affected wheel or axle.

2. Remove the Release Bolt Assembly

Locate the release bolt assembly in the side pocket. Remove the release nut and washer from the release bolt, then slide the release bolt out of its holder.

3. Clean the Release Bolt

Thoroughly clean the threads along the length of the release bolt. This will make it easier to tighten the nut later on.

4. Insert the Release Bolt

Insert the release bolt through the opening at the rear of the spring chamber, where the dust plug was removed. Insert it into the pressure plate.

5. Secure the Release Bolt

Turn the release bolt a quarter turn clockwise in the pressure plate. This action secures the cross pin into the cross-pin area of the pressure plate, locking it into the manual release position.

6. Assemble the Release Bolt Washer and Nut

Reassemble the release bolt washer and nut on the release stud.

7. Cage the Compression Spring

Using a wrench, turn the release bolt assembly nut until the compression spring is 90-95 percent caged. This process requires significant effort as you are manually compressing a high-tension spring. Ensure that the push rod (adapter push rod or service push rod) is retracting while doing this. Avoid over-torquing the release bolt assembly (S-Cam Type 30/30 maximum: 68Nm/50ft-lb).

8. Exercise Caution

Once the brake is mechanically ‘caged,’ it will not function. Extreme care should be taken when moving a vehicle with the brakes in the ‘caged’ position to avoid accidents or further damage.

Conclusion

Manually releasing a locked-up brake chamber involves a precise and careful process. By following these steps, you can safely and effectively release the brake chamber, ensuring your vehicle remains operational until permanent repairs can be made. Always prioritize safety and exercise caution during this procedure.