OOSC, Part II, Item 1. Brake Systems, a. Defective Brakes - Updates to the Brake Adjustment Reference Charts

In order to address reports that inspectors are encountering brake chamber types/sizes which are not in the current brake chamber tables, the Chair of the Vehicle Committee has asked for a review of the tables by industry. This Request for Action is in response to the results of that review. Based on discussions with brake chamber suppliers and the SAE Brake Actuator Subcommittee it was determined that that a long stroke clamp type 20 chamber with a 3 inch maximum stroke is the only chamber that needs to be added. While there are other types of chambers that are being used on air disc brakes that do not appear in the tables, these chambers have totally enclosed pushrods that cannot be measured and therefore they need not be added.

The type 20 long stroke clamp type chamber with a 3 inch maximum stroke and exposed pushrod is being encountered in the field on s-cam air brakes and its brake adjustment limit data is needed by inspectors in order for them to accurately assess adjustment level.

Add the type 20 long stroke clamp type chamber with a 3 inch maximum stroke to the OOSC tables. The outside diameter is the same as that for the other type 20 clamp ring chambers (6-25/32 inches or 172mm) and the brake adjustment limit is 2-1/2 inches (64mm).