The Foundation Brake Analyzer (FBA) is an innovative S-Cam brake service tool. It allows the mechanic, or any other interested party who wants or needs to establish actual camshaft travel at each wheel end, or to identify the size of a brake drum present in most S-Cam foundation brake assemblies, without removing the brake drum. This tool eliminates the time consuming and costly removal of the brake drum to determine if the brake drum meets manufacturer’s specifications or is within legal standards.
How does it work?
The system is simple and easy to use. The gauge has three discs that are stacked one on top of the other, with the ever-present stainless steel pointer.
The largest disc is the stainless steel degree disc, designed to measure the total amount of S-cam travel evident in a specific S-cam foundation brake assembly. The second largest disc is the non-metallic brake lining disc. It is used to convert the brake lining thickness you measure in the specific brake assembly, into a number representing the number of degrees of S-Cam travel used up by the brake lining wear. The smallest disc is the non-metallic drum disc, which is utilized to determine the size of the brake drum.
The FBA photo above illustrates one actual brake test. The total amount of S-cam travel in this foundation brake assembly is 90 degrees. The brake lining thickness that remained measured 1⁄2 inch, which means that 60 degrees of S-Cam travel is used up by lining wear. Therefore, 90 degrees of total S-cam travel, minus 60 degrees of S-Cam travel as used up by the brake lining wear, the remainder is 30 degrees. The remaining 30 degrees of S-Cam travel is brake drum wear and initial brake lining to brake drum clearance.
This 30 degrees has a calibrated measurement beside it of .125. This means that this particular brake drum is worn 125 thousands of an inch. The FBA is equipped with a magnet that is used to secure the analyzer to the S-cam of the foundation brake assembly that is being tested. This design allows the gauge to be portable and can be moved from one assembly to another with ease.
The BLUE discs are used for standard brake lining with standard Q brake S-cams.
The RED discs are used for extended service brakes often referred to as “Q Plus” brakes and S-cams.
The GREEN discs are used when Extended life S-Cams are used with standard thickness brake lining. In other words Q Plus brake S-Cams on an axle, and the choice is made to install standard 4515 lining rather than the more expensive 4707 lining.