Brake Wear Indicator
Prevent premature auto brake adjuster damage
Frequent back-off shortens the life of automatic brake adjusters.
Reduce S-Cam brake inspection time.
Monitor brake wear between wheel pulls.
BWI (Brake Wear Indicator) meters could be called brake cam rotation meters.
Top left shows brake wear indicator “F”, aimed at yoke pin with brake shoe rollers backed off to Zero during a brake reline.
Top right shows brake wear indicator “F”) at 30 degrees of accumulated S-Cam rotation.
Bottom left, shows brake wear indicator “F” at 90 degrees of accumulated S-Cam rotation
The easy part about this position is that the condition can be identified without having to remove dust-shields or brake drums.
Brake wear indicators are available in the same sizes as the outer spacer washer they replace.
There is a distinct difference between
A “Q-Plus” S-Cam will measure 1-1/8” (inch). A “Q-Plus” S-Cam is used with the thicker, “Q-Plus” brake lining.
If “Q” shoes are installed in place of “Q-Plus” shoes, the brake wear indicators will indicate a starting position much higher up the S-head ramp after the brakes are properly adjusted.
Whatever shoe and camshaft combination is used to service your S-Cam brakes, cam rotation BEGINS at Zero and ENDS at 120 degrees.
Uneven Brake Wear
If a brake meter on one wheel indicates more accumulated rotation than the others, this could mean one brake is doing more than its share of the braking. Identify why? Don't wait for a wheel fire or other tragic event?
BWI meter technology allows the monitoring of accumulated brake adjustments made by the automatic slack adjuster at each brake.
Each installed meter converts accumulated brake adjustments into degrees of brake camshaft rotation. Visual lining wear inspection is done by a simple glance from a trained brake mechanic. The meter monitors total accumulated brake wear. When the notch on the meter has rotated 120° and the “E” (meaning empty) is facing toward the yoke pin on the adjuster, brake work is required. It may be brake lining, or drum, but 120 degrees means this brake is out of service.
Meters”. With the increased focus on brake safety at roadside inspections, brake mechanics need all the training, understanding, and knowledge of tools available to them.
Mechanic must INDEX the S-Cam at Zero degrees of rotation and replace the spacer washer with a meter.