Universal (BWI) Brake Wear Indicator
US Patent #5,535,854 July 16, 1996
This invention relates to a one piece brake lining wear indicator that is a reversible circular dial. Calibration marks are included on both sides of the circular dial along with several accentua-ting notches on the outside circumference of the dial. When the dial is coupled to the splined end of a rotatable brake camshaft that is equipped with manual or automatic slack adjusting levers, the dial acts as an indicator of the amount of brake lining wear that occurs inside the brake drum.
Brake Wear Indicator meters are manufactured from 5052H32 marine (salt) corrosion material and anodized to US-MIL-8625-E to provide best possible wear factors.
When should you install the BWI Indicators?
A very convenient time is during a brake reline. The brake shoe rollers must be returned to ZERO degrees of rotation as show in Pic 2.
With park brake released, and the rollers at ZERO a line from the center of the clevis pin to the center of the S-cam Shows where the S-Cam must be marked with a cold chisel, as shown in Pic 3.
How will you know when brake life is done?
S-Cam is rotated by the slack adjuster. When S-Cam rotation reaches 120 degrees with the brake shoes against the brake drums, the brake is in an Out-Of-Service condition, as shown here. The meter begins life with the "F" pointer meaning FULL Pointed at the clevis pin. To check brake wear with the parking brakes released, rotate the meter to line the "F" pointer up with the ZERO timing mark created on the S-Cam. Count backwards to an imaginary line between the clevis pin and the center of the S-Cam. Increments on the meter equal 3 degrees. Add 5 degrees to the reading you have to avoid have to move the shoes against the brake drum.
Always record your findings in the vehicle file.
There are three (3) Universal Brake Wear Indicator meters.
CA92-GPCT 1 1/4" ,
CA92-DPCT 1 1/2"
CA92-BPCT 1 5/8 ",
To locate the meter you want, measure the inside
diameter of the outside spacer washer on the S-Cam you wish to replace, Use one of the meters above.
For Technical information on BWI order
Brak Chek's BWI Tech manual.
Toothed (BWI) Brake Wear Indicator
US Patent # 5.535,854 10 Spline
Flat Meters To install toothed meters, remove locking ring and outside spacer washer. Install the meter and re-install the lock ring.
"F" pointer indicates FULL and is aimed at the clevis with the rollers at ZERO.
3 = 0/. full, 2 = 1/2 full, 1 = 1/4 full, E = EMPTY @ 120 degrees
1 1/4" x 10 spline Flat meter for Steering axle CA92-FPCT
1 W x 10 spline Flat meter for Dive or trailer
1 1/2" x 10 spline Flat meter Chrome CA92-APCT-C
10 Spline Cup Style Meters
1 1/2" x 10 spline meter Zero TDC CA92-BPCT-G Gold
1 1/2" x 10 spline meter 9 degrees right CA92-BPCT-B Blue
1 W x 10 spline meter 9 degrees left CA92-BPCT-S Silver
Each inner and outer tooth is 18 degrees. 20 x 18 = 360 degree All 10 spline camshafts are held by the barrel during manufacture, thus there is no relationship between the S-Cam head and the spline.
How are 10 spline meters identified? Pic 3
By the location of the "F" pointer and if flat or cup style is
needed. The cup shown in Pic 2 is a TDC model.
It is also available in 9 degrees left or 9 degrees right.
The location of the "F" pointer shown in Pic 2 is a TDC. However, there are Blue and Silver finished meters that have the "F" pointer lined up with the edges of the spline tooth. This was necessary because the 10 tooth s-cam spline meter is not easily lined-up with the clevis pin in the slack adjuster.
28 Spline Cup Style Meter
For use on S-Cams where fleet manager wants a positive lock indicator rather than floating universal style. In the 28 spline cup, each tooth is roughly 6.4285 degrees.
All 28 spline s-cams are undercut, thus the need for a cup style meter.
For Technical information on BWI meters order Brak Chek Ltd.'s BWI Tech Manual.