BC Transit – Air Brake Course

Apply the principal from the previous slide to the example below:
C
A
D
B
“A” represents the slack adjuster in
the foundation brakes. As pressure is
applied, the slack adjuster works as a
lever, on shaft “D.” As the “S”cam
attached to the shaft rotates, a
mechanical advantage is achieved at
points “B” and “C”. If the slack
adjuster were 6 inches in length, and
the “S” cams were 1 inch in length,
the ratio would be 6:1.
21