Do you know how many brakes can be out of adjustment before you're placed out of service?
The formulae for figuring out how many brakes it takes to place you out of service is easy to figure out. The North American standard out of service manuel says that you can't have more that 20% of your brakes out of adjustment. Here's a typical example of how to figure out you're 20%:
A 5 axle truck has 10 brakes. 20% of 10 is 2 brakes, or .2 x 10=2. 2 brakes out of adjustment on a five axle vehicle places it out of service.
While making these calculations you end up with a fraction on the number of defective brakes (4.8, 2.3 etc) they must all be rounded UP (4.8=5, 2.3=3).
Checking individual defective brakes
First, the vehicle's air pressure is brought between 90-100psi and fully apply the brakes. One brake that is at 1/4" beyond its adjustment would be one defective brake. An example would be a clamp type 30 brake (max pushrod travel is 2" for this brake type) that has a pushrod travel of 2 1/4" inches.
If you apply the brakes and you have two brakes that are less than 1/4" (1/8") those two brakes out of adjustment would equal 1 brake. In addition if you had a single brake that was less than 1/4" out of adjustment, that would be considered a half of brake out of adjustment.
