A set of visual brake stroke indicators costs no more than a few bucks per wheel-end, and can save hundreds by preventing just one out-of-service situation. So why aren't more fleets and owner-operators using them?
Recollections abound of lying under a trailer with a 9/16ths wrench and a hammer adjusting my brakes. I went through the procedure each time I picked up a different wagon, and I set up my tractor brakes at least once a week in the days before automatic brake adjusters. Today it seems we've come to think of automatic brake adjusters and infallible brake adjusters, and nothing could be further from the truth.
I mean no disrespect to the producers of automatic brake adjusters -- they have dramatically improved brake performance and reduced the out-of-service rate due to bad brake adjustment by nearly half -- but since the OOS rate for brake adjustment still hovers around the 20-22 percent range, clearly something still needs to be addressed.
Automatic brake adjusters, or autoslacks as they are often called, are designed to maintain a pretty close line between under and over-stroking. If a brake has a 2-in. stroke limit, an autoslack will probably maintain a stroke length of about 1-5/8 to 1-3/4 of an inch. There's not a lot of margin there.
And chances are, when a wheel equipped with an automatic adjuster is over-stroking it's not the fault of the adjuster, but of something else at the wheel-end, such as worn cam bushings, a seized clevis pin or something. The warranty rate on autoslacks is very low, I'm told, which buttresses my previous statement. Over-stroking with autoslacks is very often an indicator of some other problem with the foundation brake.
Amazingly, overstroking autoslacks are often readjusted and set to the proper length -- even by so-called qualified mechanics. Autoslacks should never be "adjusted" to cure excess pushrod travel. If there's any misunderstandings about adjusting automatic brake adjusters, please read the NTSB report on the truck crash at Glenn Rock, Penn. that claimed one life in 2003. NTSB attributed that incident to slack adjusters that were so badly worn due to constant readjustment that were unable to maintain their stroke, and just backed off each time the brakes were applied.
That's another story for another day. Getting back to brake stroke indicators, we have a situation where problems can occur with a mission critical component and there's no practical roadside fix, short of inspection the brake to reveal the source of the over-stroke condition.
Given the CSA emphasis on brake stroke -- violations carry four points -- and the semi-annual reminders we get from CVSA on our brake adjustment shortcomings, why is more emphasis not placed on checking brake stroke?
Let's face it; drivers are not going to do a mark-and-measure brake inspection every day. If they tell you they are or if you think they are, you're deluding yourself. It just doesn't happen.
So what's the answer to a 22-percent out of service rate due to improper brake adjustment? Visual brake stroke indicators. When installed properly, and when drivers check them periodically, they are near-guaranteed prevention of brakes out of adjustment citations.
I've noticed over the years that almost every Canadian truck or trailer you see has visual brake stroke indicators installed, but a very small percentage of American trucks have them. No commentary here, just an observation, but I've always wondered why something so inexpensive and so reliable that can prevent such a costly problem isn't on every wheel on every truck in the land.
