Professional drivers do a brake check before starting the day AND before fully committing to a downgrade.
This can mean daily doing those ‘dumb’ checks required by the CDL test like the Air Brake Leak Down Test and the Stall Test, and fully stroking the brakes by pressing the pedal to the floor—so the automatic slack adjusters (ASAs) stay in adjustment.
Air-Brake Check Checklist
Chock or Block wheels and start the engine
Build air pressure up to 120 PSI
Turn engine off
Release the parking/trailer brakes (push knob(s) in/down) After air pressure stabilizes wait 1 minute
Air Pressure should drop no more than 3 PSI in a minute Hold the brake pedal down firmly
After pressure stabilizes hold pedal for 1 minute
Listen for audible air leaks
Air pressure should drop no more than 3 PSI in one minute (tractor only) or 4 PSI in 1 minute if combination unit
Turn the ignition switch on (but not the engine)
Pump the brake pedal until the low air warning buzzer sounds at 60 PSI
Continue to pump brake pedal until the red brake button pops out between 20 & 45 PSI
If a trailer is attached:
With trailer brakes applied and tractor brakes released, complete 2 firm tug tests to be sure the trailer brakes are properly adjusted and hold against the tug
When the truck is in motion apply the service brakes to be sure they are operational
Check the Brakes before a Downgrade, Too . . .
The integrity of the brake system needs to be checked before a downgrade as well. It only takes a second to see if you have some pedal. And be sure to place the vehicle in the proper gear for the grade.
Why Are Daily Brake Checks Necessary?
Daily brake checks are necessary for several reasons:
- All equipment degrades over time due to wear and tear. Drivers then start to adjust their driving behavior to compensate for the failing performance of the brake system. There have been serious crashes where it was later found that only one of the foundation brakes were properly working and in adjustment.
- We need to catch things before bigger problems occur
- Sometimes adjustments are made that compromise the system (slacks are backed off by mistake, or air lines mis-routed during a service—It happens!)
- Your life and the lives of the public are on the line
- Brake citations—year after year—are the number one citation during roadside inspections
Stay in Control
A cardinal rule of diving is always keep the vehicle under control—no matter the situation. It is never a good situation when a driver loses control of the vehicle.
Daily brake checks can catch a small problem before it turns into a big problem, help keep the ASAs in proper adjustment, and help the driver to always stay in control.
Thank you for reading this.
Learn more about brake inspections: Commercial Motor Vehicle (CMV) Inspections