What does that test involve?
I used to teach/babysit a CDL class. This is the airbrake test procedure that is performed during the CDL licensing exam/roadtest. Actions performed must be made verbal to the examiner hence the quotes.
CDL Brake Test:
Chock Wheels
Enter vehicle w/ 3 points of contact
Put on seatbelt
Safe start:
“I am going to perform a safe start. Press clutch, in neutral. Start engine, slowly release clutch.”
“Brake and ABS light went on and off. Oil pressure is rising”
Release Tractor and Trailer Brakes:
“I will release the trailer and tractor brakes by pushing in the tractor protection valve and the parking brake valve.”
Build Pressure/Purge:
“I am going to build pressure by stepping on the gas pedal and holding at 1000rpm. The governor cuts in at 100psi and cuts off at 120psi where it’s fully charged with a purge. (Purge) There is the purge. Primary at 119psi and secondary at 118psi indicating system is fully charged.”
Turn off engine:
“I will turn off the engine and turn key to ACC mode.
Air Leak test:
“I will perform the Air Leak test. I will begin the minute, listen for leaks and watch my gauge for any loss. I should not lose 4psi within the minute. Primary is at 119psi and secondary is at 118psi.” (Start minute)
(Minute ends) “Primary at 118psi and secondary at 117psi indicating 2psi loss which means it’s working properly and in operating range.
Applied Pressure Test:
“I will perform the Applied Pressure Test. I will fully apply the foot brake for 1 minute. After the initial loss I shouldn’t lose more than 4psi”
(Apply and hold foot brake) “After initial loss, the primary is at 110psi and secondary is at 112psi. I will begin the minute now.” (Start timer)
“The minute is up and the primary is 109psi and secondary is 110psi indicating system lost 3psi, is working properly and in operational range. That completes the Applied Pressure Test.” (Take foot off brake)
Low air warning light and buzzer test:
“Next test will be the Low Air Warning Light and Buzzer test. I will fan off air pressure by rapidly applying and releasing the foot brake. The low air warning light and buzzer should come on between 40-60psi. I will begin fanning now. Primary is at 109psi, secondary is at 110psi.” (Fan service brake)
“There is the Low Air Warning Light and Buzzer. The primary is at 56psi and secondary is at 55psi indicating they are working properly and in operational range. That completes the Low Air Warning and Buzzer Test.”
Turn off vehicle:
“At this time, I will turn the truck completely off.”
Tractor/Trailer Emergency Automatic Spring Brake Test:
“Next test will be the Tractor Trailer Spring Brake test. For this test I will continue fanning off brake pressure. Between 20-40 psi the tractor protection valve and parking brake valve should pop out. I will continue fanning. Primary is at 56psi, secondary is at 55psi” (Continue fanning brakes)
“The tractor protection and parking brake valve both popped out. The primary is at 39psi, secondary is at 38psi indicating that they are working properly and in operational range. That completes the tractor and trailer emergency automatic spring brake test.”
Grab Chocks:
“I will now exit the vehicle to grab the chocks.” (grab key, 3pt exit, grab chocks, 3pt entry.)
Put on belt and perform Safe Start: “I am going to perform a safe start.”
Build Pressure/Purge or Perform In-cab Pre-trip:
“Now I am going to help the air system build pressure by stepping on the gas pedal. The governor cuts in at 100psi and cuts off at 115psi which the system is fully charged with a purge. (Purge) There is the purge. The air supply pressure gauge primary and secondary needles are reading at 115psi indicating system is fully charged.”
Tug Test:
“Next test will be the tractor and trailer tug test. For this test I will push in the parking brake valve, put the gearshift in first gear and slowly releasing the clutch until I feel a tug.” (Pull Forward)
“There’s the tug indicating the trailer brake are working properly and in operational range. I will place the gearshift back in neutral.”
“Next I will pull out my parking brake and push in the tractor protection valve, putting the gearshift in first gear and slowly releasing the clutch until I feel a tug.”
“There’s the tug indicating the tractor brakes are working properly and is in operational range. I will place the gearshift in neutral. That completes the tug test.”
Service Brake Test:
“The final test is the Service Brake Test. I will release the tractor and trailer brakes, place the gearshift in first gear, accelerate to 5mph, and apply the brakes firmly. There shouldn’t be any delayed stopping, dipping to one side or unusual feel.”
(Accelerate up to 5mph, firmly apply brakes.)
“The vehicle didn’t pull to the side, no unusual feel or delayed stopping action indicating it works properly and in operational range. If it did, it could be low air pressure, suspension issue, or brake issues such as slack adjuster out of adjustment, worn brake pads or loose brake drums. That completes the Service Brake Test.”
