CDL Air Brake Test Guide

Cards · 52

Engine oil pressure rise time limit upon start

Within 3 to 5 seconds (otherwise shut down engine immediately)

Initial verbal gauge selection statement

I will be using my primary gauge for all of my tests and begin my tests with maximum air pressure.

Pre-check action if initial air pressure is above 100 psi

Pump brake pedal down to 90 psi or below before starting to ensure governor cut-in

Air compressor governor cut-out pressure range

Between 120 and 140 psi

Verbal declaration when governor cuts out normally

My needle has stopped rising.

Verbal declaration if governor cuts out below 120 psi or above 140 psi

My governor cut out outside normal range.

Applied Brakes Test: Step 1 (Transmission)

Put transmission in 1st gear

Applied Brakes Test: Step 2 (Engine)

Turn the engine off

Applied Brakes Test: Step 3 (Clutch)

Release / unclutch the clutch pedal

Applied Brakes Test: Step 4 (Ignition)

Turn ignition key back to ON position to cycle gauges (do NOT restart engine)

Applied Brakes Test: Step 5 (Valves)

Push both yellow (parking) and red (trailer supply) valves in

Applied Brakes Test: Step 6 (Timer preparation)

Set / prepare timer for 1 minute

Applied Brakes Test: Step 7 (Pre-application needle)

Wait for air pressure needle to stabilize

Applied Brakes Test: Steps 8 & 9 verbal statement

Can't lose more than 4 psi for this tractor/trailer combination.

Maximum allowable air loss for combination vehicle (1-minute applied test)

No more than 4 psi

Applied Brakes Test: Step 10 (Pedal action)

Apply firm, steady pressure on the service brake pedal

Applied Brakes Test: Step 11 (Applied needle)

Wait on the needle to stabilize under pressure

Applied Brakes Test: Step 12 verbal start declaration

Needle stabilized, gauge reads [?] psi, my minute starts now.

Applied Brakes Test: Step 13 action immediately after verbal start

Start the 1-minute timer immediately

Applied Brakes Test: Step 14 & 15 action during the timed minute

Maintain firm, steady pressure on the brake pedal throughout the entire minute

Applied Brakes Test: Step 16 verbal declaration (no air loss)

Minute has ended, primary gauge reads [?] psi, I have had no air loss.

Applied Brakes Test: Step 17 requirement if air loss occurred

Report the exact amount of air lost to the examiner (e.g., I lost 2 psi)

Applied Brakes Test: Step 18 final action

Release foot from the brake pedal

Low Air Warning Test: Opening verbal declaration

The next test I will perform is the Low Air Warning Test. A low air warning light and/or buzzer must come on no lower than 55 psi.

Low Air Warning Test: Driver action

Pump the service brake pedal steadily to bleed off air pressure

Low Air Warning activation threshold

No lower than 55 psi

Spring Brake Pop-Out Test: Driver action

Continue pumping the service brake pedal steadily to bleed off remaining air

Spring Brake Pop-Out activation range

Between 20 and 45 psi

Spring Brake Pop-Out Test: Required verbal statement

My valve(s) popped out at [?] psi.

Procedure if only one valve pops out initially during Spring Brake Test

State its pressure, then continue pumping until the second valve pops out

Declaration made upon finishing the entire air brake inspection sequence

This concludes my Air Brakes Systems Test.

Protocol after first failure of an air brake test

Notify examiner, perform safe start, rebuild pressure to 120-140 psi, and re-test

Protocol after second failure of an air brake test

Notify examiner you will place the truck out of service and notify your instructor

Definition: Governor Cut-Out

The mechanism that stops the compressor from pumping air once maximum operating pressure is reached

Definition: Applied Brakes Test

A timed 1-minute test measuring system air leakage under full service brake application

Definition: Low Air Warning

A visual and audible signal activating at or above 55 psi alerting the driver of low pressure

Definition: Spring Brake Pop-Out Valves

Emergency valves designed to pop out automatically between 20 and 45 psi to engage parking brakes

Definition & procedure: Safe Start

Depress clutch, verify neutral, turn key on, wait for gauge sweep, then start engine

Target engine RPM when revving to assist air pressure build-up

1100 RPM

Color identification: Parking brake control knob

Yellow (diamond shape)

Color identification: Trailer air supply valve

Red (octagonal shape)

Primary gauge selection rule during CDL in-cab air brake test

Use the primary air pressure gauge for all in-cab test readings

Fill in the blank: Oil pressure must rise within ___ to ___ seconds.

3; 5

Fill in the blank: Governor cut-out must occur between ___ and ___ psi.

120; 140

Fill in the blank: Maximum combo air loss during 1-min applied test is ___ psi.

4

Fill in the blank: Low air warning must activate no lower than ___ psi.

55

Fill in the blank: Valves must pop out between ___ and ___ psi.

20; 45

Fill in the blank: Step 1 is to place transmission in ___.

1st gear

Fill in the blank: Step 4 key position is to ___ gauges without starting.

Cycle

Fill in the blank: Step 5 is to push yellow and red valves ___.

IN

Fill in the blank: Verbal conclusion: '...reads [?] psi, I have had ___.'

no air loss

Fill in the blank: Final declaration: 'This concludes my ___ Test.'

Air Brakes Systems