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Practical Examination for Air Brake Endorsement

Items needed:
  • Awareness of size and type of brake chambers on the vehicle
  • Means of holding the brake pedal in the applied position
  • Means of marking pushrod if using method 1
  • Checklist of the test procedures
  • Wheel chocks or blocs
  • Watch with second hand or stopwatch
  • Device to measure the pushrod stroke
  • Chart of brake adjustment limits

  • Protective headgear (hard hat)
  • Protective eyewear
  • Protective footwear


    • PART 1: Operating Components / Functional Tests

    1. Secure the Vehicule:
    ...1) Apply SpringBrakes and
    ...2) Wheel Blocks
    2. Low Air Pressure Warning Device
    ...1) Turn engine ON
    ...2) Make sure the pressure in normal operating range (over 90)
    ...3) Pump brake until Warning
    ..... Good if 55 psi or more
    3. Test Air Pressure Build Up Time
    ...1) RPM between 600 - 900
    ...2) Note time it takes from 85 to 100 psi.
    ..... Good if 2 min or less
    4. Confirm Air Compressor Governor Settings
    ...1) Build up air pressure to Max. Note the Cut Out Pressure.
    ..... Good if between 100 and 135
    ...2) Pump down air pressure 20 to 25 psi, let everything go and check if air pressure needles start going up
    ..... If not, pump down another 5 psi, and continue the same procedure until Cut In.
    ..... Good if 80 psi or higher
    5. Test Air Loss Rate
    ... 1) Release both brakes
    ... 2) Make sure air pressure is over 100 psi
    ... 3) Press and hold brake pedal down for 1 min while Engine is OFF
    ..... Max 3 psi for 1 equipment
    ..... Max 4 psi for 2 equipments
    ..... Max 6 psi for 3 or more equipments
    6. Test Automatic Application of Trailer Brakes
    ..... Apply Trailer Brakes and hear the Air exhausting from Chambers
    7. Test the Tractor (Towing) Vehicle Protection Valve
    ..... Remove blue service line, press and hold brake pedal and check if any air is exhausting from blue service line
    8. Test Spring Brakes
    ..... Try moving the vehicle while brakes applied (First Trailer, then Tractor)
    9. Drain Air Tanks
    ..... Start with Supply Tank (The One with no Gauge)
    ..... Finding the Supply Tank: Turn OFF the engine, then drain tanks (one by one) and check if needle moves down)

    PART 2: Brake Adjustment

    10. Inspecting Brake Adjustment
    ... 1) Make sure pressure is 90 - 100, then turn engine OFF
    ... 2) Release Spring Brakes
    ... 3) Mark Pushrod, Apply Fully the Service Brakes and measure the PushRod Stroke Out
    ..... Good if Equal or less than the Adjustment Limit of the Brake Chamber.
    11. Indicate Defective Vehicle Condition
    ..... Written report to the operator and avoid using the vehicle

    Brake Adjustment Limits - Clamp Type Brake Chambers

    Max pushrod stroke with 90 - 100 psi (621 - 690 kPa) and full brake application

    Size Marking Outside Diameter Adjustment Limit
    6 none 115 mm (4 1/2") 32 mm (1 1/4")
    9 none 133 mm (5 1/4") 35 mm (1 3/8")
    12 none 144 mm (5 11/16") 35 mm (1 3/8")
    16 none 162 mm (6 3/8") 45 mm (1 3/4")
    16L L Stamped In Cover, Stroke Tag 162 mm (6 3/8") 51 mm (2")
    20 none 172 mm (6 25/32") 45 mm (1 3/4")
    20L L Stamped In Cover, Stroke Tag 172 mm (6 25/32") 51 mm (2")
    24 none 183 mm (7 7/32") 45 mm (1 3/4")
    24L L Stamped In Cover, Stroke Tag 183 mm (7 7/32") 51 mm (2")
    24LS Square Ports, Tag & Cover Marking 183 mm (7 7/32") 64 mm (2 1/2")
    30 none 205 mm (8 3/32") 51 mm (2")
    DD3 none 206 mm (8 1/8") 57 mm (2 1/4")
    30LS Square Ports, Tag & Cover Marking 205 mm (8 3/32") 64 mm (2 1/2")
    36 none 228 mm (9") 57 mm (2 1/4")

    Any question or comments: E-mail me

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