Air Brake Leak Down Test

R and M Diesel
Short drive from down town Little Rock, Arkansas
Close to I-30 and I-530.

The Federal Motor Carrier Safety Administration of the U.S. Department of Transportation requires operators of commercial motor vehicles to perform a pre-trip inspection to verify the integrity of all components and equipment.
This inspection helps maintain safe operation.
States have different approaches to the air brake test.

Air Brake Pre-trip Inspection:

1. Start engine and build pressure to 90-110 lbs
2. To test parking brake with engine running:
    A. Apply Parking Brakes
    B. Put in gear, then slowly release clutch
    C. Vehicle must stay stopped where it is
3. Shut engine down, turn key back on.
4. Charge air system (Push one knob in)
5. Wait for initial fill.
6. Wait one minute for air leakage, rate should be no more then 2 psi.
7. Apply 90 lbs pressure to brakes and hold for one minute.
    Air leakage should be no more then 3 psi. 8. Pump Brakes till red light/buzzer comes on ( about 60 lbs) 9. Keep pumping brakes till one knob pops out.
    (about 20-40 psi) Brakes will set.

At Road Inspection Station.

Governor Cut In and Cut Out
 With engine running release brakes (push both buttons in) Build Air to 120 psi and Fan down to 100 psi
 Bring RPM up to just under 1500 and say that cut in works when needle starts to rise.
 Keep RPM at 1500 and tell officer that it should cut out at about 120 psi.
 Continue to let needle rise and when needle stops tell officer needle has stopped at 120 psi.
 Cut out works.
 Apply the Brakes (pull out both buttons) and shut off engine.
 Put key in the ON position.

Air loss rates (3 psi & 4 psi)
 Release Brakes (push both buttons in) and after initial loss of 5 – 15 psi the system cannot lose more than 3 psi in one minute.
 Time it and after one minute tell officer it did not.
 Now apply firm pressure to the service brake and after another initial loss of 5 ? 15 psi the system cannot lose more than 4 psi in one minute.
 Time it and after one minute say it did not.

Low Air Warning Alarm (60 psi) 
 With key in the ON position fan the brake pedal so air drops.
 Tell officer that the alarm must come on BEFORE the system drops below 60 psi.
 Tell officer that it did when alarm comes on.

Spring Brakes (Between 20 & 40 psi)
 Continue fanning brake pedal dropping air pressure.
 Check that spring brakes come on between 40 and 20 psi.
 Both buttons will pop out.
 Brakes are applied.
 Tell officer that they did.

Rate of Build Up (85 ? 100psi /45sec.)
Start engine and bring RPM to just under 1500 to build up air.
1st Make sure alarm stops after system builds past 60 psi.
Tell officer that alarm has stopped and you will time it from 85 to 100 psi.
Tell him that it must take 45 seconds or less.
When it reaches 85 psi say 85 and timing.
Time rise in pressure from 85 to 100 psi.
Tell officer how long it took.
Continue to let air build to 120 psi.
Put In Gear.
Shut Off Engine.

Take out Keys. Get Out and Close Door. Get Chocks.

 Test Brakes (Parking and Service)
 Only brake on is one you are testing!
 Push tractor brake in.
 Check trailer brakes & fifth wheel connection.
 Pull tractor brake out.
 Push trailer brake in and check Tractor Parking Brake.
 Take out of gear and build to 120 psi.
 Shift into 2nd gear and drive forward
 Pull down trolley to check trailer brakes.
 Push trolley back up to release and while in 2nd gear drive forward at 5 mph.
 Use service brake to stop truck.

Inform officer.
No Unusual Feel to Pedal
No Delayed Stopping Truck
Did Not Pull to Left or Right
No Shudder in Wheel No Unusual Sounds or Smell

Mobile Service for Farms and Roadside for Central and Southern Arkansas .

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2100 Highway 46 North
Sheridan, Arkansas 72150
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Call Rusty – 870-941-6160