How can you test that air flows to all trailers?
Answer: Use the tractor parking brake and/or chock the wheels to hold the vehicle. Wait for air pressure to reach normal, then push in the red "trailer air supply" knob. This will supply air to the emergency (supply) lines. Use the trailer handbrake to provide air to the service line. Go to the rear of the rig. Open the emergency line shut-off valve at the rear of the last trailer. You should hear air escaping, showing the entire system is charged. Close the emergency line valve. Open the service line valve to check that service pressure goes through all the trailers (this test assumes that the trailer handbrake or the service brake pedal is on), and then close the valve. If you do NOT hear air escaping from both lines, check that the shut-off valves on the trailer(s) and dolly(ies) are in the OPEN position. You MUST have air all the way to the back for all the brakes to work.
Learn More :
- Compared with a straight truck or bus, there are ___ things to inspect in combination vehicles
- The service line
- You should not back a tractor under a trailer until the whole air system is
- You are coupling a tractor to a semi-trailer. You have connected the air lines. Before backing under the trailer, you should
- For coupling to be completed, the safety catch for the fifth wheel locking lever must be
- The trailer hand valve works the trailer brakes. Which of these statements is true?
- You should not use the trailer hand valve while driving because
- What is the emergency air line?
- After the trailer has been coupled to the tractor, the tractor protection control valve should be placed in what position?
- You supply air to the trailer tanks by
- Glad hands are used to connect the
- Under good driving conditions, you should leave at least one second of space between your vehicle and the vehicle ahead for every ___ feet of your vehicle's length
- After you supply air to the trailer, make sure the air lines are not crossed and the trailer brakes are working. This is done by
- You are driving a combination vehicle when the trailer breaks away, pulling apart both air lines. You would expect the trailer brakes to come on and
- A trailer is most likely to jackknife when it is
- The front trailer supports are up, and the trailer is resting on the tractor. Make sure that
- Air lines on a combination vehicle are often colored to keep them from getting mixed up. The emergency line is ___; the service line is ___.
- While you are driving, your emergency air line breaks or gets pulled apart. The loss of pressure will cause the
- Describe what the trailer air supply controls does
- If the brakes did not release when you pushed the trailer air supply valve, you should
- You have a major leak in the service line, and you apply the brakes. Service air pressure will escape and cause the
- After connecting the air lines but before backing under the trailer, you should
- What is the emergency air line for?
- Which of the following is true about off-tracking or "cheating?"
- In general, the higher your truck's center of gravity, the
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