Doubles and Triples Flashcards

What is the correct position of the converter dolly air drain valve during the pre-trip inspection?

Answer: Fully closed

During the pre-trip inspection, the converter dolly air drain valve should be fully closed. This valve is primarily used to drain moisture or contaminants from the air tank. Keeping it closed during operation is essential to maintain proper air pressure within the braking system, as an open valve would cause a continuous air leak and lead to a loss of brake pressure.

Which of the following driving practice is recommended for doubles/triples?

Answer: Allow more following distance

Doubles and triples are significantly longer and heavier than single trailers, requiring much greater stopping distances. Allowing more following distance provides the driver with additional time and space to react to hazards and brake safely. This practice helps compensate for the increased momentum and potential for jackknifing or rollovers associated with multi-trailer combinations.

What is the correct amount of space between the upper and lower parts of the fifth wheel on the dolly when coupled to a trailer?

Answer: No space

When a converter dolly is properly coupled to a trailer, there should be no space between the upper and lower fifth wheel components. A tight connection ensures that the trailer is securely attached and prevents excessive movement or play, which could lead to instability or separation. Any gap indicates an improper or unsafe connection that needs to be corrected for safety.

What should be inspected on the landing gear for doubles/triples?

Answer: All the above

During a pre-trip inspection of doubles/triples, all aspects of the landing gear must be thoroughly checked. This includes ensuring they are fully raised with no missing parts, that the crank handle is properly secured, and that there are no air or hydraulic leaks if power-operated. These comprehensive checks confirm the landing gear is in a safe, operational condition and won't interfere with driving or detach during transit.

Where will you find shut off valves on doubles and triples?

Answer: [*]Both service and emergency air lines

Shut-off valves are found on both the service and emergency air lines of doubles and triples. These valves are critical for controlling the flow of air to the brake systems of each trailer. They must be correctly positioned (open for intermediate connections, closed for the last trailer) to ensure proper air pressure and braking function throughout the entire vehicle combination.

If your tractor protection valve malfunctions, what could happen?

Answer: All of the above

The tractor protection valve is a vital safety device that prevents a complete loss of air pressure in the tractor's brake system if there's a leak or separation in the trailer's air lines. If it malfunctions, a leak in the trailer's air hose could rapidly drain air from the entire system, potentially causing the trailer's emergency brakes to activate prematurely or draining the tractor's air supply, leading to a loss of braking capability.

What is the proper procedure to test the trailer service brakes?

Answer: Use trolley valve to apply brakes and check to see if you feel the trailer brakes come on

To properly test the trailer service brakes, you should use the trolley valve (hand valve) to apply only the trailer brakes. This allows you to isolate and feel the resistance or drag from the trailer brakes as you move forward slowly. This method confirms that the trailer's service brakes are engaging effectively and independently of the tractor's brakes.

Which trailer of a triple trailer is most likely to roll over?

Answer: The rear trailer

In a triple trailer combination, the rear trailer is most susceptible to rollovers, especially during turns or sudden maneuvers. This is due to the 'crack-the-whip' effect, where forces amplify down the train, causing the last trailer to swing out wider and experience greater lateral forces. Its position at the end of a long lever arm makes it inherently less stable.

What is the correct trailer height when you connect the converter dolly to the rear trailer?

Answer: Trailer is slightly lower than the center of the fifth wheel

When connecting a converter dolly to the rear trailer, the trailer's fifth wheel should be slightly lower than the center of the dolly's fifth wheel. This ensures that as the tractor backs up, the dolly's fifth wheel ramps up and under the trailer, allowing for a secure and positive lock. If the trailer is too high, it might not couple correctly, and if too low, it could damage the fifth wheel or trailer.

Which of the following procedures should you do when connecting the converter dolly to the rear trailer?

Answer: 1st and 3rd options

When connecting a converter dolly to the rear trailer, it's crucial to ensure the trailer brakes are locked to prevent the trailer from rolling during the coupling process. Additionally, the trailer must be positioned slightly lower than the center of the fifth wheel on the dolly. This allows the fifth wheel to properly slide under the trailer and securely lock into place, ensuring a safe connection.