TheoryCDL Doubles Triples Practice Test Video
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Q1You are about to couple a second trailer to a loaded converter dolly. The dolly's pintle hook closes but you notice the latch does not fully seat. What is the correct action?
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✓ Correct answer: Do not couple the trailer; the pintle hook latch must be fully closed and locked before any movement
The CDL manual states that all coupling devices must be fully engaged and locked before moving; a pintle hook that does not fully latch is a defect that prohibits operation regardless of safety chain status.
Q2Before coupling a converter dolly to the rear of a first trailer, the dolly landing gear should be:
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✓ Correct answer: Adjusted so the dolly fifth wheel is slightly lower than the trailer's rear kingpin height
The CDL manual specifies that the converter dolly's fifth wheel should be positioned slightly below the kingpin height of the trailer being coupled so the trailer rides up onto the fifth wheel as it is pulled into position, ensuring full engagement.
Q3A driver is assembling a triple-trailer combination. After coupling the second trailer, when should the third trailer's brakes be released for the first time during assembly?
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✓ Correct answer: Only after all air lines are connected, the trailer glad hands are charged, and the combination has been test-pulled forward to check coupling
Per the CDL manual coupling procedure, air lines must be connected and the system charged before brakes are released; and coupling should be verified with a test pull before the trailer's parking brakes are released for road movement.
Q4A driver is performing a coupling inspection and finds that the converter dolly's fifth wheel locking jaws have closed around the kingpin but a gap exists between the fifth wheel plate and the trailer apron plate. What does this indicate?
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✓ Correct answer: The kingpin may not be fully seated; the trailer may be resting on the fifth wheel lip rather than the plate surface
The CDL manual states there should be no gap between the upper fifth wheel plate and the trailer apron plate after coupling; a visible gap means the kingpin has not dropped fully into the jaws and the coupling is incomplete.
Q5After coupling the converter dolly to the rear of the first trailer using a pintle hook, what immediate check must the driver perform before backing under the second trailer?
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✓ Correct answer: Verify that the pintle hook is locked and the safety chains are connected
The CDL manual requires the driver to verify that the pintle hook latch is secured and locked and that safety chains are properly connected before any movement toward the next trailer in the combination.
Q6When building a doubles combination on a grade (slope), what additional step must be taken before uncoupling the tractor from the first trailer?
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✓ Correct answer: Chock all trailer wheels to prevent rolling before the tractor brakes are released
The CDL manual specifies that wheel chocks must be used on any grade before uncoupling because trailer parking brakes alone may not reliably hold a loaded trailer on a slope.
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