Coupling & UncouplingQuestion 15 of 60
Why is it important that the kingpin be properly locked, not just resting on the closed fifth wheel jaws?
a.To reduce fuel use
b.To keep the fifth wheel greased
c.Because a kingpin resting on top of the closed jaws (a false coupling) can slip out and separate the trailer
d.Because it makes turning easier
Explanation
A false coupling occurs when the fifth wheel jaws close but the kingpin is sitting on top of them rather than locked around the shank. This looks connected but can separate under load or over bumps, dropping the trailer. That is why the tug test and the visual under-trailer check are both required.
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Related questions on this topic
- What should you do with the air lines and electrical cord before pulling the tractor away from the trailer during uncoupling?
- When uncoupling, what does pulling the fifth wheel release handle to the open position do?
- After unlocking the fifth wheel jaws during uncoupling, how should you move the tractor?
- When raising the landing gear after coupling, what should you be aware of regarding the crank handle?
- Why should you use two low-pressure gears when starting to raise loaded landing gear rather than high gear?
- What should you check about the fifth wheel plate before backing under a trailer?
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