Coupling & UncouplingQuestion 1 of 60
Before backing a tractor under a trailer, where should the trailer be positioned relative to the fifth wheel?
a.Slightly higher than the fifth wheel so it can slide up as you back
b.Low enough that the trailer is raised slightly by the tractor as you back under it
c.At the exact same height so no lifting occurs
d.Below the frame rails so the kingpin drops in freely
Explanation
The trailer should be low enough that it is raised slightly when the tractor backs under it. This ensures the fifth wheel makes solid contact and the kingpin seats properly. If the trailer is too low the tractor may hit and damage the nose; too high and it can miss the fifth wheel.
Practice all 60 questions free — no signup required.
Related questions on this topic
- What is the correct order for positioning the tractor before coupling to a trailer?
- Before backing under a trailer, the fifth wheel should be tilted how?
- When connecting the glad hands, what must you check to avoid a dangerous coupling mistake?
- After the kingpin has locked into the fifth wheel, how should you test that the coupling is secure?
- After the tug test, why should you go under the trailer and look into the back of the fifth wheel?
- When should the locking jaws be closed around the kingpin?
Last reviewed: · editorial process
PrepPass Editorial Team · Verified against CDL Combination Vehicles Knowledge Test · How we review