Note: Your are not logged in. We can not keep your scores or track your progress unless you Register and Log In

6.4 – Coupling and Uncoupling (continued)

Step 9: Lock Trailer Brakes

  • Pull out the “air supply” knob or move the tractor parking valve control from “normal” to “emergency.”

Step 10: Back Under Trailer

  • Use lowest reverse gear.
  • Back tractor slowly under trailer to avoid hitting the kingpin too hard.
  • Stop when the kingpin is locked into the fifth wheel.

Step 11: Check Connection for Security

  • Raise trailer landing gear slightly off ground.
  • Pull tractor gently forward while the trailer brakes are still locked to check that the trailer is locked onto the tractor.

Step 12: Secure Vehicle

  • Put transmission in neutral.
  • Put parking brakes on.
  • Shut off engine and take keys with you so someone else does not move truck while you are under it.

Step 13: Inspect Coupling

  • Use a flashlight, if necessary.
  • Make sure there is no space between upper and lower fifth wheel. If there is space, something is wrong (kingpin may be on top of the closed fifth-wheel jaws, and trailer would come loose very easily).
  • Go under trailer and look into the back of the fifth wheel. Make sure the fifth wheel jaws have closed around the shank of the kingpin.
  • Check that the locking lever is in the “lock” position.
  • Check that the safety latch is in position over locking lever. (On some fifth-wheels, the latch must be put in place by hand.)
  • If the coupling is not right, do not drive the coupled unit; get it fixed.

Step 14: Connect the Electrical Cord and Check Air Lines

  • Plug the electrical cord into the trailer and fasten the safety latch.
  • Check both air lines and electrical line for signs of damage.
  • Make sure air and electrical lines will not hit any moving parts of vehicle.

Step 15: Raise Front Trailer Supports (Landing Gear)

  • Use low gear range (if so equipped) to begin raising the landing gear. Once free of weight, switch to the high gear range.
  • Raise the landing gear all the way up. (Never drive with landing gear only part way up as it may catch on railroad tracks or other things.)
  • After raising landing gear, secure the crank handle safely.
  • When full weight of trailer is resting on tractor:
    • Check for enough clearance between rear of tractor frame and landing gear. (When tractor turns sharply, it must not hit landing gear.)
    • Check that there is enough clearance between the top of the tractor tires and the nose of the trailer.

Step 16: Remove Trailer Wheel Chocks

  • Remove and store wheel chocks in a safe place.

Multiple-Choice Questions:

Question #344 (1 of 1)

Give a brief explanation of the problem:

Optional: Leave your email address if you would like a reply:

Report Cancel

After backing the tractor under the trailer and connecting to the trailer, how much space should be in between the 5th wheel and the trailer apron?

  • No space
  • A minimum of two inches
  • About 1/2 inch to 1 inch
  • At least 1 inch
Make sure there is no space between upper and lower fifth wheel. If there is space, something is wrong (kingpin may be on top of the closed fifth-wheel jaws, and trailer would come loose very easily)
This question will not be on the test, but it's very important in real life. You must make sure there is not a gap between the 5th wheel and the trailer. If there is space, something isn't hooked up properly and you must fix it before moving the trailer.

Why Join Trucking Truth?

We have an awesome set of tools that will help you understand the trucking industry and prepare for a great start to your trucking career. Not only that, but everything we offer here at TruckingTruth is 100% free - no strings attached! Sign up now and get instant access to our member's section:
High Road Training Program Logo
  • The High Road Training Program
  • The High Road Article Series
  • The Friendliest Trucker's Forum Ever!
  • Email Updates When New Articles Are Posted

Apply For Paid CDL Training Through TruckingTruth

Did you know you can fill out one quick form here on TruckingTruth and apply to several companies at once for paid CDL training? Seriously! The application only takes one minute. You will speak with recruiters today. There is no obligation whatsoever. Learn more and apply here:

Apply For Paid CDL Training