Coupling and uncoupling, step by step
Section 6.4 of the Mississippi CDL Manual (p. 6-7) gives the steps for coupling and uncoupling a tractor-trailer. It is tested on the Combination Vehicles test.
Key facts
| Part of | the Combination Vehicles test (80% to pass) | 49 CFR 383.135 |
|---|---|---|
| Manual section | §6.4 Coupling and uncoupling | MS CDL Manual p. 6-7 |
| Questions in CDL Mile's bank | 20 | CDL Mile, checked against MS CDL Manual |
Key rules
- § 6.4.4p. 6-11
Before extending the jack, check that the ground beneath the jack pad can carry the weight of the trailer tongue. By this point the electrical connector, breakaway lanyard and safety chains are already disconnected and the coupler is open.
Uncoupling a Pintle Hook
- § 6.4.2p. 6-9
When you unlock the fifth wheel, keep your legs and feet away from the tractor's rear wheels. If the vehicle moves, you could be seriously hurt.
Uncoupling Tractor-Semitrailers
- § 6.4p. 6-10
After you push the pintle hook latch closed, the lock handle should rotate and rise until it sits flush with the top of the latch. Then insert the tethered lock pin, if there is one.
Coupling and uncoupling
- § 6.4.1p. 6-9
Once the trailer's full weight rests on the tractor, make sure there is room between the back of the tractor frame and the landing gear. In a sharp turn, the tractor must not strike the landing gear.
Coupling Tractor-Semitrailers
- § 6.4.2p. 6-9
Stopping with the frame under the trailer is a safety backup. If the landing gear collapses or sinks, the tractor frame keeps the trailer from falling to the ground.
Uncoupling Tractor-Semitrailers
Try two questions
Combination Vehicles · Coupling and uncoupling
In the manual's steps for coupling a gooseneck hitch, what do you do before lowering the trailer's coupler onto the ball?
Tap an answer to see the explanation and the manual page.
Combination Vehicles · Coupling and uncoupling
When coupling a ball-type drawbar, what does the manual say if the safety cover bar fails to seat properly in its housing?
Tap an answer to see the explanation and the manual page.
More Combination Vehicles topics
Sources
Mississippi Commercial Driver's License Manual, version March 2025, Mississippi Department of Public Safety. Page references are to its printed page numbers. CDL Mile is independent and not affiliated with Mississippi DPS.
Updated for the March 2025 Mississippi CDL manual. Last checked November 5, 2026.
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