Pre-Trip Inspection: Coupling

4 questions in the bank cover this topic. Everything below is drawn from the sources those questions cite.

Sources: 49 CFR 396 Appendix A

What you need to know

3/8 inch.

That pin carries the pitching of the whole trailer over every bump, so wear there grows quickly once it starts.

More than 3/8 inch horizontal movement between pivot bracket pin and bracket.

49 CFR 396 Appendix A

The same 3/8 inch as the pivot bracket.

A slider that moves beyond this is shifting your weight distribution while you drive.

Movement more than 3/8 inch between slider bracket and slider base.

49 CFR 396 Appendix A

All three.

The fore and aft stops matter most: without them a slider that unlatches does not merely move, it can run off its track entirely.

Any latching fasteners missing or ineffective.

Any fore or aft stop missing or not securely attached.

49 CFR 396 Appendix A

All three, and note the wording on the second: ANY movement, not excessive movement.

The mount should be rigid, so motion there is already failure.

Any fasteners missing or ineffective.

Any movement between mounting components.

Any mounting angle iron cracked or broken.

49 CFR 396 Appendix A

Check yourself

• What is the maximum horizontal movement between the pivot bracket pin and bracket?

• What is the maximum movement between your slider bracket and slider base?

• What are the slider conditions that put a fifth wheel out of service?

• What must you check where the fifth wheel mounts to the frame?

Answers are in the practice test for this topic.