CDL Doubles and Triples Practice Test 3

Question 1

When making a quick lane change with doubles, what is the main danger?

Accepted Answer

The rear trailer can roll over or swing into another lane

Answer

Sudden steering amplifies sway in the rear trailer, risking rollover or a lane intrusion.

Question 2

Why should you inspect the air lines on a converter dolly carefully?

Accepted Answer

Air leaks or crossed lines can cause brake failure

Answer

Damaged or improperly connected air lines can prevent the dolly and rear trailer brakes from working.

Question 3

How can you check that the second trailer's kingpin is locked into the dolly's fifth wheel?

Accepted Answer

Pull gently against the pin with the dolly secured and inspect the locking jaws

Answer

A gentle pull test plus visual inspection of the locking jaws confirms a secure kingpin coupling.

Question 4

What is the correct order when coupling doubles to keep trailers from rolling?

Accepted Answer

Secure the second trailer brakes before backing the dolly under it

Answer

Setting the second trailer's brakes prevents it from rolling while you position the dolly under it.

Question 5

Which axles are most likely to lock up first on an empty doubles combination during hard braking?

Accepted Answer

The lightly loaded trailer axles

Answer

Lightly loaded or empty trailer axles have less traction and can lock up sooner during hard braking.

CDL Practice Test