When preparing to couple a converter dolly to a second (rear) trailer that has NO spring brakes, what is the correct sequence to secure that trailer before working around it?

Immediately chock the wheels without connecting any air lines, since a trailer without spring brakes cannot be charged

Connect only the service line to apply the brakes, then leave the emergency line disconnected the entire time

Lower the landing gear fully first, then connect both air lines and leave them connected while coupling the dolly

Coupling & Uncoupling Practice Test

✓

Correct!

Correct. Per the AAMVA CDL Manual: drive the tractor close to the trailer, connect the emergency line, charge the trailer air tank, then disconnect the emergency line to set the trailer's emergency brakes (assuming slack adjusters are correctly adjusted). Chock the wheels if there is any doubt.

✗

Not quite.

Wrong. This skips charging the trailer air tank first. Without charging the tank, there is no reserve air to hold the emergency brakes once set, and chocking wheels is only called for additionally 'if there is any doubt' - it does not replace the air-charging procedure.

The correct answer is A: Drive the tractor close to the trailer, connect the emergency line, charge the trailer air tank, then disconnect the emergency line to set the trailer's emergency brakes.

✗

Not quite.

Wrong. The documented procedure uses the emergency line, not the service line, to charge the tank and then set the emergency brakes on a trailer without spring brakes. The service (trolley) line only controls brakes while connected and operated, it does not set parked emergency brakes.

The correct answer is A: Drive the tractor close to the trailer, connect the emergency line, charge the trailer air tank, then disconnect the emergency line to set the trailer's emergency brakes.

✗

Not quite.

Wrong. Landing gear position is unrelated to securing the rear trailer's brakes before coupling the dolly underneath it, and the procedure calls for disconnecting - not leaving connected - the emergency line after charging, since that disconnection is what actually sets the brakes.

The correct answer is A: Drive the tractor close to the trailer, connect the emergency line, charge the trailer air tank, then disconnect the emergency line to set the trailer's emergency brakes.