Rhode Island CDL Permit Test - Double

If you must drive so slowly that you will impede the flow of traffic, you should turn on your four-way flashers to alert drivers behind you (as long as local laws allow the use of flashers).

The trailer hand valve (also referred to as the trolley valve or Johnson bar) is a mechanism that works the trailer brakes. It should only be used to test the brakes. Using it while the vehicle is being driven could cause a skid. Never use the trailer hand valve while parking because doing so may release the air pressure from the braking system, releasing the brakes that are holding the vehicle in place.

When backing up to couple a trailer, you should position the tractor directly in front of the trailer. Trying to couple while backing at an angle could cause the trailer to move and the landing gear to break.

In single air systems, air pressure should build from approximately 50 to 90 psi within three minutes.

It is important to inspect your tires before every drive. Rust around wheel nuts may indicate that they are loose.

When backing with a trailer, begin by turning the steering wheel in the direction opposite of the turn. Once the trailer starts to turn, reverse the direction of the steering wheel to follow the trailer.

Making a sudden lane change can be dangerous while driving a combination vehicle. You can avoid the need to make a sudden lange change by looking down the road for upcoming obstacles that will require you to change lanes.