Alabama CDL Permit Test - Double

A dolly equipped with an Anti-Lock Braking System (ABS) is required to have a yellow malfunction lamp located on its left side.

Before driving a vehicle with air brakes, you should ensure that the spring brakes come on automatically when air tank pressure falls to a level between 20 and 45 psi. You can do this by chocking the wheels and releasing air from the braking system by stepping on and off the brake pedal. Once the pressure levels drop to an unsafe level, the parking brake valve should pop out and spring brakes should come on.

Driving while distracted may result in slowed perception, delayed decision-making, and improper actions. Watch for distracted drivers and avoid them, when possible.

A vehicle will be slowed down by gravity on any uphill grade. You may need to switch to a lower gear to climb a steep grade.

To prevent the build up of oil and water in a vehicle's air tanks, manually operated air tank drains should be used at the end of each day of driving.

If you observe a crash involving an aggressive driver, you should stop a safe distance from the crash scene, wait for police to arrive, and inform them of the aggressive behavior you witnessed.

Increasing your vehicle's speed will increase your vehicle's striking power and braking distance. Doubling your vehicle's speed from 20 to 40 mph will multiply its braking distance by four.