Alabama CDL DMV Endorsement Double 1

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.

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.

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

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.

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

When approaching your vehicle, you should check under the vehicle for fresh oil, coolant, grease, or fuel leaks. Spotting any of these before a trip is a cause for concern.

Traction is friction between your tires and the surface of the road. Adequate traction is necessary for braking and steering.

The service air line carries air and is controlled by either the foot brake or trailer hand brake. The service air line is attached to relay valves, which allow the trailer brakes to be applied quickly.

At times when visibility is low, you should turn your headlights on to the low beam setting. If you are having a difficult time seeing others, they are probably having a difficult time seeing you.

However you choose to deal with a brake failure on a downhill slope, it is important that you make your decision as quickly as possible. The longer you wait to act, the faster your vehicle will be moving, and the harder it will become to stop.

Having an Anti-Lock Braking System (ABS) on only the trailer, or even on just one axle, will still provide a driver with additional control over the trailer when braking.

If a federal or state inspector judges a CMV to be unsafe, they may put it out-of-service until it is fixed.

Many large vehicles have curved, convex mirrors. Convex mirrors allow drivers to see a wider area than flat mirrors. However, they also make objects seem smaller and farther away than they really are.

If your vehicle gets stuck on railroad tracks for any reason, you should immediately exit the vehicle and walk away from the tracks. Contact the proper emergency authorities.

The suspension system holds up the vehicle and its load while keeping the axles in place. Damage to a suspension system can be very dangerous.

To avoid rolling over and jackknifing, doubles and triples must be driven smoothly. To allow this, drivers should look well ahead of their vehicles so they can spot hazards early and have as much time as possible to make the necessary maneuvers.

To let drivers behind you know that you plan to slow down, lightly tap your brake pedal a few times to flash your brake lights. It is important to communicate your intentions to other drivers.

Be sure to test the trailer emergency brakes before beginning a trip. After ensuring that the trailer rolls freely, you can test the emergency brakes by pulling out the trailer air supply control, or placing it in the "emergency" position. Pull forward slightly with the tractor and make sure the trailer does not move.