Alabama Tanker CDL Test 2

A trailer tends to swing around, potentially resulting in a trailer jackknife, if its wheels lock up.

Before a trip, be sure to inspect all couplings. There should be no space between the upper and lower fifth wheel.

Always downshift before beginning to drive downhill. Forcing an automatic transmission into a lower gear at a high speed could damage the transmission and also lead to a loss of ability to engine brake. Drive at a speed that will allow you to control your vehicle without overusing your brakes. When determining a safe speed to drive, you should take into account the steepness of the grade, the length of the grade, the weight of your vehicle, road conditions, and weather conditions.

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.

On many vehicles, multi-speed rear axles and auxiliary transmissions are used to provide extra gears. They are usually controlled by a selector knob on the gearshift lever.

The securement of cargo must be checked before beginning a trip, within the first 50 miles of a trip, and then again every three hours or 150 miles.

Combination vehicles are usually heavier and longer than single commercial vehicles. For these reasons, they usually require more driving skill than single commercial vehicles.

To reduce the risk of a rollover, the weight of cargo in a trailer should be kept as low to the ground as possible. Weight should not be placed primarily on one side of the trailer as this could make the trailer lean, increasing the risk of a rollover.

Press the brake pedal down smoothly and gradually every time you slow or stop. The amount of brake pressure you need to apply depends on the speed of your vehicle and how quickly you need to stop.

Black ice is a thin layer of ice that is clear enough for the road surface to be seen through it. A road covered in black ice may look like it is merely wet. You should be very careful when temperatures are below freezing and the road looks wet.