Oregon CDL Permit Test - Combination

Due to the "crack-the-whip" effect caused by rearward amplification, changing lanes too quickly in a combination vehicle can result in a rollover.

More than half of all accident-related truck driver deaths are a result of truck rollovers. To help prevent a rollover, be sure to load cargo low to the ground and centered on your rig. Take corners slowly and carefully.

When backing a vehicle with a trailer, you must turn the steering wheel in the direction opposite of where you want to go. Once your trailer starts to turn, you should turn the steering wheel the other way to follow the trailer.

When driving a vehicle with ABS, you should brake in the same manner as you would in a vehicle without ABS.

In vehicles equipped with an automatic tractor protection valve, the valve will pop out if air pressure drops to a level between 20 and 45 psi. When the valve pops out, the protection valve will close, stopping the flow of air.

Tractor protection controls in older vehicles may be operated by levers instead of knobs. If an air supply control is set in its "emergency" position, the air supply will be stopped and the trailer emergency brakes will be applied.

Because the weight of cargo gives them a higher center of gravity, fully-loaded rigs are 10 times more likely to roll over in a crash than empty rigs.