South Dakota CDL Permit Test - Knowledge Test Class A

Some older vehicles have front brake limiting valves with "normal" and "slippery" settings. Setting a brake limiting valve to "slippery" reduces the vehicle's stopping power, so a driver should make sure the valve is in its "normal" position. Front wheel braking has proven to be effective in all driving conditions.

Regrooved, recapped, or retreaded tires are prohibited on the front wheels of a bus.

A skid caused by over-acceleration can be resolved simply by removing your foot from the accelerator. Skids of this nature happen most frequently on surfaces covered in snow or ice.

Cargo should be inspected before beginning a trip, within the first 50 miles of the trip, and every three hours or 150 miles traveled thereafter. The driver of a truck transporting cargo is responsible for the cargo being safely secured throughout the trip.

To reduce the chances of becoming fatigued on a long trip, a driver should stop for a break at least once every two hours or 100 miles driven.

Always slow down before entering a foggy area. Use low beam headlights, avoid passing others, and avoid stopping on the side of the roadway. It is safest to completely avoid driving under foggy conditions, if possible.

Vehicles with air brakes are required to be equipped with a low pressure warning device. A wig wag is a type of low air pressure warning device. This device drops a mechanical arm into the driver's view if the pressure in the tanks drops to a level between 55 and 75 psi.