Oklahoma CDL DMV Endorsement Double 2

Because doubles and triples are more vulnerable than singles to jackknifing and rolling over, drivers should look far ahead of their vehicles so they can react to hazards well in advance and slow down or change lanes gradually.

Backing a CMV is always dangerous due to limited visibility, so using a helper to monitor your blind spots is encouraged whenever possible.

Spring brakes do not work on all axles. If your vehicle's spring brakes activate due to low pressure in an air brake system, your vehicle will need a longer distance to stop than usual, especially if you are carrying a heavy load.

If you are not certain that your vehicle will fit under overhead objects, you should slow down and take a different route, if possible.

Leaks in an exhaust system are extremely dangerous because they may allow toxic fumes into the cab or sleeper berth, endangering drivers and passengers.

Landing gear, or trailer supports, should always be completely raised before a vehicle is driven. Landing gear that is not entirely raised could catch on railroad tracks or other hazards on the roadway.

An Anti-Lock Braking System (ABS) helps prevent wheels from locking up during a hard application of brakes.

When inspecting a vehicle that is equipped with power steering, check the hoses, pumps, and fluid level. In particular, you should look for leaks in the hoses.

If your vehicle begins to hydroplane, you can regain control by releasing the accelerator and pushing in the clutch.

While driving downhill, you should hold down the brake pedal until your vehicle reaches a speed 5 mph below your safe speed, then release the brake pedal. Repeat this process.

Fully-loaded rigs are more vulnerable to rolling over than empty rigs because the weight of the cargo gives the vehicles higher centers of gravity.

At speeds below 40 mph, you should allow at least one second of following distance for every 10 feet of your vehicle. Follow the same formula when traveling at faster speeds, then add one additional second to your following distance. Remember that larger vehicles require more space to stop than smaller vehicles.

While regular mirror checks should be part of your normal scanning routine, be especially sure to check your mirrors when changing lanes.

The emergency air line controls the emergency brakes on a combination vehicle. A loss of air pressure in the emergency line will cause the emergency trailer brakes to activate.

When positioning trailers in a combination, the most heavily-loaded trailer should be the closest to the tractor. The lightest trailer should be positioned in the rear.

An air brake system has a safety relief valve, which releases air from the tanks if the pressure gets too high. If the valve must operate, something in the system is wrong and should be addressed by a mechanic.

When driving under foggy conditions, lights cannot be taken as a reliable indication of where the road is. The lights may be coming from a vehicle that has pulled off the road.

In heavy traffic, it is safest to match the speed of surrounding vehicles. Vehicles traveling in the same direction at the same speed are unlikely to collide. However, you should not exceed legal speed limits.

The most important reason to inspect your vehicle is to ensure the safety of yourself and other road users.

If brakes are overused, they can become too hot. This overheating causes them to fade, making them less effective at slowing the vehicle.