District Of Columbia CDL DMV Endorsement Tank 1

You should approach every railroad crossing with the expectation that a train is coming. Do not rely on signals or your hearing to reliably tell you if a train is present. Always slow down when approaching a crossing. Never try to race a train.

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.

On newer vehicles, the trailer air supply control is an eight-sided red knob. It's used to control the tractor protection valve.

The suspension system keeps a vehicle's axles in place. Damaged suspension parts, such as leaking shock absorbers, may be potentially dangerous defects on a vehicle.

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

To drive safely, it is important to remember how much distance your vehicle will need to stop. Stopping distance for a vehicle can change with road conditions, weather conditions, and the quality of cargo in the vehicle's tanks.

Under wet conditions, roads are often most slippery when it first begins to rain. This is because the water mixes with oil and grease on the road that has not yet begun to wash away.

Use a floor lining when transporting Division 1.1, 1.2, or 1.3 materials. The floors should be tight and the liner must be made from either non-metallic material or non-ferrous metal. Non-ferrous metals are metals that do not contain iron or iron alloys.

If you are turning to avoid a hazard, do not apply the brakes while you are turning. This could easily lock the wheels and create a skid.

Except when parking briefly to perform necessary functions for vehicle operation (such as refueling), never park a vehicle carrying Division 1.1, 1.2, or 1.3 explosives within 300 feet of a bridge, tunnel, or building. Never park such a vehicle within five feet of the traveled portion of a road. Such vehicles should be parked only briefly.

Passing an accident scene can be hazardous because the people involved in the accident may not be watching traffic, and the scene itself may distract other passing drivers. Ice cream trucks can create hazardous conditions because they attract children who may not pay attention to nearby vehicles. Shoppers near the roadway are often paying attention to stores, not passing traffic.

Bobtail tractors are tractors that are not attached to any semitrailers. When operating a bobtail, you should be aware that stopping can be difficult and that it will take a longer distance to bring the bobtail to a complete stop than it would a tractor attached to a loaded semitrailer.

Shut-off valves are used in air supply lines to control the passage of air from one trailer to another. The rear shut-off valve should always be closed to prevent air from leaving the braking system.

It is essential that a driver always uses proper signals to make their intentions known to others on the road.

When a combination vehicle is lightly loaded, it may have poor traction. It is very easy for wheels to lock up on lightly-loaded vehicles when they are being stopped.

To check your vehicle's lights before a trip, you should set the parking brake, turn off the engine, remove the key from the ignition, and take the key with you. Turn on your low beam headlights and four-way flashers. Get out of the vehicle to make sure the lights are working properly.

When inspecting your tires, verify that there is at least 4/32 of an inch of tread depth in every major groove on the front tires, and tread depth of at least 2/32 of an inch on the other tires. Tires on the same vehicle should all be the same size.

Before a trip, you should ensure that air reaches all air brakes on all trailers by opening up the rear emergency line and service line shut-off valves to listen for escaping air. Close both shut-off valves before beginning to drive.

A coolant gauge rising above the highest safe temperature may indicate that there is a problem with the vehicle that could result in engine failure or a fire in the engine. Stop as soon as you safely can and investigate the problem.

When backing with a trailer, turn the top of the steering wheel in the direction opposite of where you want to go. Once the trailer begins turning, you should then switch the direction of the steering wheel to follow the trailer.