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What is trailer service line?

Connecting a trailer One connection carries air to fill the trailer’s tanks and is called the supply or emergency line. The other carries pressure for the service brakes and is called the service line.

What color is the service line on a tractor trailer?

blue

What is the purpose of the service Air Line?

The Service Air Line controls the service brakes when you use the brake pedal. The Emergency Air Line supplies air to the trailer air tanks and the emergency brakes.

What does the trailer air supply control do?

The trailer air supply control on newer vehicles is a red eight-sided knob, which you use to control the tractor protection valve. You push it in to supply the trailer with air, and pull it out to shut the air off and put on the trailer emergency brakes.

What does the trailer air supply control look like?

What does the trailer air supply control look like? A. It is a square blue knob. On newer vehicles, the trailer air supply control is an eight-sided red knob.

Why should you not use the trailer hand valve?

The trailer hand valve (“Trolly Valve” or “Johnson Bar”) operates only the trailer brakes. It should only be used to test the trailer brakes. Do not use the trailer hand valve while driving. This could cause the trailer brakes to lock up, and then cause the trailer to skid or jackknife.

What two things can a driver do to prevent rollovers?

The truck becomes easier to turn over. Fully loaded rigs are 10 times more likely to roll over in a crash than empty rigs. Two things will help prevent rollover: keeping the cargo as close to the ground as possible, and going slowly while turning.

Why should you lock the trailer glad hands or dummy couplers to each other when you are not towing a trailer?

Why should you lock the tractor glad hands (or dummy couplers) to each other when you are not towing a trailer? A The connected brake circuit becomes a back up air tank. B If you did not, you could never build system pressure.

What should the trailer height be before you connect a converter dolly to a second or third trailer?

When connecting a converter dolly to a second trailer, the trailer height should be ____ the center of the fifth wheel. When connecting a converter dolly to a second or third trailer, the trailer height should correct. It should be slightly lower than the center of the fifth wheel.

At what angle do you connect your glad hand connections to the trailer?

When connecting the glad hands, press the two seals together with the couplers at a 90 degree angle to each other. A turn of the glad hand attached to the hose will join and lock the couplers. If you do cross the air lines, supply air will be sent to the service line instead of going to charge the trailer air tanks.

What should you do to stop a trailer skid?

  1. Quickly steer in the opposite direction you want the vehicle to go.
  2. Engage the parking brake so all wheels have even brake pressure.
  3. Accelerate out of the skid.
  4. Let the vehicle slow down without turning or braking hard.

What are the most common causes of a trailer jackknife?

What Causes a Semi-Truck to Jackknife?

  • Brakes. There are a variety of reasons a jackknife accident can occur, including improper brake maintenance.
  • Speeding. Speeding can also lead to a jackknife accident.
  • Road Conditions. Slippery roads, caused by rain or snow, can also cause trucks to jackknife.
  • Cargo.

What gear should the tractor engine be in after you uncouple the trailer and are inspecting the trailer supports?

CDL

Question Answer
What gear should the tractor engine be in after you uncouple the trailer and are inspecting the trailer supports? Neutral
You have coupled with a semitrailer. Where should you put the iron trailer supports before driving away? Fully raised with the crank handle secured in its bracket.

What are 4 different types of skids?

Driver Ed: Chapter 13 – Natural Laws and Risk Management

A B
Cornering Skid You lose steering control in a turn, and the car begins to skid
Blowout Skid tire suddenly loses air pressure, and the car begins to skid.
List the four different types of skids. Braking, Power, Cornering and Blowout

Which lights Cannot be checked at the same time?

Which of these lights cannot be checked at the same time? Turn signals, brake lights, and four-way flashers.

What does not affect your choice of gears?

Which of these does NOT affect your choice of gears? Tire tread type. You wish to turn right from a two-lane, two-way street into another.

What is the best advice when entering fog?

3 Tips for Driving in Fog

  1. Slow down. Driving at normal speeds in fog can be very dangerous.
  2. Always headlights, never brights. Avoid using high-beam headlights in fog as fog consists of tiny water droplets that spread and reflect light.
  3. Stay focused on the road. Driving in fog is not a time for multi-tasking.

When entering a foggy area you should?

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.

When driving in fog you should never use your high beams because?

Use fog lights if you have them. Never use your high-beam lights. Using high beam lights causes glare, making it more difficult for you to see what’s ahead of you on the road. Leave plenty of distance between you and the vehicle in front of you to account for sudden stops or changes in the traffic pattern.

What is the best advice for driving in heavy fog CDL?

Slow down before you enter fog. 3. Use low-beam headlights and fog lights for best visibility even in daytime, and be alert for other drivers who may have forgotten to turn on their lights.

When entering an expressway your car’s speed should?

Explanation : You must obey the posted speed limit, or, if no limit is posted, drive no faster than 55 mph (88 km/h). the legal limit on an icy or foggy expressway might be 55 mph (88 km/h), but the safe speed to drive would be much lower.

Should you drive in heavy fog?

Dense fog can create dangerous conditions on the road, especially if it’s extremely dense fog or combined with other severe weather conditions. The safest thing to do is pull over into a parking area until the fog clears.

When should you follow a large truck or tractor trailer?

In crashes, large trucks most often hit the vehicle in front of them. Did You Know? If you are driving below 40 mph, you should leave at least one second for every 10 feet of vehicle length. For a typical tractor-trailer, this results in 4 seconds between you and the leading vehicle.