CDL Combination Vehicles

How should you test the tractor semi trailer combination for being properly coupled?
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How should you test the tractor semi trailer combination for being properly coupled?
Pull gently forward in low gear against the locked trailer brakes, then inspect your coupling.
When coupling to the trailer, how far do you back up before stopping the first time?
Until the fifth wheel plate just touches the trailer.
What do you check before backing under the trailer?
Make sure the trailer brakes are set.
Air lines on a combination vehicle are often colored to keep them from getting mixed up. What color is the emergency line and what color is the service line?
Red and blue.
After you back up to the trailer and the fifth wheel plate touches the trailer, you set the tractor park brake, get out and hook up the emergency and service air lines. Then what do you do before backing under the trailer?
Supply air to the trailer system, then pull out the trailer air supply knob to fully set the trailer brakes.
What three things can you do to prevent rollovers?
Keep your load centered, keep the load as low in the trailer as possible, and go slow around turns.
How far do you raise the landing gear on your trailer?
Crank it up as far as it will go.
You have coupled with a semi trailer. In what position should you put the landing gear before driving away?
Fully raised with the crank handle secured in its bracket.
When uncoupling, what could happen if you park the trailer at an angle?
You could do damage to the landing gear and dolly legs.
Why should you lock the tractor glad hands together or couple them to the dummy glad hands when bobtailing?
It will keep dirt and water out of the lines.
When backing under a trailer, you should expect the trailer to be lifted slightly by the fifth wheel plate.True.Before you begin coupling, you should check your travel path for obstacles and hazards.True.What should your air supply pressure gauge read before backing under a trailer?100 - 125 psi.In case of a jackknife situation, you can use your trailer hand valve to apply trailer brakes to stop the trailer from skidding.False.Which knob do you actuate to supply air to your trailer?Push in on the tractor protection valve knob, which is the red knob.Do combination vehicles take longer to stop when they are empty or loaded?When they are empty.What three things do you check after coupling to a trailer?Check that there is no gap between the fifth wheel plate and the trailer apron, check that the release handle is all the way in and latched, and check with a flashlight that the fifth wheel jaws have locked around the kingpin.Bobtail tractors will stop shorter than a combination vehicle loaded to maximum gross weight.False.If you back under a trailer at an angle rather than from straight on, you could damage the landing gear.True.When you go around a corner and your trailer "off-tracks", what is happening?The trailer wheels follow a different path than the tractor wheels.When should you use the hand valve to park a combination vehicle?Never.If the service air line comes apart while you are driving a combination vehicle but the emergency line stays together, what will happen right away?Nothing is likely to happen until you try to apply your brakes.What is the device which connects the service and emergency air lines from the tractor to the trailer called?Glad hands.What is the purpose of the tractor protection valve?It keeps the tractor from losing all its air in an emergency.What is the earliest way to notice a trailer skid?You will see the side of the trailer in your mirror.If you hook up to an old trailer and you cross your air lines, what will happen?If the trailer doesn't have spring brakes, you will be able to pull the trailer but you won't have any trailer air brakes.During your pre-trip inspection, the fifth wheel should be checked for what?To see if there is damage or loose or missing parts, to see that it is properly greased, and to verify that the jaws are open.What should you do when coupling the glad hands together?Clean the rubber seals for dirt, press the two seals together at a 90 degree angle, match red to red and blue to blue, firmly rotate the connector to lock it into place.You are coupling a tractor to a semi trailer and have backed up to the trailer but you are not under it. What should you hook up before backing under?The emergency and the service air lines.You are driving a combination vehicle and the trailer breaks away pulling apart both air lines. You would expect the trailer brakes to come on. What would you expect to happen to the tractor brakes?The tractor protection valve should close and allow you to have enough air in the system to stop the tractor.Why should you be sure that the fifth wheel plate is greased?To prevent steering problems.How do you line up when you are getting ready to back under a semi trailer?Directly in front of the trailer so you can back under squarely and not on an angle.How do you release the tractor parking brakes?Push in on the parking brake knob.What does the parking brake knob look like?It is yellow and diamond shaped.What does the tractor protection valve or the trailer air supply knob look like?It is red and octagonal (8 sided).What is common about trailers that were made before 1975?They usually do not have spring brakes.What do you do if you are braking and your trailer goes into a skid?Release the pressure on the service brake (brake pedal) to get traction back to the trailer wheels.When you are traveling under 40 mph on dry roads, how much minimum following distance do you need to maintain?One second for every 10 feet of your vehicle's length.If you are driving a 60 foot vehicle at 55 mph on dry roads, what should your minimum following distance be?Seven seconds. (one second for every 10 feet of vehicle length and add one second if going over 4o mph.What is the king pin?A pin attached to the underside of a trailer on the apron that engages the fifth wheel assembly on the tractor to couple the trailer to the tractor.Which brake system is activated with the foot pedal?The service brake.You are preparing to back under a semi trailer with your tractor. The trailer is at the correct height when it will be raised slightly as you back under it.True.You should only use your hand valve to park at a loading dock.False.When do you use your hand valve?Only when testing your trailer brakes.Which part of the king pin should the fifth wheel jaws close around?The shank.