CDL - Combination Vehicle Practice Test Flashcards

CDL - Combination Vehicle Practice Test Flashcards You should use chocks when parking a trailer without spring brakes because1. if the air supply leaks away, there will be no brakes2. some states require chocking of trailer wheels3. you dont want the trailer rolling down a hill if the air supply leaks away, there will be no brakes When you are uncoupling a loaded trailer, lower the landing gear until it ...1. reaches the ground2. makes firm contact with the ground3. makes contact with the ground, and leave the trailer off the fifth wheel makes firm contact with the ground The trailer hand valve works the trailer brakes. Which of these statements is true?1. the foot brake sends air to all the brakes on the vehicle ( including the trailer(s))2. The trailer hand valve should be used only to test the trailer brakes3. all the above all the above When backing a tractor under a trailer, you should expect that1. the trailer will be lifter slightly when the tractor backs under it2. the trailer landing gear is fully extended3. the end of the kingpin is even with the top of the fifth wheel the trailer will be lifting slightly when the tractor backs under it Where should the tractor be when you inspect the landing gear after uncoupling the trailer?1. With the fifth wheel directly beneath the kingpin2. completely cleared from the trailer3. with the tractor frame under the trailer with the tractor frame under the trailer Trucks roll over more easily when fully loaded and are1.ten times more likely to roll over in a crash than empty rigs2. five times more likely to roll over in a crash than empty rigs3. two times more likely to roll over in a crash than empty rigs ten times more likely to roll over in a crash than empty rigs Air and electrical lines from the tractor to the trailer should be...1. pulled tight with very little slack2. secured but with enough slack for turns3. resting on the frame of the tractor.secured but with enough slack for turns When checking the trailer emergency brakes, make sure that the tractor protection control valve is placed in the _______ position.1. normal2. emergency3. neutral emergency A tractor with a(n) ________ trailer requires the shortest amount of stopping distance .1. empty2. fully loaded3.lightly loaded fully loaded You are uncoupling a trailer. After you shut off the trailer air supply and lock the trailer brakes, you should1.immediately apply your tractor parking brakes2. begin to lower the trailer landing gear3. back up gently and ease pressure on the fifth wheel locking jaws back up gently to ease pressure on the fifth wheel locking jaws

After you have coupled the trailer, you should start to raise the landing gear by using1. low gear2. high gear3.intermediate gear low gear The fifth wheel locking lever is not locked after the jaws close around the kingpin. This means that1. the parking lock is off and you may drive away2. the coupling is not right and should be fixed before you drive the coupled unit3. the trailer will not swivel on the fifth wheel the coupling is not right and should be fixed before you drive the coupled unit Which part of the kingpin should the locking jaws close around?The shank You are coupling a tractor to a semi-trailer. You have backed up but are not yet under it. Before backing under the semi trailer, you should hook up1. the electrical service cable2. nothing. Back up and lock the fifth wheel3. The emergency and service air lines the emergency and service air lines A trailer is most likely to jackknife when it is ...1. loaded to full capacity2. overloaded3. empty empty In general, the higher your trucks center of gravity, the ...1.easier it is to turn over2. more stable it is when turning3.easier it is to turn around corners easier it is to turn over How much space should there be between the upper and lower fifth wheel after coupling?1. Just enough to see light through it2. About 1/4 inch3. None none Glad hands are used to connect the ....1. kingpin from the trailer to the locking jaws of the fifth wheel2. electrical lines from the tractor to the trailer3. service and emergency air lines from the truck or tractor to the trailer service and emergency air lines from the truck or tractor to the trailer The tractor protection valve will close and the trailer _______ brakes will come on when there is a major leak in the brake line.1. parking2. service3. emergency emergency When you drive a set of doubles, which shut-off valve must be closed in the last trailer?1. Middle section2. front section3. back section back section The air leakage rate for a combination vehicle ( engine off, brakes on) should not be more than _____ psi per minute

.1. 42. 63. 2

4 What gear should the tractor engine be in after you uncouple the trailer and are inspecting the trailer?1.neutral2. low reverse3. high reverse neutral If you do not do the final air brake check for air leaks and fix them before driving,1. you could lose your brakes while driving2. your fuel usage will increase3. tire pressure will drop you could lose your brakes while driving Which type of truck-trailer combination has the greatest chance of a "crack-the-whip" rollover?1. A tractor pulling

three trailers2. A single tractor trailer3. A tractor pulling two trailers A tractor pulling 3 trailers

After you supply air to the trailer, make sure the air lines are not crossed and the trailer brakes are working. This is done by ..1. lifting the brake pedal2. applying and releasing the trailer brakes and listening for brake sounds3. turning on the parking brake from the cab applying and releasing the trailer brakes and listening for brake sounds If the brakes did not release when you pushed the trailer air supply valve, you should ...1. cross the air lines,2. check the air line connections3. check the electrical cables check the air line connections You have a major leak in the service line, and you apply the brakes. Service air pressure will escape and cause the1. trailer tank pressure to be lost2. trailer emergency brakes to come on3. tractor spring brakes to lock on trailer emergency brakes to come on When you drive a set of doubles, which shut0off valve must be closed in the last trailer?1. front2. back3. middle back The fifth wheel locking lever is not locked after the jaws close around the kingpin. This means that...1. the parking lock is off and you may drive away2. the trailer will not swivel on the fifth wheel3. the coupling is not right and should be fixed before you drive the coupled unit the coupling is not right and should be fixed before you drive the coupled unit The front trailer supports are up, and the trailer is resting on the tractor. Make sure that1. there is enough clearance between the upper and lower fifth wheel2. there is enough clearance between the tractor frame and the landing gear3.the safety latch is in the unlocked position there is enough clearance between the tractor frame and the landing gear What is the emergency air line for?1. To engage the trailer brakes in case of air pressure loss2. To have extra air pressure in case you need it3. To engage the front brakes of the tractor in case of an emergency To engage the trailer brakes in case of air pressure loss While you are driving, your emergency air line breaks or gets pulled apart. The loss of pressure will cause the1. air compressor to unload instead of pumping air2. trailer emergency brakes to come on3. trailer supply valve to open trailer emergency brakes to come on You are uncoupling a trailer. After you shut off the trailer air supply and lock the trailer brakes, you should1. begin to lower the trailer landing gear2. immediately apply your tractor parking brakes3. back up gently to ease pressure on the fifth wheel locking jaw back up gently to ease pressure on the fifth wheel locking jaw After you lock the kingpin into the fifth wheel, you should check the connection by pulling1. the tractor ahead gently with the trailer brakes locked2. forward 50 feet, then turning right, and then left3. the tractor ahead sharply to release the trailer brakes the tractor ahead gently with the trailer brakes locked At night, when a vehicle is carrying a load that extends four feet or more beyond the rear of the body, there must be