CDL - Combination Vehicle Practice Test

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CDL - Combination Vehicle Practice Test A tractor with a(n) ________ trailer requires the shortest amount of stopping distance . 1. empty 2. fully loaded 3. lightly loaded - ✔✔fully loaded Th ... e air leakage rate for a combination vehicle ( engine off, brakes on) should not be more than _____ psi per minute . 1. 4 2. 6 3. 2 - ✔✔4 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 driving 2. your fuel usage will increase 3. tire pressure will drop - ✔✔you could lose your brakes while driving Which part of the kingpin should the locking jaws close around? - ✔✔The shank Glad hands are used to connect the .... 1. kingpin from the trailer to the locking jaws of the fifth wheel 2. electrical lines from the tractor to the trailer 3. 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 Trucks roll over more easily when fully loaded and are 1. ten times more likely to roll over in a crash than empty rigs 2. five times more likely to roll over in a crash than empty rigs 3. 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 In general, the higher your trucks center of gravity, the ... 1. easier it is to turn over 2. more stable it is when turning 3. easier it is to turn around corners - ✔✔easier it is to turn over You are driving a combination vehicle when the trailer breaks away, pulling apart both air lines. You would expect the trailer brakes to come on and ... 1. the tractor to lose all air pressure 2. the tractor protection valve to close 3. the trailer supply valve to stay open - ✔✔the tractor protection valve to close When you drive a set of doubles, which shut-off valve must be closed in the last trailer? 1. Middle section 2. front section 3. back section - ✔✔back section 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 away 2. the trailer will not swivel on the fifth wheel 3. 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 What gear should the tractor engine be in after you uncouple the trailer and are inspecting the trailer? 1. neutral 2. low reverse 3. high reverse - ✔✔neutral 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 pedal 2. applying and releasing the trailer brakes and listening for brake sounds 3. 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 connections 3. 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 the 1. trailer tank pressure to be lost 2. trailer emergency brakes to come on 3. tractor spring brakes to lock on - ✔✔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 should 1. immediately apply your tractor parking brakes 2. begin to lower the trailer landing gear 3. back up gently and ease pressure on the fifth wheel locking jaws - ✔✔back up gently to ease pressure on the fifth wheel locking jaws When should you use the hand valve to park a combination vehicle? 1. To park at loading docks 2. To park on a grade 3. never - ✔✔Never The front trailer supports are up, and the trailer is resting on the tractor. Make sure that 1. there is enough clearance between the upper and lower fifth wheel 2. there is enough clearance between the tractor frame and the landing gear 3. the safety latch is in the unlocked position - ✔✔there is enough clearance between the tractor frame and the landing gear 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 brakes 3. all the above - ✔✔all the above Where should the tractor be when you inspect the landing gear after uncoupling the trailer? 1. With the fifth wheel directly beneath the kingpin 2. completely cleared from the trailer 3. with the tractor frame under the trailer - ✔✔with the tractor frame under the trailer After you lock the kingpin into the fifth wheel, you should check the connection by pulling 1. the tractor ahead gently with the trailer brakes locked 2. forward 50 feet, then turning right, and then left 3. 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 ________ at the extreme end of the load. 1. red lights 2. red flags 3. a red flag - ✔✔red lights Which type of truck-trailer combination has the greatest chance of a "crack-the-whip" rollover? 1. A tractor pulling three trailers 2. A single tractor trailer 3. A tractor pulling two trailers - ✔✔A tractor pulling 3 trailers Air and electrical lines from the tractor to the trailer should be... 1. pulled tight with very little slack 2. secured but with enough slack for turns 3. resting on the frame of the tractor. - ✔✔secured but with enough slack for turns Compared with a straight truck or bus, there are ________ things to inspect in combination vehicles. 1. fewer 2. more 3. the same number of - ✔✔more What is the emergency air line for? 1. To engage the trailer brakes in case of air pressure loss 2. To have extra air pressure in case you need it 3. To engage the front brakes of the tractor in case of an emergency - ✔✔To engage the trailer brakes in case of air pressure loss The tractor protection valve will close and the trailer _______ brakes will come on when there is a major leak in the brake line. 1. parking 2. service 3. emergency - ✔✔emergenc [Show More]

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