CDL Combination Vehicle Practice Test Questions & Answers Latest 2024/2025 | 100% Correct

A tractor with a(n) ________ trailer requires the shortest amount of stopping distance . 1. empty 2. fully loaded 3. lightly loaded - correct answersfully loaded The 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 - correct answers4 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 - correct answersyou could lose your brakes while driving Which part of the kingpin should the locking jaws close around? - correct answersThe 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 - correct answersservice 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 - correct answersten 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 - correct answerseasier 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 CDL Combination Vehicle Practice Test Questions & Answers Latest 2024/2025 | 100% Correct 3. the trailer supply valve to stay open - correct answersthe 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 - correct answersback 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 - correct answersthe 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 - correct answersneutral 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 - correct answersapplying 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 - correct answerscheck 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 - correct answerstrailer 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 - correct answersback 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 - correct answersNever 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 - correct answersthere 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 - correct answersall 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 - correct answerswith 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 - correct answersthe 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 - correct answersred lights Which type of truck-trailer combination has the greatest chance of a "crack-the-whip" rollover? 1. A tractor pulling three trailers