Combination Test - Texas CDL Practice Questions with Answers

In coupling, just before the tractor is coupled with the trailer you should: connect the emergency and service air lines. In coupling, you should not move the tractor after it is coupled until you push in the air supply knob and: wait until the air pressure is normal. What happens immediately if the service air line comes apart while driving, but the emergency line is okay? Nothing is likely to happen until you press the brakes. In coupling, before you back under the trailer, how do you lock the trailer brakes? Pull out the yellow air supply knob. For the coupling to be complete, the safety catch for the fifth wheel locking lever must be: over the locking gear. What is the air leakage rate for a combination vehicle with the engine and brakes off? Less than 3 PSI per minute. What is the maximum air leakage rate for a combination vehicle with the engine off and the brakes on? 4 PSI per minute. A driver crosses the air lines when hooking up to an old trailer. What will happen? If the trailer has no spring brakes, he or she could drive away but wouldn't have trailer brakes. To unlock the fifth wheel, pull the release handle to the: open position. When driving a set of doubles, it is necessary to close the: back shut-off valve in the last trailer. You are coupling a semitrailer to your tractor but have not yet backed under. The trailer is at the right height when: it will be raised slightly when the tractor is backed under it. Air and electric lines from the tractor to the trailer should be: secured, but with enough slack for turns.