Combination Test 1 2025

When should you use the hand valve to park a combination vehicle?

• To park at loading docks

• To park on a grade

• Never

Which answer is correct for the air valves when testing the trailer service brakes only?

• Service Brake: off; Parking Brake: off; Trailer air supply: in / open; Trolley: applied

• Service Brake: off; Parking Brake: off; Trailer air supply: in / open; Trolley: released

• Service Brake: off; Parking Brake: off; Trailer air supply: out; Trolley: applied

• No answers are correct

You are coupling a semi-trailer to your tractor but have not yet backed under. The trailer is at the right height when:

• The kingpin is about 1 1/4 inches above the fifth wheel

• The end of the kingpin is even with the top of the fifth wheel

• The trailer will be raised slightly when the tractor is backed under it

How should you test the tractor trailer connection for security?

• Put the tractor in gear and pull ahead with a sharp jerk

• Pull gently forward in low gear against the locked trailer brakes, then inspect the coupling

• Rock the trailer back and forth with the trailer brakes locked

Which answer is correct for the air valves when testing the trailer spring / parking brakes only?

• Service Brake: off; Parking Brake: off; Trailer air supply: in / open; Trolley: released

• Service Brake: off; Parking Brake: off; Trailer air supply: out; Trolley: released

• Service Brake: off; Parking Brake: off; Trailer air supply: out; Trolley: applied

• No answers are correct

Your emergency air line breaks or gets pulled apart while you are driving. The loss of pressure will cause the:

• Emergency trailer brakes to come on

• Air compressor to unload instead of pumping air

• Trailer supply valve will open

• Nothing will happen until air pressure reaches 10 PSI

You supply air to the trailer tanks by:

• Pushing in the trailer air supply valve

• Pulling out the trailer air supply valve

• Connecting the service line glad hand

• Pulling out the system parking brake

There are two things that a driver can do to prevent a roll over. They are: (1) keep the cargo as close to the ground as possible; and (2):

• Make sure that the brakes are properly adjusted

• Go slowly around turns

• Keep the fifth wheel's free play as tight as possible

You are coupling a semi-trailer to your tractor but have not yet backed under. The trailer is at the right height when:

• The kingpin is about 1 1/4 inches above the fifth wheel

• The end of the kingpin is even with the top of the fifth wheel

• The trailer will be raised slightly when the tractor is backed under it

The fifth wheel locking lever is not locked after the jaws close around the kingpin; this means:

• You can set the fifth wheel for weight balance

• The parking lock is off, and you may drive away

• The coupling is not right and should be fixed before driving the coupled unit