-
1. When
coupling a tractor to a semi trailer and you are backed up to
but not under the semi, you should:
a. Connect the air lines before proceeding.
b. Connect the electrical lines
c. Do nothing; continue to back under the semi trailer.
d. Grease the landing gear.
2. What
should you do when backing under a trailer?
a. Line up directly in front of the trailer.
b. Approach from about 30 degrees and turn before the 5th wheel
makes contact with the king pin.
c. Don't stop before backing under the trailer, but go slow.
d. Make sure the placards are correct for the cargo being hauled.
3. What
following thing should you do when operating a combination vehicle?
a. Drive at lower than posted speed limits.
b. Steer gently, brake early and prevent trailer skids.
c. Always drive with your low beam lights on.
d. Stop to assist disabled motorists.
4. What
can you do to help avoid rollover type accidents?
a. Reduce the air pressure in the trailer tires.
b. Move the fifth wheel to the far forward position.
c. Keep your load centered.
d. Use the shoulder of the road when making turns.
5. You
should use the trailer hand valve (trolly valve, johnson bar)
when:
a. Stopping.
b. To correct a trailer that is starting to jack knife.
c. To test the trailer brakes.
d. All of the above.
6. If
the air pressure is low, the tractor protection valve will close
and the following will happen:
a. The tractor and the trailer brakes will be applied automatically.
b. The trailer emergency brakes will be applied automatically.
c. Nothing.
d. The dual system will take over the braking operation.
7. If
you are pulling an older trailer and cross the air line hookups,
what will happen?
a. Nothing; the service and emergency lines are interchangeable.
b. The brakes on the trailer will not work.
c. The spring brakes will be activated.
d. The air in the service system will be emptied.
8. What
is the proper procedure to park trailers that do not have spring
brakes?
a. When you disconnect the air lines from the trailer, the brakes
are locked so there is nothing else that has to be done.
b. Turn the trailer valve to the "off" position before the air
pressure leaks off.
c. Use a cross-connector line to connect the service and emergency
brake system of the trailer. This will keep pressure on the brakes
and act as a parking brake.
d. Chock the wheels.
9. After
coupling, when the full weight of the trailer is resting on the
tractor, you should check for enough clearance between the rear
of the tractor frame and the landing gear and:
a. Clearance between the top of the tractor tires and the nose
of the trailer.
b. Clearance between the duals on the trailer.
c. Clearance between the air tanks and the safety relief valve.
d. Air pressure in all the tires.
10. When
raising the landing gear after coupling, how far up should the
gear be raised?
a. At least as high as the lowest part of the tractor mud flap.
b. At least 6 inches from the ground.
c. Until the upper limit of the gear is reached.
d. Until the gear goes in to low range.
11. When
uncoupling a semi trailer from a tractor, it is easier to release
the fifth wheel jaws if:
a. The jaws are well greased.
b. The tractor is backed up after setting the trailer parking
brakes.
c. The weather is dry.
d. An automatic 5th wheel release valve is installed.
12. What
additional items should you inspect when inspecting a combination
vehicle?
a. The fifth wheel and trailer landing gear.
b. The headlights.
c. The brake lights of the tractor.
d. The air compressor governor.
13. How
much space is required between the upper and lower plates on the
fifth wheel when coupled to a semi trailer?
a. One inch.
b. No space.
c. Approximately 1/2 inch.
d. There is no requirement.
14. Why
is it recommended to attach the glad hands together or to dummy
couplings when not coupled to a trailer?
a. It is a DOT regulation.
b. It is not recommended to do this.
c. To keep dirt and water out of the air system.
d. So air does not leak from the system.
15. What
color is the emergency air line on a combination vehicle?
a. Green
b. Blue
c. Yellow
d. Red
16. What
is the best way to recognize that a trailer skid is happening?
a. You will hear the tires skidding.
b. You will slow down.
c. You will see it in your mirrors.
d. The air pressure will drop.
17. What
is the best way to recover from a jack knife?
a. Use the trolley valve in conjunction with the foot pedal.
b. Stop applying the brakes.
c. Down shift.
d. Accelerate rapidly.
18. When
making a right turn:
a. Swing wide to the left before starting the turn.
b. Swing wide after starting the turn and keep the rear wheels
of the trailer as close to the curb without running over the curb.
c. Turn from the extreme right lane in to the extreme right lane
even if you have to go over the curb.
d. Swing wide to the right before starting the turn.
19. When
a vehicle goes around a corner, the rear wheels follow a different
path than the front wheels. This is called:
a. Lane-skipping.
b. Serpentine.
c. Off-tracking.
d. Short-tracking.
20. Which
of the following is not a true statement regarding the trailer
air supply control?
a. It is sometimes called the trolley valve or johnson bar.
b. It is used to control the tractor protection valve.
c. It is usually a red 8-sided knob.
d. If the air pressure drops into the range of 20-45 psi, the
tractor protection valve will close.
21. A
vehicle defect found during an inspection could help you avoid:
a. A costly breakdown on the road
b. A crash
c. An "out of service" violation
d. All the above
22. More
than half of truck driver deaths in crashes are the result of:
a. Alcohol
b. Drugs
c. Rollovers
d. Intersection accidents
23. Drivers
of combination vehicles need additional skill because:
a. Combination vehicles are longer
b. Combination vehicles are heavier
c. Combination vehicles have a complicated shifting pattern
d. "a" and "b" are correct
24. When
the wheels of a trailer lock up and the trailer swings around,
this is called:
a. Jackrabbit
b. Jacknife
c. Jack of all trades
d. Jackal
25. Relay
valves:
a. Signal the low air warning device
b. Reduce air pressure to the drive axle
c. Allow the trailer brakes to be applied more quickly
d. Are not required on combination vehicles
Safety & Compliance > CDL
"Combination Vehicles" Practice Test