COMBINATION PRACTICE TEST - PA CDL

11. "Bobtail" tractors are:
heavily loaded trailers.
tractors with two trailers.
tractors with a tank.
tractors without semitrailers.
12. When approaching a vehicle with a distracted driver, you should:
sound your horn.
maintain your safe following distance.
quickly pass the vehicle.
change lanes quickly.
13. If a worker is close to the roadway in a work zone, you should:
drive at the posted speed limit.
reduce your speed below the posted speed limit.
drive on the shoulder.
pull off the road and stop.
14. Before connecting the converter dolly to the rear trailer, make sure that:
the trailer height is slightly lower than the center of the fifth-wheel.
the shut-off valves at the rear of the first trailer are open.
the locking jaws rest on the kingpin.
the kingpin rests on the fifth-wheel.
15. When you make a quick lane change, the crack-the-whip effect can turn the trailer over. The crack-the-whip effect is caused by:
worn tire tread.
rearward amplification.
strong wind.
the rear trailer of a triple.
16. If your vehicle is equipped with air brakes, loss of air pressure in the emergency line will cause:
the trailer supply valve to open.
the trailer emergency brakes to come on.
the vehicle to slide back and forth.
the springs to put on the brakes.
17. The heavier the vehicle:
the higher the center of gravity will be.
the more work the brakes must do to stop it.
the less work the brakes must do to stop it.
None of the above.
18. What is the proper following distance for a 50 foot truck traveling at 50 mph?
5 seconds
6 seconds
10 seconds
25 seconds
19. Having ABS on only the trailer:
still gives you more control over your vehicle during braking.
is very dangerous.
makes the trailer more likely to roll over.
makes the trailer more likely to swing out.
20. Most heavy-duty vehicles use:
hydraulic brakes.
air brakes.
solid brakes.
pressure brakes.
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