CDL DOUBLES PRACTICE TEST PENNSYLVANIA

11. When checking the lights before driving:
the engine must be running.
make sure the parking brake is not set.
you should turn off the engine.
you should check them from inside the vehicle.
12. Hydroplaning:
can occur only if there is a lot of water on the road.
can occur at speeds as low as 30 mph.
is less likely if tire pressure is low.
can occur at speeds as low as 10 mph, if there is a lot of water.
13. When coupling double trailers, you can secure the second trailer by:
setting the trailer emergency brakes.
using the trailer spring brakes.
chocking the wheels.
All of the above.
14. When the trailer breaks away or develops a bad leak, the tractor protection valve will close automatically and:
the trailer emergency brakes will come on.
the engine will shut down.
the trailer supply valve will stay open.
the tractor will lose all air pressure.
15. Air brakes use ________ to make the brakes work.
compressed air
compressed gases
compressed gas cylinders
compressed oil
16. In vehicles with air brakes, the two markings on a front brake limiting valve are:
high and low.
normal and slippery.
left and right.
wet and dry.
17. You should always try to back toward the driver's side because:
backing toward the left side is more dangerous.
you can watch the rear of your vehicle out the side window.
you can more easily correct any steering errors.
None of the above.
18. If driving a heavy vehicle, you should:
stay in the right lane.
try to pass other vehicles going uphill.
stay in the left lane.
avoid braking.
19. If you are carrying a heavy load that is slowing you down, you should:
drive in the left lane.
drive in the right lane.
drive on the shoulder.
keep the vehicle in third gear.
20. In vehicles with air brakes, the air compressor governor:
controls how much air the air compressor will pump into the air storage tanks.
controls when the air compressor will pump air into the air storage tanks.
controls when the air storage tanks will pump air into the air compressor.
None of the above.
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