29. Which of these statements is true?

a. The brake and suspension systems of combination vehicles work best with a light load.
b. Always delay braking a heavy vehicle until you have no other choice.
c. Light vehicles need more braking power to stop than heavy ones.
d. "Bobtail" tractors can take longer to stop than a combination vehicle loaded to maximum gross weight.

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

a. tractor's air to dump into the trailer tank through the service line.
b. emergency trailer brakes to come on.
c. air compressor to unload instead of pumping air.
d. trailer supply valve to open.

31. Why should you be sure that the fifth wheel plate is greased as required?

a. To ensure good electrical connections.
b. To prevent steering problems.
c. To keep the brake system in balance.
d. To reduce heat and noise.

32. The front trailer supports are up and the trailer is resting on the tractor. Make sure:

a. there is enough clearance between the tops of the tractor tires and the nose of the trailer.
b. there is enough clearance between the tractor frame and the landing gear.
c. neither a nor b is correct.
d. both a and b are correct.

33. You have a major leak in the service line and you put on the brakes. service air pressure will escape and cause the:

a. trailer emergency brakes to come on.
b. trailer tank pressure to be lost.
c. tractor spring brakes to lock on.
d. trailer's tank pressure to go to the tractor's system.

34. The hand valve should be used:

a. only with the foot brake.
b. to test the trailer brakes.
c. as a parking brake.
d. only when the trailer is fully loaded.

35. The air leakage rate for a combination vehicle (engine off, brakes on) should be less than ___ psi per minute.

a. 1
b. 2
c. 3
d. 4

Answers: (29)d   (30)b   (31)b   (32)d   (33)a   (34)b   (35)d