Landing Gear Fundamentals and Service

Question 1

1. Fifth wheel couplings are used to connect a semi-trailer to:
   a) a tractor.
   b) a converter dolly.
   c) the lead trailer of a B train combination.
   d) all of the above are correct.

Answer 1

1. d) all of the above are correct.

Question 2

2. The fifth wheel component that provides the bearing surface for the weight of the
front of the semi-trailer is the:
a) top plate.
b) coupling jaws.
c) mounting bracket.
d) bracket pins and bushings.

Answer 2

a) top plate.

Question 3

3. The purpose of the coupling jaws in a fifth wheel is to engage and secure the trailer
   kingpin.
   a) true
   b) false

Answer 3

a) true

Question 4

4. Fifth wheel assemblies are rated based on four ( 4) considerations. What are they?
a)
b)
c)
d)

Answer 4

a) towed vehicle weight (TVW)
b) maximum expected draw bar load
c) vertical load to be carried by the fifth wheel
d) type of operation

Question 5

5. Four ( 4) advantages of sliding over stationary fifth wheels are:
a)
b)
c)
d)

Answer 5

a) Weight can be transferred between tractor axles.
b) Trailers with different kingpin settings can be accommodated.
c) Vehicle length can be varied.
d) Additional maneuverability can be gained.

Question 6

6. Which of the following fifth wheels is the most commonly used fifth wheel?
   a) rigid or no-tilt type.
   b) semi-oscillating type.
   c) fully oscillating type.
   d) compensating type.

Answer 6

b) semi-oscillating type.

Question 7

7. Pintle hooks designed to remove the clearance between the hook and the drawbar eye
   are called

Answer 7

Pintle hooks designed to remove the clearance between the hook and the draw bar eye
are called no-slack pintle hooks.

Question 8

8. The function of the safety restraint on a trailer unit coupled with a pintle hitch is to

Answer 8

The function of the safety restraint on a trailer unit coupled with a pintle hitch is to
ensure that the trailer remains attached to the towing unit in the event of a trailer
hitch separation.

Question 9

9. List four ( 4) faults that can be identified by visually inspecting a fifth wheel.
a)
b)
c)
d)

Answer 9

Any four ( 4) of the following are correct.

a) cracked, bent, broken or damaged components
b) missing parts
c) loose or missing fasteners
d) condition of locking devices such as cotter pins
e) top plate wear or warpage
f) rusting or corrosion

Question 10

10. Excessive clearance between the fifth wheel jaws and the lock tester kingpin is a
    result of:
    a)
    b)

Answer 10

a) improper jaw adjustment and/or

b) excessive jaw wear.

Question 11

11. The amount of wear in fifth wheel oscillating pins and bushings can be checked by:
    a) barring the slide bracket back and forth.
    b) barring the top plate up and down as well as back and forth.
    c) barring the lockjaws back and forth.
    d) using the lock tester

Answer 11

b) barring the top plate up and down as well as back and forth.

Question 12

12. A distorted or cracked fifth wheel top plate must be straightened or welded before it
    can be rebuilt.
    a) true
    b) false

Answer 12

b) false; A top plate must not be welded or straightened because it will weaken.

Question 13

13. The contact surface of the fifth wheel top plate is lubricated with:
    a) gear oil.
    b) engine oil.
    c) extreme pressure grease.
    d) water resistant lithium-based grease.

Answer 13

d) water resistant lithium-based grease.

Question 14

14. What two (2) fifth wheel components should be lubricated with a light lubricating
    oil?
    a)
    b)

Answer 14

a) cam track path and pivot point

b) rack and slide path on sliding fifth wheels

Question 15

15. A trailer kingpin must be replaced if it is bent more than 1 degree.
    a) true
    b) false

Answer 15

a) true

Question 16

16. A trailer kingpin must be replaced if its diameter is worn more than:
    a) 3 mm (0.125 in).
    b) 6 mm (0.250 in).
    c) 12 mm (0.500 in).
    d) 16 mm (0.625 in).

Answer 16

a) 3 mm(0.125 in)

Question 17

17. Before backing a tractor into a semi-trailer, you must:
    a) inspect the fifth wheel for damage.
    b) ensure that slider plungers are engaged.
    c) check that the lockjaws are open.
    d) all of the above are correct.

Answer 17

d) all of the above are correct.

Question 18

18. Trailer air and electrical connections can be made after the trailer is securely coupled
    to the fifth wheel.
    a) true
    b) false

Answer 18

b) false; Trailer connections must be done before coupling in order to set the
trailer brakes

Question 19

19. What test must be performed after the trailer is coupled to the fifth wheel?

Answer 19

A pull test must be performed by gently pulling against the trailer parking brakes.

Question 20

20. The first step in uncoupling a tractor/semi-trailer combination is to:
    a) set the trailer brakes.
    b) set the tractor brakes.
    c) position the unit on firm, level ground.
    d) block the tractor wheels.

Answer 20

c) position the unit on firm, level ground.

Question 21

21. When operating the landing gear to disconnect a semi-trailer, use high speed until the
    skid pads contact the ground and then shift to low speed for 4 to 8 additional turns.
    a) true
    b) false

Answer 21

. a) true