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7.3 – Inspecting Doubles and Triples

Use the seven-step inspection procedure described in Section 2 to inspect your combination vehicle. There are more things to inspect on a combination vehicle than on a single vehicle. Many of these items are simply more of what you would find on a single vehicle. (For example, tires, wheels, lights, reflectors, etc.) However, there are also some new items to check. These are discussed below.

7.3.1 – Additional Checks

Perform these checks in addition to those already listed in "Section 2, Step 5: Do Walk-around Inspection."

Check fifth wheel (lower).

  • Securely mounted to frame.
  • No missing or damaged parts.
  • Enough grease.
  • No visible space between upper and lower fifth wheel.
  • Locking jaws around the shank, not the head of kingpin.
  • Release arm properly seated and safety latch/lock engaged.

Check fifth wheel (upper).

  • Glide plate securely mounted to trailer frame.
  • Kingpin not damaged.

Air and electric lines to trailer.

  • Electrical cord firmly plugged in and secured.
  • Air lines properly connected to glad hands, no air leaks, properly secured with enough slack for turns.
  • All lines free from damage.

Sliding fifth wheel.

  • Slide not damaged or parts missing.
  • Properly greased.
  • All locking pins present and locked in place.
  • If air powered, no air leaks.
  • Check that fifth wheel is not so far forward that the tractor frame will hit landing gear or cab will hit the trailer, during turns.

Landing Gear

  • Fully raised, no missing parts, not bent or otherwise damaged.
  • Crank handle in place and secured.
  • If power operated, no air or hydraulic leaks.

Double and Triple Trailers

  • Shut-off valves (at rear of trailers, in service and emergency lines).
    • Rear of front trailers: OPEN.
    • Rear of last trailer: CLOSED.
    • Converter dolly air tank drain valve: CLOSED.
  • Be sure air lines are supported and glad hands are properly connected.
  • If spare tire is carried on converter gear (dolly), make sure it is secured.
  • Be sure pintle-eye of dolly is in place in pintle hook of trailer(s).
  • Make sure pintle hook is latched.
  • Safety chains should be secured to trailer(s).
  • Be sure light cords are firmly in sockets on trailers.

Multiple-Choice Questions:

Question #351 (1 of 1)

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When inspecting doubles or triples, in what position should the air shut-off valves be in?

  • Air valves should be open on all trailers
  • Rear of front trailers: open, rear of last trailer: closed
  • Rear of front trailers: closed, rear of last trailer: open
  • Air valves should be closed on all trailers

Shut-off valves (at rear of trailers, in service and emergency lines):

  • Rear of front trailers: OPEN.
  • Rear of last trailer: CLOSED.
  • Converter dolly air tank drain valve: CLOSED.

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