11 M.6 Combination Vehicles

11M.6.1 Combination Vehicles Only

Air and Electric Lines and / or Connectors

Description:

Carry air and electricity from power unit to trailer.

Why Inspect:
Air Brakes

Loss of air to the trailer will result in a partial or total loss of braking to the towed unit. A low air condition will cause sudden application of the trailer's spring brakes, which may result in loss of control and lead to a crash.

Electric Brakes

Loss of electrical connection to the trailer will result in total loss of braking and control to the towed unit and can lead to a crash.

Electric Lines

Damaged lines may result in loss of the vehicle's ability to communicate its maneuvers to other drivers (no turn, or brake lights). Not being seen by other traffic at night is a serious traffic hazard and can lead to a crash.

Inspection:
  • Inspect that air and electric connectors on the power unit and trailer are seated and sealed, free of damage and locked into place.
  • Inspect that air hoses and electrical lines are not cut, cracked, chafed, spliced, taped or worn (steel braid and / or electrical conductor must not show through). Listen for air leaks (air brake systems only).
  • Inspect that electrical lines and air lines (if equipped) are not tangled, crimped or pinched, or dragging against vehicle parts or the ground.

Note: You must inspect the connections on both the power unit and trailer to receive credit.

For the remainder of this section (11 M.6.1), you will need to study the type of coupling system your vehicle is equipped with - that you will be using for your Vehicle Inspection test:

  • Fifth Wheel Combination, or
  • Pintle Hook Combination, or
  • All Other Types of Combinations.

For Fifth Wheel Skid Plate

Fifth Wheel Skid Plate

Description:

Plate on which the trailer rests and secures the trailer kingpin.

Why Inspect:

A faulty or damaged fifth wheel skid plate and an improper connection between the tractor and the trailer can result in handling problems, rollover, or separation of the tractor and trailer leading to a crash.

Inspection:
  • Inspect that the fifth wheel skid plate is securely mounted to the vehicle by the fifth wheel platform.
  • Inspect for cracks, breaks or excessive wear.
  • Inspect for proper lubrication, if applicable.

Kingpin, Apron & Gap

Description:

Pin that attaches the semi-trailer to tractor (kingpin) and the metal plate attached to the kingpin that provides the surface for resting the trailer on the fifth wheel (apron).

Why Inspect:

Wear or damage to the kingpin can result in handling problems, rollover, or separation of the tractor and trailer leading to a crash.

Inspection:
  • Inspect that the kingpin is in place and not bent, damaged or worn.
  • Inspect that the visible part of the apron is not bent, cracked, or broken.
  • Inspect that the trailer is lying flat on the fifth wheel skid plate and there is no space between the apron and fifth wheel (no gap).
  • Inspect for proper lubrication, if applicable.

OR

For Pintle Hook Combinations Only

Pintle Hook

Description:

Tow hitch or receiving coupling which the trailer drawbar ring and / or eye locks into.

Why Inspect:

A faulty or damaged pintle hook and an improper connection between the power unit and the trailer can result in handling problems, rollover, or separation of the power unit and trailer leading to a crash.

Inspection:
  • Inspect that the pintle hook is securely mounted to the vehicle frame.
  • Inspect for loose or missing parts including mounting bolts, nuts, pins, brackets and clamps.
  • Inspect for cracks, breaks or excessive wear.

Trailer Drawbar Ring & Tongue

Description:

Trailer drawbar ring or eye attached to the front of the trailer tongue that secures into the pintle hook for coupling. The trailer tongue that extends from the trailer's main body frame to allow for coupling and turning.

Why Inspect:

Wear, damage, cracks or improper welds in the drawbar ring and trailer tongue may result in loss of the trailer leading to a crash.

Inspection:
  • Inspect that the drawbar ring or eye is not bent or twisted.
  • Inspect that the drawbar ring or eye is secured to the trailer tongue and there are no loose or missing bolts, broken welds, or cracks.
  • Inspect that the drawbar ring or eye is not worn.
  • Inspect the trailer tongue for dents, twists, cracks, and broken welds and that the trailer tongue can support the weight of the load. If extendable, inspect that bolts, locking pins and cotter pins are in place.

OR

All Other Types of Combinations

Note: Coupling systems vary. If you have another type of coupling system, you will need to describe to the examiner how it works and what you are inspecting.

Tow Hitch

Description:

Tow or receiver hitch and trailer ball, which the trailer coupler rests on.

Why Inspect:

A faulty or damaged tow hitch or other mechanism and an improper connection between the power unit and the trailer can result in handling problems, rollover, or separation of the power unit and trailer leading to a crash.

Inspection:
  • Inspect that the tow hitch or other mechanism is securely mounted to the vehicle frame. Inspect sway bar and / or control, if equipped.
  • Inspect for loose or missing parts including mounting bolts, nuts, pins, brackets and clamps, including the trailer ball or other mechanism.
  • Inspect for cracks, breaks or excessive wear.

Trailer Coupler & Tongue

Description:

Trailer coupler attached to the front of the trailer tongue that latches to the trailer hitch and trailer ball. The trailer tongue that extends from the trailer's main body frame to allow for coupling and turning.

Why Inspect:

Wear, damage, cracks or improper welds in the trailer coupler and trailer tongue may result in loss of the trailer, leading to a crash.

Inspection:
  • Inspect that the trailer coupler is not bent or twisted.
  • Inspect that the trailer coupler is secured to the trailer tongue and there are no loose or missing bolts, broken welds, or cracks.
  • Inspect that the trailer coupler is not worn.
  • Inspect the trailer tongue for dents, twists, cracks, and broken welds and that the trailer tongue can support the weight of the load. If extendable, inspect that bolts, locking pins and cotter pins are in place.

Locking and Safety Devices

Description:

Locking connection and safety devices that keep the trailer locked into place.

Why Inspect:

The trailer could uncouple during travel if the locking mechanisms are not secured. Safety devices help to keep the locking mechanism in place and provide assistance should the connection fail.

Inspection: Fifth Wheel Coupling Systems Only
  • Look into fifth wheel gap and inspect that locking jaws or lever are fully secured around the kingpin and inspect for play between kingpin and locking jaws and / or lever.
  • Inspect that the release arm is in the engaged position and the safety latch or lock (if equipped) is in place.
  • Inspect the sliding fifth wheel locking pins (if equipped) for damage and the pins are fully engaged.
OR
Inspection: All Other Coupling Systems
  • Inspect the locking mechanism or latch for missing or broken parts and make sure the pintle or hitch release lever or latch is locked in place and secure.
  • Inspect that safety pins and cotter pins are in place and not missing, if present.
  • Inspect that safety cables or chains are secure, crossed, and free of kinks and excessive slack, if present. Breakaway cables must be engaged.

11M.6.2 Trailers Only

Landing Gear & Clearance

Description:

Supports front end of trailer when trailer is not coupled to a truck or tractor.

Why Inspect:

Landing gear must be raised properly so that it will not strike the ground during travel and must clear the back of the power unit while turning. Its handle must be secured to the vehicle so it will not move and strike other traffic. Any damage to landing gear supports may result in the trailer tipping or falling over when disconnected.

Inspection:
  • Inspect that the landing gear is fully raised, has no missing parts, the crank handle is secure, and the support frame and landing pads are not damaged.
  • If power operated, inspect for air or hydraulic leaks.
  • If tractor semi-trailer, inspect that the fifth wheel is positioned properly so that the tractor frame will clear the landing gear during turns.

Reflective Tape

Description:

Reflective tape on the side and rear of the trailer, if required.

Why Inspect:

Reflective tape on a trailer allows the driver of a commercial vehicle to be seen and to communicate presence with other traffic.

Inspection:
  • Inspect that reflector tape on the sides and rear of the trailer are present and affixed securely to the vehicle.

Note: Reflective tape is only required for trailers.

Some jurisdictional laws may require for school buses.