Inspecting Trailer Sets and Airflow

Walk-Around Inspection for Multi-Trailer Combinations

Conducting a thorough pre-trip inspection on a combination vehicle requires using the seven-step inspection procedure described in Section 2 of the commercial driver manual. While the underlying routine follows the same disciplined structure you use for any commercial vehicle, a combination vehicle includes more inspection items than a single vehicle. Because you are pulling multiple units, everyday components like tires, wheels, lights, and reflectors are found in far greater quantities throughout your rig. Missing a single damaged wheel or a malfunctioning clearance light can compromise the safety of the entire combination.

When inspecting double and triple trailer sets, your walk-around inspections must be performed in addition to the standard air brake checks outlined in subsection 5.3. Walking down the length of the combination demands close attention to how the units are physically linked. Verify that each converter dolly’s pintle-eye is in the pintle hook of the trailer ahead of it and that the pintle hook is latched. Check that the dolly’s safety chains are secured to the trailer or trailers and that any spare tire carried on the converter gear is secured.

The physical connections between the trailers also carry the critical air and electrical pathways that control the rear units. During your walk-around, verify that glad hands are properly connected. All air-lines on double and triple trailers must be supported properly to avoid chafing, snagging, or dragging against vehicle framing. Finally, check that light cords are firmly plugged into the electrical sockets on the trailers so that lighting signals transfer reliably to every trailer in the set.