Inspecting Doubles/Triples Combinations
Inspecting Doubles/Triples Combinations
The pre-trip inspection for a multi-trailer combination adds articulation points, dolly hardware, and more air and electrical connections. The examiner expects a systematic walk-around and a coupling check that proves each connection.
What to inspect
- Tractor: fifth wheel, kingpin, jaws, mounting bolts, air lines, electrical cord, lights, tires, brakes.
- First trailer: landing gear, frame, doors, lights, reflective tape, mud flaps, brake adjustment.
- Converter dolly: pintle hook, latch, safety chains, fifth wheel, tires, rims, lights, air lines.
- Second/third trailer: kingpin, landing gear, lights, brakes, tires, load securement.
- Air system: build pressure, check for leaks, test tractor protection valve, test trailer spring brakes.
Coupling inspection
After each connection, perform a tug test and a visual check. Pull gently against the trailer with the trailer brakes set; the tractor should not move. Confirm the fifth-wheel release handle is in the locked position and the safety latch is engaged.
Worked example
A driver completes a walk-around but misses a chafed air line on the dolly. During the trip the line rubs through and the emergency line loses pressure, setting the trailer spring brakes. The inspection should have included flexing the lines and checking for rub points near the pintle.
Traps
- Inspecting only the tractor and first trailer.
- Skipping the dolly because it is "just a converter."
- Failing to check the load securement on the rear trailer.
- Not testing the breakaway system.