What does the term “jackknife” refer to in relation to large vehicles?

The term “jackknife” in relation to large vehicles specifically refers to a dangerous situation where the trailer swings out and folds against the towing vehicle in a way that resembles a folding jackknife. This typically occurs when the angle between the tractor (the front part of the vehicle) and the trailer becomes too acute, often as a result of sudden braking or sharp turns. In this situation, the trailer may swing to the side, creating a risk of loss of control, potential collision, or rollover.

Understanding this concept is crucial for drivers of large vehicles, especially because it emphasizes the importance of maintaining proper control during maneuvers and being aware of how trailer sway can develop. Proper training and cautious driving can help prevent jackknifing incidents, which serve as critical safety concerns on the road.