Generally speaking, jackknifes happen when the wheels of a vehicle lose traction. A big rig has two separate parts: a cab where the driver sits and operates the vehicle and a trailer that holds cargo. Due to the separated nature of these large vehicles, sometimes the trailer will swing out to one side of the cab, forming an “L” or “V” shape as it continues with forward momentum. Too many people assume that this only happens in winter when roads are icy and slick. However, this can happen during any season so it is crucial to know what elements can lead to a loss of traction.
Wheels can lose traction when they start skidding instead of rolling. Skidding happens when a trucker improperly brakes or enters a turn too quickly and the wheels lock, causing the back end of the truck to swing out. Loss of traction can also happen when the backs of trucks are empty, and therefore very light, or when the roads are wet.
In some cases, a trucker can recover from minor swings, but at a certain point, the back end of a truck swings so far outward and forward that there is no way to recover and the truck comes to a stop.