Jackknifing is a common term we have all heard but do not necessarily know its meaning. Jackknifing is when the front cab and rear trailer of a semi-truck move out of sync from each other because the driver of the truck is forced to slam on the brakes.
Instead of the trailer riding safely behind the truck cab, it sways to the side and can eventually make the entire truck lose control.
When a trailer, particularly a full trailer, moves like this, the driver is unable to keep control. Think of a semi and trailer at a nearly 90-degree angle to each other… the full rig can be in the shape of a “V.” When this happens, there is no controlling the momentum and the truck jackknifes.