Simply put, it is any vehicle that is towing a trailer where the driver loses control (for a variety of reasons) and the trailer moves at a faster speed than the truck cab that is towing it. This causes the trailer to “fold” toward the towing vehicle –through an uncontrollable skid – which causes the cab to “fold” backward into the trailer. The most serious injury-related jackknife accident occurs with large semis (18+ wheelers) because of their tremendous size and weight.
What causes an 18-wheeler truck/trailer to jackknife?
There are a variety of reasons for jackknife truck accidents. But generally, they happen when a truck's drive train wheels (the four sets of double wheels at the rear of the cab) lock because the driver suddenly tries to stop. This causes the driver to lose control and the trailer – traveling at a faster speed – “yaws” forward, bringing the cab to the same side that the trailer is moving.
Like cars, trucks must slow down when roads are wet or covered with ice or snow; as skidding is a heightened danger. Windy conditions can also affect semis; especially those pulling high-profile trailers. Tandem trailers (a cab pulling two trailers) are especially susceptible to skids that can cause a serious jackknife accident.
Speeding and Sudden Stops
A truck topping a hill on an Interstate at 75 miles an hour that suddenly encounters an accident backup forces the driver to slam on the brakes. Only the most experienced drivers can do this safely; if they have enough distance to stop. Otherwise, the trailer’s speed is too high; especially if the brakes on the trailer might be in need of servicing.
Generally, a truck driver has three “sudden stop” options.
- Lock the steering axle brakes; that keep the rig moving in a straight-ahead direction; regardless of which direction the driver is steering.
- Secure the drive shafts; which should only be done at very slow speeds (and used when the truck is backing up). This is how a lot of jackknife accidents occur.
- Lock the trailer axles (or both if the rig is a tandem). But the driver loses directional control and can go into an uncontrollable skid; causing the semi to either jackknife or overturn.
Sometimes as the truck just begins to skid, the driver will overcorrect (either steering too much into the skid or in the opposite direction).
Sometimes a truck is dangerously overloaded, which places greater strain on the trailer axle’s braking system. This is especially dangerous if the trailer’s brakes need servicing.
If the cargo is not properly secured it can shift. This effect’s the trailer’s balance so badly it could tilt or move; often causing a jackknife accident.
Jason R. Schultz fights for injured motorists’ rights when a negligent truck driver causes harm. Contact our office today: (404) 474-0804.