Skid Control and Emergency Procedures
Why multi-trailer rigs skid
A skid happens when tires lose traction - from braking too hard, steering too sharply, or driving too fast for conditions. In a multi-trailer combination, a skid in one unit can pull the others out of line, producing a jackknife or a trailer swing. The rear trailer is the most vulnerable because of rearward amplification.
Concepts to name
- Jackknife: the tractor and trailer fold toward each other; usually caused by locking the tractor drive wheels.
- Trailer swing: the rear of a trailer swings out sideways; common on slippery roads.
- Brake-induced skid: locking wheels by braking too hard; release and reapply.
- Steering-induced skid: turning too sharply for the speed; ease off the steering.
- Recovery: release the brakes to let the wheels roll, steer in the direction you want to go, and do not overcorrect.
Common traps
A frequent trick is the idea that you should brake harder to recover from a skid - releasing the brakes is correct. Another is the belief that a heavier combination cannot jackknife. A third is assuming ABS prevents all skids; it helps but does not eliminate them.
Rule of thumb
If the rear trailer starts to swing, ease off the accelerator and steer gently in the direction of the skid - do not brake hard and do not overcorrect.