Skid Control and Emergencies
This domain tests recovery technique and emergency decision-making: what to do when traction is gone, when the brakes fail, or when a tire blows at highway speed. The exam favors the counterintuitive answer - usually, less braking and less steering input, not more.
Skid recovery
- Recognize the type: drive-wheel (rear) skid where the trailer pushes the tractor around, front-wheel skid where steering stops responding, or a braking skid on all wheels.
- In any skid, stop braking and stop accelerating to let the tires regain grip.
- Steer in the direction you want the front of the vehicle to go; in a rear-wheel skid, steer the way the rear is sliding. Do not overcorrect - small, smooth inputs.
- Look where you want to go, not at what you are about to hit.
- Use engine brakes cautiously on slick surfaces; they can start a drive-wheel skid.
Other emergencies
- Tire failure: hold the wheel firmly, keep off the brakes, and let the vehicle slow while steering straight ahead.
- Brake failure: downshift, apply the parking or emergency brake gradually, pump air pressure if you have it, and look for an escape ramp or a soft landing.
- Fire: stop, shut off the engine, get everyone out and away, then fight the fire from upwind only if it is small.
- ABS: brake firmly and steer. Do not pump the pedal.
Worked example
A tractor-trailer begins to skid on a wet ramp and the trailer swings to the left. Reasoning: the rear wheels have lost grip and the vehicle is rotating. The driver releases the brakes, steers right - the direction the rear is sliding - and holds a light, steady input without adding throttle. Adding brakes or steering harder would deepen the skid and risk a jackknife.
Traps
- Standing on the brakes during a skid; locked wheels cannot steer.
- Overcorrecting, which produces a skid in the other direction.
- Releasing the seat belt or bailing out of a moving vehicle.
- Pumping ABS brakes as if they were older air brakes.