Skid Recovery, Jackknifing, and Emergency Procedures
Skid and emergency questions test recognition and the first correct action. The exam wants you to identify which wheels are skidding, release the cause, and steer without making the jackknife worse.
Skid recovery
- Rear-wheel skid: ease off the accelerator and steer in the direction the rear is sliding. Do not stab the brakes. As traction returns, straighten the wheel.
- Front-wheel skid: release the brake to restore steering, then steer where you want to go.
- Tractor jackknife: drive wheels lock and the tractor rear swings out. Trailer jackknife: trailer wheels lock and the trailer swings. In both, release the brake to let the wheels roll and steer to regain alignment.
- With ABS, brake and steer; do not pump the pedal.
Emergency procedures
- Brake failure: downshift, apply the parking/emergency brake gradually, and use a runaway ramp if available.
- Tire blowout: hold the wheel firmly, ease off the accelerator, avoid hard braking, and slow to a stop.
- Off-road recovery: slow before returning to the pavement; a hard steer-back can roll the combination.
Worked example: On wet pavement, a driver brakes hard and the trailer wheels lock; the trailer swings left. Reasoning: locked trailer wheels have lost lateral grip, so the trailer rotates around the tractor. The correct first move is to release the brake so the trailer wheels roll, then steer to follow the trailer and straighten out. Holding the brake or steering right would deepen the jackknife.
Traps
- Steering away from a rear-wheel skid.
- Pumping ABS brakes.
- Using the trailer hand valve in an emergency stop.
- Overcorrecting after a blowout.