If a trailer begins to jackknife, the driver:
Answers
Should not apply the trailer hand brake.
Should firmly apply the brakes.
Can straighten the trailer with the parking brake.
The Correct Answer and Explanation is :
The correct answer is: Should not apply the trailer hand brake.
When a trailer begins to jackknife, the driver’s primary concern should be regaining control of the vehicle to prevent further skidding or damage. A jackknife occurs when the trailer swings out at an angle to the towing vehicle, often caused by sudden braking or slippery road conditions. Here’s why the correct response is not to apply the trailer hand brake:
- Why not use the trailer hand brake?
Applying the trailer hand brake can worsen the situation by causing the trailer to lock up, which may increase the risk of a jackknife. The hand brake, when engaged during a skid, might cause the trailer wheels to stop moving while the tractor still slides forward. This can make it more difficult to regain control of the vehicle and may increase the angle of the jackknife. - What should the driver do?
Instead, the driver should try to gently apply the brakes to avoid sudden, harsh braking that could further upset the vehicle’s balance. If the vehicle is equipped with an anti-lock braking system (ABS), the driver should apply firm and steady pressure to the brake pedal, allowing the ABS to control wheel lock-up. In vehicles without ABS, the driver should “pump” the brakes, meaning applying and releasing them in quick succession to prevent wheel lockup. - Straightening the trailer:
If the trailer begins to jackknife, the driver should focus on steering the truck in the direction of the skid to straighten the rig. The parking brake should not be used for this purpose, as it is designed for securing the vehicle when stationary, not for controlling a skid. - Prevention:
The key to preventing a jackknife is smooth, gradual braking and maintaining a safe speed. Ensuring proper load distribution and being cautious in adverse weather conditions also reduces the likelihood of this dangerous situation.
By understanding how to react properly, the driver can regain control and prevent further damage or accidents during a jackknife scenario.