Final answer:
Using the hand valve before stepping on the brake pedal is not effective in preventing a jackknife in normal driving. It is important to use proper braking techniques to prevent a jackknife.
Step-by-step explanation:
The statement is False. Using the hand valve before stepping on the brake pedal is not effective in preventing a jackknife in normal driving.
The hand valve, also known as the trailer brake control, is used to control the brakes of a trailer connected to a vehicle. It allows the driver to manually apply the trailer brakes independently of the vehicle brakes.
A jackknife is a dangerous situation where the trailer swings out to the side, forming a V shape with the vehicle. It usually occurs when the trailer's wheels lock up and skid, causing the trailer to lose traction and slide sideways.
To prevent a jackknife, it is important to use proper braking techniques. Applying too much force to the trailer brakes can actually make the situation worse and increase the risk of a jackknife. It is recommended to apply smooth and gradual braking through the vehicle's brake pedal rather than relying solely on the hand valve.