Final answer:
The trailer hand valve should never be used for parking because it can damage the trailer brakes, cause the trailer to roll away, and lead to a loss of air pressure.
Step-by-step explanation:
Physics - High School
The trailer hand valve should never be used for parking for several reasons:
- It can cause damage to the trailer brakes: The trailer hand valve is designed for controlling the brakes while the vehicle is in motion. When used for parking, it can apply excessive force to the brakes, leading to damage or accelerated wear.
- It can cause the trailer to roll away: The trailer hand valve is not designed to act as a parking brake. If used for parking, there is a risk that the valve might not hold the trailer in place, causing it to roll away unsafely.
- It can lead to a loss of air pressure: The trailer hand valve controls the air pressure in the trailer's braking system. Using it for parking can result in a gradual loss of air pressure, compromising the effectiveness of the brakes.