1. Loss of Control: When you apply the trailer hand valve while driving, it actuates the brakes on the trailer only, not on the towing vehicle. This can cause an imbalance in the braking forces between the trailer and the towing vehicle, potentially leading to loss of control.
2. Jackknifing: Especially in slippery road conditions, activating the trailer hand valve suddenly while driving can cause the trailer to swing out and jackknife, resulting in a severe accident.
3. Increased Stopping Distance: Using the trailer hand valve may increase the overall stopping distance of the vehicle combination. Since only the trailer brakes are engaged, a significant portion of the braking power is lost, compromising the vehicle's ability to stop promptly.
4. Uneven Tire Wear: Applying the trailer hand valve frequently can cause uneven wear and tear on the trailer's tires, as they are subjected to more frequent and intense braking than the tires of the towing vehicle.
5. Mechanical Damage: Overusing the trailer hand valve can put excessive strain on the trailer's braking system, potentially causing mechanical damage to components such as brake drums, brake pads, and brake lines.
6. Misinterpretation of Braking: Other road users may be confused by the inconsistent braking behavior, particularly if the towing vehicle is not indicating or the brake lights are not synchronized with the trailer's brakes.
Therefore, it is generally advised not to use the trailer hand valve while driving and only engage it when the towing vehicle is stationary, such as when parked or in heavy traffic.
