Why should the trailer hand valve (trolley valve) NOT be used for parking?
a.It uses too much air
b.Air can leak away and release the brakes, allowing the trailer to move
c.It damages the brake drums
d.It is illegal in all states
Explanation
The trailer hand valve should never be used for parking because air can leak away over time. If the air leaks out, the brakes will release and the trailer could move. Always use the parking brakes for parking.