Driving SafelyQuestion 57 of 60
Why should you generally avoid using the trailer hand valve (trolley/spike valve) to control the vehicle in normal driving?
a.Applying only the trailer brakes can cause the trailer to skid and jackknife
b.It turns off the headlights
c.It raises the landing gear
d.It disconnects the air lines
Explanation
Using the trailer hand valve alone applies only the trailer brakes, which can lock the trailer wheels and cause a skid or jackknife, especially on slippery roads. Normal braking should use the foot brake, which applies brakes on all wheels together. The hand valve is not a substitute for the service brakes.
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