Class 1 Practice

Results

#1. How can the trailer hand valve be used?

To test the brakes after coupling

To apply the spring brakes

To lower the trailer's landing gear

To stop the trailer at stop lights

The trailer hand valve (also known as a spike, a trolley valve or a Johnson bar) controls only the trailer service brakes, not the tractor service brakes. After you have coupled your tractor to a trailer, you can use the hand valve to test the trailer service brakes independently of the tractor service brakes.