The trailer hand valve should be used: Question The trailer hand valve should be used: Answers To test the trailer brakes. To check the connection between the trailer and tractor. To accelerate. To test the lights on the trailer. Explanation The trailer hand valve, also called the trolley valve or Johnson bar, is used to work the trailer brakes. It should be used only to test the brakes. This questions appears in the following tests: Colorado Combination Connecticut Combination Indiana Tank Indiana Combination Kansas Combination Maryland Double Mississippi Combination New Hampshire Combination North Carolina Combination North Dakota Double North Dakota Combination Texas Combination
