2024 CO CDL Practice Test: Double and Triples - Test 5 Based on 2024 CO CDL Handbook 16. Shut-off valves are sometimes called ______. A Johnson bar. B Cut-out cocks. C The closer lever. D Trolley valve. Next More 16/29 Progress 0 Errors Restart Next Next Double and Triples - Test 5 Back to Test List Double and Triples - Test 4 Tank - Test Challenge Library 12 More CO CDL Practice Tests 29 Tank - Test 30 Tank - Test 2 31 Tank - Test 3 32 Tank - Test 4 33 Tank - Test 5 34 Air Brakes - Test 35 All - Test 36 All - Test 2 37 All - Test 3 38 Tank and Hazmat - Test