The right side steering column is used to test trailer brakes only and is not used in motion. What is this device called?

• A. Johnson Bar
• B. Steering Column Test
• C. Trailer Brake Lever
• D. King Pin

Answer: (A)

The Johnson Bar is the lever you find on the right side of the steering column that allows you to apply the trailer brake system while the vehicle is stationary. Using it lets you test that the trailer brakes engage properly, that the air lines and valves function, and that the brakes respond without needing to move the tractor. It’s specifically for testing during inspections or maintenance, not for use while driving. The other terms don’t describe this testing device—the king pin is the hitch connection, and the other names aren’t the standard term for the steering-column control used to test trailer brakes.