May 7, 2009 · "The trailer hand valve (also called the trolley valve or Johnson Bar) works the trailer brakes. The trailer hand valve should be used only to test the trailer brakes. Do not use it in driving because of the danger of making the trailer skid."

The trailer hand valve (also called the “trolley valve” or “Johnson bar”) works the trailer brakes. The trailer hand valve should be used only to test the trailer brakes. Do not use it in driving because of the danger of making the trailer skid.

6.2.1 – Trailer Hand Valve. The trailer hand valve (also called the trolley valve or Johnson bar) works the trailer brakes. The trailer hand valve should be used only to test the trailer brakes. Do not use it in driving because of the danger of making the trailer skid.

The trailer hand valve (also called the trolley valve or Johnson bar) works the trailer brakes. The trailer hand valve should be used only to test the trailer brakes. Do not use it in driving because of the danger of making the trailer skid. The foot brake sends air to all of the brakes on the vehicle (including the trailer(s)).

6.2.1 – Trailer Hand Valve. The trailer hand valve (also called the trolley valve or Johnson bar) works the trailer brakes. The trailer hand valve should be used only to test the trailer brakes. Do not use it in driving because of the danger of making the trailer skid.

"Glad hands" are coupling devices used to connect the service and emergency air lines from the truck or tractor to the trailer. The couplers have a rubber seal that prevents air from escaping. Clean the couplers and rubber seals before a connection is made.

Discover the parts of a combination vehicle braking system and how to use them safely. Learn about the trailer hand valve, tractor parking valve, and trailer air supply control.

The trailer hand valve works the trailer brakes. Which of these statements is true? a) The trailer hand valve should be used only to test the trailer brakes b) The foot brake sends air to all the brakes on the vehicles (including the trailer(s)).

Why should you NOT use the trailer hand valve while driving? The danger of making the trailer skid. Describe what the trailer air supply control does. Push in -- Supply air to trailer; Push out -- Shut air off and put on trailer emergency brakes. Describe what the service line is for.

Study with Quizlet and memorize flashcards containing terms like Why should you not use the trailer hand valve while driving?, Describe what the trailer air supply control does?, Describe what the service air line does? and more.