The trailer hand valve (also called the trolley valve or Johnson bar) works the trailer brakes. The trailer hand valve is used only to test the trailer brakes. It is not used 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 trailers.
How does a trailer hand brake work?
THE ENERGISER In the electric trailer brake scenario, if you apply the brakes on the tow vehicle the electrical current that is consequently flowing to the trailer’s drum brakes energises a magnet, which applies pressure to levers that in turn exerts pressure on the brake shoes.
Why should you not use the trailer hand valve?
Trailer Hand Valve Do not use it in driving because of the danger of making the trailer skid. The foot brake sends air to all the brakes on the vehicle (including the trailer(s). There is much less danger of causing a skid or jackknife when using just the foot brake.
When should you use a hand valve?
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. Using it while a vehicle is in motion could cause a skid.
How do you disengage trailer brakes?
The easiest option would be to simply unplug your brake controller. If the brake controller is disconnected, the brakes will not receive power. If your brake controller was hardwired and cannot be unplugged, you could cut the brake output wire anywhere between the brake controller and the trailer brakes.
When should the trailer hand valve be used?
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.
What might happen if the trailer is too high when you try to couple?
What might happen if the trailer is too high when you try to couple? If the trailer is too low, the tractor may stike and damage the trailer nose; if the trailer is too high, it may not couple correctly. If there is space something is wrong and the trailer would come loose very easily.
Which is trailer hand valve or tractor protection valve?
Trailer Service Brakes = Trailer Hand Valve lever (which many newer trucks no longer have) = Service line which runs to trailer brakes, blue line Trailer Emergency Brakes = Trailer Air Supply Control Valve/Tractor Protection Valve (red knob) = Supply/Emergency line which runs to the trailer emergency brakes, red line
Is there a charge for trailer hand brakes?
There is no charge for this service, but standard message and data rates may apply. WI. I ran Containers in the late 80`s to about 97, and the boss wanted us to stop, using the hand valve, to save on his tractor brakes. Back then, that was his theory. I always test the hand valve , to see what it takes, for the trailer brakes to grab.
Can a hand brake be used on a skid trailer?
To couple or uncouple the trailer. In the event that the tractor goes into a skid, gentle brake applications using the hand valve may be of some use in trying to straighten out the unit (never apply the hand valve if the trailer goes into a skid). CAUTION: The hand valve is not to be used as a parking brake.
When does a trailer air brake valve close?
To prevent all of the air from being lost, the trailer supply valve is designed to close automatically. If the valve is open and air escapes or, if the trailer breaks loose from the towing vehicle, the valve closes automatically when air pressure in the trailer supply line drops to between 138 and 311 kPa (20 and 45 psi ).
