Tractor Protection Valve

Your red button "trailer supply" protects the system from a pressure loss. The trailer breaking away or losing your red glad hand connection does NOT cause the red valve to pop. It may take some while for the loss of air pressure to be enough for the red valve to pop.

Once it does pop you are correct as described, this causes no air pressure in the red emergency/supply side. The valve at the back of the cab then shuts off the blue "service" side. Think of the rear valve as a slave to the red button.

 

Yep. Red button (trailer supply) is what protects your tractor air supply in the event of a trailer supply line break. The only purpose of the tractor protection valve you pictured is to stop air from flowing out your tractor service line when you step on the brakes bobtail. Its basically a pilot operated shutoff valve actuated by trailer supply line pressure.

 

The OP appears to be correct in his description of the tractor protection valve. In the diagram the spring on the valve should be towards the service side of the system. A small detail in the diagram but the OP seems correct.

The tractor protection valve is so named because it does indeed protect air pressure. As we all know it can be some time after the service line is opened until the trailer supply button pops. In a situation where the trailer emergency line is broke, air pressure must be conserved in order to operate a vehicle safely off the road. Once air pressure is dropped, by a line break for example, on the emergency side of the trailer protection valve the service side of the trailer is cut off. This conserves air pressure to allow a tractor to be operated until it is safely stopped off the road should an emergency line break or trailer become disconnected.

There is a short time after the trailer air supply pops and the tractor parking brake pops. If no attempt is made to conserve air pressure, a drive may not have the time to safely move a disabled tractor off the road. Hence the tractor protection valve.

 

If i have a tractor converted to a dump truck can i eliminate this valve?

 

You don't have to do anything. It only functions when the red button is pushed in anyway.

 

Im having issues with the rear brakes locking up it has a bp-1 relay proportioning vqlv3.

 

Did you get this issue resolved? I'm having similar issue. It seems like only the yellow knob is working properly. Kind of curious if the dash valve can half break?

 

You may have bad brake Chambers and they may have the spring in them broken or the diaphragm is bad and the spring is just sprung.

 

With winter and ice here I'm having a hell of a time. The drives with the spring brake locked up on me. After a day and a half of heating valves up and running alcohol through the compressor line the yellow park brake decided to act normal. Even though the temp hasn't been above freezing. It's weird. Drove the truck home after the poark brake released. But now when I push the trailer valve in, there should be a mass flow if air coming out the red glad hand but there's nothing.