Adding a Trailer Brake Control Valve to an M35A2

[Wildchild467]

I recently got a trailer brake control valve from an M931A2 and would like to put it on my M35A2 so I can manually apply trailer brakes. They also call these a Johnny Bar, Johnson Bar, etc. It had 3 lines coming out of the back and I was curious where they need to be routed to. One of the ports says Supply, one says Exh. (exhaust I think) and I don't know what the other one says. I have researched for over and hour, looking at M275A2 air line diagrams and I still don't know how to plum it up. I can make a guess, which I think I have a good hunch, but I wanted to confirm. One guy said it plumbs right inline with the line that goes to the service side trailer line, and then just add an air supply line from under the dash..... But again, I wanted to confirm. Looking at the schematics there is also a tractor protection valve that I could install in addition to the trailer brake control valve, but I don't think I need it right now. I rarely ever pull an air brake trailer and I don't know how the tractor protection valve would interfere with me using the emergency glad hand as a port to hook my air hose up to fill tires and stuff.

The TM that shows the M275A2 air brake routing diagram is TM 9-2320-209-20P

Any information on adding one of these trailer brake control valves to my M35A2 would be appreciated. Thank you!

 

[topo]

I think you need a double check valve ? one from a m52A2 may work .I added one when I made a m211 in to a tractor .

 

[Wildchild467]

I think this valve has the double check valve built in it.

 

[Wildchild467]

I see a double check valve in the system, not sure if I need one of those or not?

Can I use an air system diagram of an M818 and use that as a reference to install mine?

 

[topo]

With out a double check valve if you pull down on the lever you would put air to the trailer and the truck brakes I think because the brakes on your truck can be applied when using the glad hands on the front of the truck when towing . On the hand brake lever you have a supply line in and a line that runs to the double valve .On the double valve you have the line from the hand valve and a line from the air hydraulic unit I will have to look where the other lines go . The diagram from the M818 should work I have never been able to see how it is set up .

 

[rosco]

I don't know what a "double check valve" is, but I think that all you need is a simple check valve. Mount the thing on the steering column, supply air from under the dash, and the output line is tapped into your Service line. The check valve goes upstream from where you tap into the Service line. If you don't have the check valve, you will charge your brakes. The check valve thus allows you to apply all brakes w/trailer, or just to apply trailer brakes.

Note: A Tractor Protection Valve will operate in addition to a trolley valve. If you pull a full air brake trailer, it will give you a real parking brake, otherwise, there is hardly any way to set the brakes on the trailer.

 

[topo]

pictures of double check valve and air hydraulic cylinder .The line from the AHC follows the cross member and goes into the DCV .The other 3/8 line comes from the hand brake valve on the steering column .The large line in the back goes to the rear glad hand and tees to the other glad hand for the fifth wheel trailer witch in this case it will be caped.

 

[Wildchild467]

I made this diagram by looking at a M818 air system diagram. It appears there are a couple check valves that are used. One for the trolley brakes and one for the brakes on the truck if the truck is bring towed and using the glad hands in the front. Now, I made the assumption that the one valve is not needed if only installing a trolley brake handle. With that assumption, I marked the diagram in blue lines showing the lines that can be omitted and the one line that should be connected. This is the best example I can come up with if I were to put a trolley brake on my deuce.

 

[rustystud]

View attachment Scan0148.pdf

This is what your looking for.