Brake service line question.

Hi Deezl, you mean, apply the wagon brakes with the "johnny bar"? You should be able to still apply the truck brakes with the foot pedal.

 

Why not just install a mutifunction valve and put full chambers on the axles. The multifunction valve supplies air to release brakes and air for service brakes. Its the same valve used in most trailers.

 

no.if you apply pressure to blue glad hand and truck service brake is not applied, trailer control valve (under cab usually) is open and air will go out throught valve exaust

 

ahh nice one. You have a dual line system available at the back of the towing truck right?
I would connect the emergency (red hose) to the supply port of the 4 way/multi circuit protection valve (port1)
to connect front brakes on dead semi. cut pipes going to the brake chambers "t" with pipe that you install at port number number 2 (delivery) on the relay/load sensing valve at the drive axles.
then connect your service line from the towing truck to port number 4 (service) on the relay/load sensing valve.

and the truck will react like a trailer.

hope this help
ps: make sure the park brake is released on the dead semi. because it will still function. or remove the park brake and connect the pipes direct on each other (bypass it)