apple macbook pro a1286 emac 2324 teardown

Seems the slide axle trailer, (Landoll type) guys would like to be able to lock the tractor brakes solid to allow the trailer to be operated on an incline. My 73 RL has a TP-3 valve and the blue knob in the dash cannot be pushed in as it has air pressure on both sides of the piston. I wonder if this is because of the 'update' to a TP-3 as there is a PP7 in the dash for the trailer brakes? You can push it in but there is no detent and it is like squeezing a rubber ball. Sounds like it, but I had thought the blue would be dead and bypassed after the changeover.Sounds like youres is ' looped '.Hey Glenn, want to chime in on this?,lol.

Theres an amazing wealth of info in the Bendix literature library.

Tech updates, Service bulletins, disconiuations, plumbing diagrams, past and present catalog pages with part numbers.I found valves in there for functions I didnt even know were possible, amazing what you can do with air.Takes awhile to read thru it, but very educational.Not just for brake valves, lots of other info there too.John

Apple macbook pro a1286 emac 2324 teardown