doubleclutchinweasel

I’ll never forget those cracker box Jimmies screaming at the top of their lungs. The smell was awesome…especially when hooked to a cattle trailer! LOL!

There ya’ go!!!

Yeah. That's pretty weird!

No kidding!

If you've ever converted a Cadillac to a pickup truck...

Yes, Geoff. One was older. One of the ones where the red button stayed in was a ‘67. The last one I had, where the red button popped with the yellow button, was a ‘70. Not sure how that aligns with the new regulations. Not sure if those setups were factory on both or not. I only drove 1 truck that had all 3 buttons. It was a Peterbilt. I can't remember for sure if the blue, tractor brake button popped out when the yellow was applied. But, I don't THINIK it did. But I can't remember that for certain either way. Funny how the older the memory, the clearer.

Oh, on both of those, the yellow button still applied tractor and trailer brakes when pulled. The yellow “system” button was first in line. So, when it was pulled, it dumped air out of both systems and applied the brakes. The only difference was whether or not you had to push the red trailer brake valve in after you pushed the yellow button in.

I’ve driven Mack’s with 2 different “red” buttons. On some, the red would stay in even when the yellow was pulled. On others, the red would pop out when the yellow was pulled. Difference is one was spring loaded and the other was not.

You only need the blue valve to set the tractor brakes and leave the trailer brakes free to roll. Is kinda important with the roll-back type trailers. The Landoll Haul-all trailers need this setup. Other than that, not really much need for it.

You got the most important part! Looks nice.

That is what I thought was so cool about the one I was using. The multiple PTO speeds.

Almost sorry I asked a question! Anyway, I finally remembered something about that truck I was talking about. The PTO did actually attach to the compound case, not to the main case. I found a picture of one that reminded me of that. That would explain why the main had to be in gear for it to turn, and why changing gears in the main box changed the speed of the PTO. Of course, since I was just a young 'un, I HAD to try putting the main in neutral just to see if the note on the shifter plate was correct. It was. With front box in neutral, regardless of compound gear, the PTO did not run. From looking at pictures of these old boxes, I see there were some that DID attach to the front box, which would mean the front box could be left in neutral and the PTO would still be live, just like TJC said. That matches what the guys were saying about the countershafts in the front box driving the PTO. So, I guess this is a case of everybody being right, for the trans they were using. Apparently, there were indeed different setups on the PTO. Not sure if this is an "old" vs, "new" trans thing, or just a variation in how they could be set up. Or if it varied from model to model. Don't know. But, as usual, I learned something. Always do when this bunch is involved.

So, if a PTO is driven off a main box countershaft, it would be live any time the clutch was out. Speed would be constant. If it’s driven off a shaft in the compound, the main box gear selection would determine the speed, and would have to be in gear to rotate the compound input shaft. So, I guess there would be several ways to set that up. Very interesting stuff. Great discussion.

Did you plumb in both the Tull flow and the bypass lines?

This is what we had... If you wanted to sit still and raise the bed, put the compound in neutral and the main in gear. If you wanted to move wile raising it, put the compound in gear and pick the main gear that suited the situation.

That's why I am so interested in what TJC said! I'd really like to know how that setup he mentioned worked.

I'm sure you'll figure it out as soon as you engage it. Just let us know what all you learn!

Good point.

Not sure which trans the OP has, but here is some verbiage from a service manual that talks about air-shifted aux versions... This particular group works like the one I remember using...neutral on the rear box for PTO. But, again, this may not be the right group for the OP.

Thanks!

Yeah, I may have spoken out of ignorance! I'm thinking back to a particular truck I remember. It had a 2-stick Maxitorque "Extended Range 6-Speed". On that one, if the mainshaft wasn't turning, there was nothing happening in the rear box either. Not sure where the PTO was mounted on it, though. That one required the front box to be in gear to spin the PTO. But, you had a selection of PTO speeds to choose from, which was useful sometimes. But, since the countershafts are powered even when the front box is in neutral, I suppose you could power the PTO off of one of them, albeit at a constant ratio. TJC, you've got me curious. What box did you have where there was power coming off the auxiliary when the main was not turning? That's an interesting setup. I'd like to see how they routed the power through that one. Sure would like to know more about that one!

That's what I remember, too, JoJo. Front box had to be in gear. Rear in neutral. Select main gear based on PTO RPM required. But, it has been 42 years for me!

Yeah, the old Oil Clarifiers tended to have issues with the check valves that would cause them to drain when not running. They were great when they worked...having the full flow and the bypass circuits in one unit. Looking forward to seeing yours finished.

Maybe, if you heated the sheet metal around the cowl, and put a jack against the driver's door, and pushed the cab about 11" toward the passenger's side... No! Wait! Sorry! That would make it an R model! Sorry, couldn't resist! Great to see you making some headway.