doubleclutchinweasel

Parking Brake Valve with Anti-Compounding Function (one way to do it, anyhow). PP-2.pdf Pretty sure this was it...

I have schematics for the later (R) brake plumbing. But, I saw a link to this site that had schematics from people who had already converted their Bs to spring brakes. So, you should have plenty of information at your disposal. The air systems really are not all that complicated once you understand what is being done. You shouldn't have any issues getting it plumbed in and working the way you want. Here is a link to one of them. A Google search will show you others. One think I do encourage in a spring brake setup is the use of an anti-compounding valve to keep from applying the service brake and parking brake at the same time. The way mine was done from the factory was really simple and did not require a separate valve. Mack used a specific push-pull valve for the parking brake which had the exhaust side plumbed in by a small line to the service brakes. This way, if you applied service brakes, that pressure went into the release side of the parking brake and negated some of the spring force. Voila! Anti-compounding! Then, when the parking brakes were released, the exhaust port was closed and the service brakes worked normally.

LTK, are you going to upgrade the truck to modern spring brakes? If so, you may not need to worry about some of the "old" parts. You can set it up like a more modern piece, and use current valves. I tool the DD3 chambers and inversion valve off my '70, and used piggyback chambers with spring-loaded parking and emergency brakes. What I ended up with was far simpler than what I started out with. Seen lots of B-models with a parking brake valve added to the dash.

Inversion valve was a predecessor to spring brakes. If the air pressure dropped, the inversion valve sent air from an emergency reservoir to the parking brake chamber of a DD3 type chamber. I don’t think that’s what it is though.

They could have been different back then, couldn’t they?

I wondered about an inversion valve, but I've never seen one that looked like that!

No numbers? Could that be some kind of pressure reducing valve? If you will PM me an email address, I will try to send you some catalogs that might be useful to you...IF the file size isn't too large.

Boy! That would be a pisser! Wouldn't it?!!

If the PTO is driven off the rear box, the gear selection in the front box will determine the RPM, just like Terry said above. With the front box in Neutral, the gears may just be free-wheeling. I have seen pictures of PTOs mounted on the front box, driven off a countershaft. Those would be live any time the clutch is engaged.

All the old stuff I ever saw had 2 6V batteries in series on each side, making for a 12V system. Many times those got replaced by a single 12V battery on each side. SOME had the relay to bridge the 2 12V sets in series to run a 24V starter. Some just had 12V starters. As far as I know, all the stuff that vintage was originally positive ground. I never was around any gas powered stuff. All ours were diesels.

Agree on the chasers. Sometimes taps and dies do cut more than expected. Just need to clean them up. I have used both though.

Finally got to see the last 2 videos. Love it! Love the sound, too! Only thing that would make it better is if it lived in my driveway.

I'm sure somebody will know for sure, but I THINK that section was rigid originally. But, do you have any idea how long it has been since I saw an original one?!

Brocky sent me a picture this morning of an unusual H-model. I happened to have the same picture. It is listed as an H628 in my book. Mack shows only 2 of these made in 1955, Apparently a variant on the H62 chassis, this should have been gas-powered. I saw the picture years ago, but never bothered to check on the rarity of the beast. Indeed, one of the most rare. I think the company was in Winston-Salem, NC. I think they were called Piedmont Concrete Company before this. Gone now, I believe. Thanks to Brocky for pointing this one out!

I watched the whole thing. All makes perfect sense to me.

I wonder the same thing. Maybe the F was already in the works when the G was ready?

That's funny. Even if there is no connection between manufacturers, it is likely that different manufacturers could arrive at similar designs. Happens all the time!

I wonder how much of the grille they reused from the H (top) on the G (bottom).

There are 2 or 3 guys on here regularly who know these things inside and out, and you were talking to one of them above. They'll steer you right. Have no fear!

I'll have to see if anybody feels like going with me. Not sure if the Mrs. will feel up to it. Maybe one of the grand-horses will want to go.

I've never been to this one. But, I see it is only about 2 hours from here...

I think you qualify for at least an honorary title, Jo-Jo.

I like those!

G's were...different! Looked kinda like an H from the front, and more like the later F from the side. Not too many of them made. Only offered for a total of 3 model years.

No, I don't have any of those. But, there have been several threads on here discussing interior colors over the years. A search might bring up some old threads. He mentions the light green of the early models. I'm glad to hear somebody is working on some of those early ones. I liked that better than the darker green of the next ones. The light green always reminded me of the color of the inside of a school bus!