Geoff Weeks

Yeah, the "N" was a neat set-up, but I think its weak point was high speed running, not a problem on WW2 trucks it was used on, but could be when re purposed later in life. I think that is why it was never seen later in civi production trucks.

If the front lugs are 1/2", the nuts are still available last time I looked, but the bolts are not. They are a special bolt and are held in the spoke with a cotter pin. I think the 5/8" of the same style are still available IIRC. So be very careful removing the nuts not to snap the bolts.

Up until the late 50's early 60's when the more common treadle valve came into being, this was what was used. I tried to get a photo of my Dart (early 50's) but couldn't This is from a military air brake manual

Coupla things to add, In that vintage you can't look at the pedals and tell if it was air or hydraulic brakes. The air brakes were often controlled by a rod from the pedal. This allowed mfg to use the same pedal on air and hydraulic braked trucks. I could try and get a picture on my Dart set up it uses the rod for air brakes, but just the same you'd have to look to be sure. However the lack of visible compressor on the engine make hydraulic likely. Drums: inspect the drums carefully as it is unlikely to find replacements still made. NOS or expensive repairs made by pressing in a steel band to restore the drums if they are shot can make a big difference on how you proceed. Worn drums or other parts that are NLA may even dictate a axle swap is in your future, unless parts can be found. In the early years hydraulic brakes were used on much heavier trucks than they are today, air brakes were new and an expensive option that wasn't often opted for unless semi trailers were going to be towed, and sometimes not even then. I once saw a 40K GVW tandem axle Loadstar on juice brakes! Vacuum PDL!

If the 24 volt one you mentioned in the 1st post is 24 vac, it would likely work just fine on 12VDC

It seams a lot of cabover Mfg listed the 3208 as an option, but I have never seen one in a cabover in person. I almost bid on this Astro, 6-71 powered. winning bid was something like $2500 at the ATHS Alburn auction. I have a fair number of miles in on a cabover with 4 spring suspension. Didn't ride much different than my air ride suspension cabover as long as it was properly loaded. Empty both road harsher then when loaded.

My experience is: Filters full of fuel, and it will fire off well before one tank of air is used. Not pre-filling and it will take more than one tank of air. I have changed filters many times on my air start trucks, away from air without a problem. On my Cat powered truck (it has the primer, but I prefer not to use it) I change the primary filter, start the truck and let it pump the air out, then change the secondary. Stumbles and coughs a bit, but that is all. This is without pre filling.

Wash down of bores is more a problem when and engine idles, you get incomplete combustion and condensed fuel on the cyl walls. 'Rolling coal" tends to get hard carbon build up above the top piston ring, wearing (scoring) the bores. Best way to prevent carbon formation is to burn with enough air for complete combustion. Neither are good for an engine.

Put a section of clear line on the suction side (temporarily) and see if it is sucking air. You could also just replace the suction hose, might get it. There are specially made "sight glass" that have flare fittings on them you can buy, but clear hose works temporarily. I've chased my tail on suction air leaks before, learned a valuable lesson. M50043 Sight Glass #10 : Apexinds.com come in other sizes as well

I have a passion for old maps, and running old routes. Sometimes that is not an option in a modern 18 wheel truck, but I have been on some. I have run the old US 10 from Miles City along the north side of the Yellowstone in a truck. Mostly gravel but some pavement. ( had a delivery off of it, and just kept going when my drop was made). Been on most all of US 20 from Boston to Oregon, with the exception of the section around the "sisters" that is restricted. I delivered cell towers, so got off the beaten path fairly often.

If done well, there is no disadvantage to making automatic. Most Mfg did, some better than others. I never had a problem with either Cummins (AFC) or Cats method. Earlier methods by all mfg needed some work. I wouldn't want to have to monitor the boost at all times to have a good running engine. I can think of no advantage to not having the system take care of itself. All of them were adjustable if you knew how.

Not to up on that era Mack stuff, but I always liked the Tip-Turbine set-up. A better solution than Cummins low-flow cooling, for the same problem. How do you aftercool better than engine coolant can? How do you do it and fit the engine into current vehicles without re-designing the front end? Cat didn't try, Cummins tried to "super-cool" the coolant before it entered the engine, Mack decided to pull air from outside the hood, to pass through an air to air inside the hood.

Looks like a solenoid valve for an air fan clutch? no idea why that is there. There looks to be another port at the next intake runner as well. Has a 90 deg fitting that is cut off at the edge of the picture. Any of them would be a place for a boost gauge.

IDK, I had over 200K on mine in a Ford Exploder, pulled trailers no problem, but then again it was on the original clutch as well. Had to come out one time when a mouse nest was in the pressure plate/bell housing. Never dumped the oil in it either. (5 spd).

Picture of the box would help, but if it is like I am thinking, you can delete the cylinder and hose at the box (plug) and it will work. However they are most often used on heavy front axles so the tie rod only has to keep both wheel ends in sync and not transmit the force. When you cut back to just the steering box moving the wheels, the tie rod has to transmit all the force to the passenger side and you can end up bending the tie rod. You would also have less assist if the box is doing it all. I wouldn't recommend deleting the assist on the passenger side, and would only do so to move around the shop or for a hobby truck that isn't loaded. Some of the early P/S boxes were "low pressure" boxes and run much less pressure and therefore power, so may be that is why an assist cyl is needed. Early Sheppard boxes were low pressure boxes, and the assist hoses on the Sheppard box goes to the bottom (opposite the input shaft), and the other to the top-side of the bolt down cap on the input side if the box. Again, pictures and/or steering box model numbers would be of help.