My wife came back from the in-laws house with more tools from my father-in-law. I found another JOTRU 10A!!!. This one has a ratcheting head and breaks at 75 inch pounds. It also has an interesting hand etched series of numbers on the shank: "527A04007-13". What say you, Grayspoked?
NK:
First, my apologies for this delayed response. Life has been busy of late!
I expect that this is another of the Van Belknap specials. Those are tools that Dad's Detroit salesman (before he founded his own company, that still exists), Van Belknap, ordered up to try to convince the automotive industry to buy Jo-Line torque tools. I have no idea now, over 60 years later, what Van had in mind with a 75 inch-pounder. My experience was that the automotive industry bought lots of the 30-250 ft-lb "Size 3" wrenches, with inch pounders being a distinct afterthought. Maybe that's why Van was unsuccessful in selling more of these like yours.....
Anyway, back to the tool at hand.
It has the two patent numbers, 2743638 and 3016773. That places it on the earlier end of things. Later tools had three patent numbers on them. The "SERIES A" marking does the same. Jo-Line got up to SERIES D before Dad sold the Company to KD in late 1979.
The notation on the spring tube that it was manufactured in South Gate ought to put an end date to the inquiry. Jo-Line moved to Anaheim in the fall of 1968. Thus, I don't think it possible that your tool was manufactured after 1968. Of course, it's possible that Les Trimble grabbed a South Gate spring tube out of the tool crib in 1969-1970 because yours was a one-off and the place of manufacture was therefore meaningless. I don't give that theory much credence, though. I started working at Jo-Line in June 1969, and I never saw a South Gate-marked spring tube, ever.
The name stamped on the spring tube, "Jo-Line" dates your tool to the time after the company changed its name from J O to Jo-Line. Dad told me that this change occurred in the 1962-1963 time frame.
The finish on your spring tube is what we called a "satin" finish. It wasn't terribly popular (not putting down your tool - it's just that Jo-Line put me through school on its chrome-plated models, not the satins like yours) overall, and more of them were seen earlier in Jo-Line's lifetime than later in my experience.
The ratcheted JOTRUs had any number of different ratchets on them. Dad didn't begin making Jo-Line ratchets based on the Facom design until the early 1970's. Yours looks like one of the New Britain ratchets, of which I saw a lot in the 1969-1972 (or so) era.
Unfortunately, the etched number on the spring tube was placed there by an owner of your tool, and not by Jo-Line. Had I received your tool for a refit while I was working in the repair room. I'd have swapped out the engraved spring tube for a clean and unmarked one.
So, time for bottom lines. I think your JOTRU 10A is a one-off Van Belknap special manufactured between 1962 and 1968, and probably closer to the 1962 end of that range. Why it was built - for what purpose - I cannot now tell you. Good to hear that it has maintained its setting after all these years. The tools I got in the repair room had pretty much stayed calibrated, but I never had the chance to see a 60 year old tool while I was working at Jo-Line.
I have fielded a number of other inquiries in this thread regarding JOTRU 10s - see Posts Numbered 23, 25, 28, 48, and 75. I also discussed your patent numbers at Post 43.
Enjoy your tool! I suspect that there are not many like it out there.
Bill