So I learned some things about the clock/speedo. It is Stemco-Sangamo Tachograph. I'm not sure how Stemco is involved, but from what I found Sangamo produced these, or units like these, between the 40s and 80s. They put these in everything from buses, to tow trucks, to semis. It is almost entirely mechanical, with only three wires on the back. One is the ground, one is the backlight, and I'm guessing the other one is constant or ignition.
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This is a tachograph, so it's meant to clock the speed of a vehicle over a given amount of time. The way it does this is really simple yet really cool.
Inside the cubby on the left is where you can set and wind the clock. The clock will only run for 24 hours before you have to wind it again. The center circle with the rectangle is where you would put the sheet that records the speed.
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The three needles under the speedometer is how the speed gets recorded. The center one records the speed of the truck. I'm not sure how the top and bottom needles work, but I know the bottom is where 0 mph is, and the top is 70. As the sheet spins the speed gets recorded. I have absolutely no info on what the sheet looks like or anything like that but I am going to try and find something to see it work.
So like I said, this thing is almost entirely mechanical. The way the speedo works is really cool. I don't know if this is how all mechanical speedos work, but this one uses centripetal force and a bunch of springs. As the truck speeds up, the weights on the left spread out, stretching a spring that moves up the needle and also sets the speedo. At least that's how I think it works.
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This whole unit is really cool and works completely fine from what I can tell. The clock seems to keep time really well. I don't know what I'm going to do with this but I'm glad I have it.
That's all for now! I'm looking forward to learning more about this unit and how it works. I'm getting closer and closer to when I can start working on Walter again, so as soon as that happens I'll be sure to update you guys.