I have been under the opinion that this unit was for driving a tachometer. There are 23 teeth on the large dual gear that runs off the generator's 16 tooth gear and 30 teeth on the small gear of the dual gear which drives the 34 tooth final drive gear that spins the output shaft. It so happens the final drive gear has a square socket hole that a 1/4 inch socket extension fits just right in. Can someone tell what the RPM of the final drive is by using the figures I supplied?
You could count teeth and determine the ratio, or turn the crank one revolution and see what you get. I bet it turns at the same speed as the camshaft.
Assuming no two gears are on the same shaft, the ratio is the number of teeth on the final drive gear divided by the number of teeth on the crankshaft. All the other gears in between don't matter.
Oops. I see there ARE two gears on the same shaft. Let me get back to you.
OK. I'm getting 0.92:1.
I'm pretty sure the crankshaft has 24 teeth, so:
24/23 x 30/34 = 0.92
So, at 1000 rpm your output shaft is doing 920.
assume 1000rpm at the crankshaft gear with 24 teeth
This drives the 96 tooth camshaft gear at 250rpm
which drives the 16 tooth generator gear at 1500 rpm
which then drives the 23 tooth gear at 1043.478 rpm
The 23 tooth gear shares the same shaft with the 30 tooth gear, so their rpm is the same.
The 30 tooth gear at 1043.478rpm drives the 34 tooth gear at 920.716 rpm.
Assuming my tooth counts are all correct, the final shaft speed is ~92% of engine RPM.
Hal either types faster, or thinks faster than me.
Actually, the cam gear only has 48 teeth, but they don't come into play.
Ooops... was (incorrectly) thinking cam spins 1/4 engine rpm rather than 1/2.