Model A main drive gear, educate me

[bmklawt]

I have this 3 speed transmission sitting in my garage and the main drive gear is smaller than the main drive gear in my doodlebug project. What do each of these fit, just curious.
Top one is 1-1/8" 6 spline, the bottom is 1-3/8" 10 spline

 

[Bob C]

Top looks like for a multiple disk clutch.

 

[rocket1]

appears to be part # A7017 AR transmission main drive for 28 multi disc clutch.

 

[katy]

What kind of engine is that?

 

[Sunnybrook Farm]

Wow that is neat, describe what is there a little bit. You have done a lot of work!

 

[rotorwrench]

Looks like a John Deere model L or LA engine. The model AA trucks eventually got a 4-speed but it took a few years to get one in for them. Some earlier AA trucks had under drive gearboxes added on for pulling heavy loads. It doesn't look like you have enough room for anything like that.

The 1 3/8" 10-spline is the common size for most of the early Fords.

 

[bmklawt]

It is John Deere LUC motor off a 12A combine the motor was also used an the L and LA tractors, on the motor there is a clutch off an LA tractor then an adapter I made to marry the Model A 3 speed transmission to the clutch.

It's a glorified scooter I am making for my 90 year old father to tool around in at tractor shows, they don't allow golf carts at most of the shows and my father can only walk around for an hour then he's done for the day.
The problem is I can only get this to down to 9 mph which is really moving when your in a crowd of people. I'm currently looking for a 4 speed transmission to use with an underdrive I currently have to hopefully get this down to walking speed.

 

[rotorwrench]

You can also look for a low gear rear axle ring & pinion but it might not be low enough.

 

[katy]

If'n you could squeeze another 3 speed transmission in that driveline you could really slow it down. A friend built one years ago and when both transmissions were in 1st gear it barely moved when the engine was idling.