Spoker D at JD celebration in KS

A friend was invited to take his JD pulling tractor to west of KC for a kickoff of the 100 celebration. He showed me a picture of a spoker that had a reduction gear on the pulley. He thought it was on there to pull a thresher down the road better. I know there were higher gears in the rear end to be able to go faster. I think it may have been to run the thresher better with the pulley using a belt.

Any ideas. Thanks.

Heck, go out on a limb, and show us a photo of what you are talking about!

Sounds like it was a super-rare AD665 speed reducer. The picture is of one installed on the Read family?s earliest known surviving spoker ?D?. The speed reducer was developed to give slower travel speeds for such things as pulling a combine or other implements through heavy crops or when working on hillsides.

The reducer was attached to the crankshaft and was partially inside and partially outside of the belt pulley. The standard clutch driving disc and the outside clutch adjusting plate were removed and replaced with similar parts in the speed reducer. With the reducer installed, power from the crankshaft went through two spur gear reductions before being delivered to the special replacement clutch driving disc. So instead of the clutch disc spinning at engine speed, the clutch disc would now be spinning at a reduced speed. Accordingly, the belt pulley and the rest of the gear train would also be spinning slower.

That big channel-shaped bracket between the reducer and the engine block not only helped support the weight of the reducer, but also absorbed the torque generated by the gear reducer. Without that bracket, the reducer would spin freely and the tractor wouldn?t move.

The belt pulley speed was reduced to 545 RPM (normally 900) and travel speed in low gear was reduced to 1.65 MPH and to 2.25 MPH in high gear.

However, a disadvantage of the speed reducer was that the tractor travel speeds (and belt and Power Shaft speeds) were permanently reduced with the reducer in place. You couldn?t shift it in or out. So if you needed to do belt work or travel faster, you had to remove all that stuff and reinstall the original clutch disc and outside clutch adjusting plate.

That has some similarity to the clutch on the bath tub D of Dan Thomas. That has a bearing on the outboard of the clutch.