# G0602 speed reducer



## Loafy (Apr 30, 2011)

here's a couple of videos of the speed reducer
I also have a reverse tumbler gear set I designed and built for this lathe. using small engine timing gears.
this speed reducer is built from casting and again small engine gears. the odd shape is due to making it clear the pulleys/gears on the lathe, which I then had to do a last minute change, seems the 2 drive belts interfered with each other so I had to rotate the assembly to keep the belts from rubbing.
[video=youtube;qopnUPtaAnU] http://www.youtube.com/watch?v=qopnUPtaAnU [/video]

[video=youtube;Pd9_qZR7P0w] http://www.youtube.com/watch?v=Pd9_qZR7P0w [/video]
I should add that when not in use I remove the speed reducer. It is held on by one 3/8" bolt so it goes on and comes off easily. The torque at the spindle is very high if you accidentally got caught by the work or chuck its going to be a very slow and painful experience. If you do this modification with the spindle running slow DO NOT get careless.


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## Pacer (Apr 30, 2011)

That is way neat - that little 9x20 aint known for its slow speed, and, for having fwd/rev feed either.

Your casting of the pulleys remind me of some tidbits of the lineage of that lathe - and, of a recent project I did in casting.

You may be aware of it, but maybe others arent - the 9x20's (and a couple others) were cloned by the Chinese off the 8 and 10" Emco Maier lathes from Austria, a _lot_ of similarities. 

I have a Emco Compact 10 I received as a basket case and was missing all the motor and mounting plate with the 2 reducing pulleys. After a Googling spree I finally made contact with _ONE_ other owner of a Compact 10 and he was generous enough to furnish the dimensions for the plate/pulleys. So, like you, I cast them. I retained the original design using those small gates belts, but seeing yours and thinking back on it I should've went ahead with another type belt. Since I didnt have a motor to start with, I used a treadmill motor to gain variable speed - and those real slow speeds that are so nice to have.

You can sure see some similarities here to the 9x20 ---


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## Loafy (Apr 30, 2011)

Yes it has very high torque.


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## Loafy (May 2, 2011)

There is 3 gears in the speed reducer. Two crank shaft timing gears and one timing gear makes a 2 to 1 speed change. To get the speed slower with the speed reducer the in put pulley needs to be larger than the out put pulley. The reason for using 3 gears is for rotation. The input rotates clock wise, the intermediate gear will rotate counter clock wise, causing the out put gear to rotate clock wise.
To get the proper 2 to1 ratio the input gear has to match the out put gear in ratio, you can use a larger or small intermediate gear, and the input and out put will be the same. The more distance you can get between the in put and out put shafts will allow you to play with larger pulley sizes, to either speed up the reducer or slow it down. I used timing gears out of a briggs 5 hp engine.


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