Cullman Wheel Co.

Cullman Silent Drive

Cullman
Installed
Cullman
Cullman
Installed Less Suppport arm
Cullman
Cullman
Cullman
Support arm welded up
Cullman

Cullman Wheel Co. was one of two of what we now call 'aftermarket manufacturers' who made conversion kits for lathes originally designed to be powered from a lineshaft. The other was Lima. This article will focus on the Cullman often called a "Silent Drive".

Until the electric motor became common in the early 20th century, the common and customary way to power machine tools of all types was via flat belt dropping from a lineshaft in the ceiling of the factory. Truly the lineshaft was the 19th century way of powering a factory. It could be turned by what ever powersource the factory had such as water power, or more commonly in the latter part of the 19th century a steam engine, though internal combustion engines could be used. indeed Rudolph Diesel who ended up being credited for inventing the diesel engine was originally commissioned to invent a way to power machinery in German factories that didn't require getting a belt drive to the machinery. His early work involved working with Compressed ammonia to see if he couldn't make remote 'engines' by centrally compressing ammonia, and then converting the energy released by its expansion into mechanical energy.

One of the now unappreciated advantages of the electric motor is that it allowed factory machinery to be placed anywhere and rearranged easily, rather than being confined to where the flatbelt pulleys would line up. By the dawn of the 20th Century, the electric motor was making its way into factories, but alas the machinery was all made for line shafts and overhead flat belts. This provided the business opportunity for Cullman Wheel Co.

They made conversion kits that would allow the old machinery to be powered by an electric motor. In a way the conversion kit was fairly complex because the machine tools that needed to operate at varying speeds (most of them) generally used belt changes on the drive belt as the way of choice to change speeds. Lathes were sold with a multi-step flat belt pulley on the spindle, and they also were proved with an equal sized countershaft designed to be hung in the ceiling, and turned by the line shaft. The countershaft was needed as it could usually be raised and lowered to adjust the belt tension (which also allowed stopping the machine if released) and to move the belt to a different step on the cone. The countershaft would have exactly matching steps (only reversed in order) to the cone on the lathe. The match was such that the belt of the same length could be used on all steps so the belt tightner would work no matter which step the belt was on.

The rotation speed of the counter shaft was similar to something fairly close to the maximum spindle speed of the lathe. A common lathe might have a total of 6 speeds obtained by a couple of belt changes and a set of back gears (a 3 step cone plus back gears makes for 6 speeds) In this common combination for smaller lathes, the countershaft would be turning at the speed of the spindle just 1 gear down from the highest possible spindle speed (with the flat belt in the middle position--where the pulleys are of equal size. The highest gear would be the Big (on the counter shaft) on the little, and lower position would be the little on the big. The back gears when engaged would create a 'big' gear reduction between the cone pulley on the spindle and the spindle itself, and with the multi position belt, this would create 3 more speed choices all lower than the 3 provided when the spindle and the cone were locked together, and the back gears disengaged. It was common for the countershafts to turn at around 200 RPM. Since a common rotation speed for electric motors is 1750 rpm, you can't just run a belt from the electric motor to the lathe and have the problem of conversion solved. You need to provide for speed changes, and to reduce the overall RPM by about an 8:1 ratio.

With the Cullman conversion, You took the pulley provided with the lathe for the countershaft and mounted it on a countershaft right on the Cullman apparatus and used a short belt. This provided you with the same speed changes you had always had. The speed reduction was accomplished via 2 roller chains. the overall reduction was a bit much for a single reduction so they used a compound reduction to keep the gear sizes reasonable. As you can see from the photo of the chain box, there is no shaft as such in the far back end. A sprocket is attached to the motor shaft and it sticks into the box for the first chain which is compounded to a secondary reduction in the middle of the box. Under operating conditions, the box has a splash lid on it, and the box has enough oil in it that the chains dip in the oil. This keeps the chains lubricated as well as the bearings, and keeps the chains quiet as well, thus the claim to be a 'silent drive'. Roller chains don't have to be run in oil, but at high speeds they clatter a lot less and last a lot longer if they do.

Thus the Cullman 'kit' included a big 'dog leg' that bolted to the back of the lathe which provided support for all the mechanism. On the end of the support leg is a rocker bar. On the back of it is a place for the motor to sit, and to the front is the countershaft. with the flat pulley which will be positioned about the spindle with the chain box to the outside. Then there are two additonal arms which I'll talk about in a moment that hold 'props' which rest on some convenient place on top of the spindle---usually a bolt on the spindle cap which hold the countershaft up. These supports have a cam in them to change length which will effectively raise or lower the countershaft thus tightening the belt, and permitting belt changes just as before. The user thus ends with a countershaft driven flatbelt powered lathe exactly as it came from the factory, but instead of the belt going to the ceiling, It goes up just a few feet where it is ultimately turned by an electric motor. Additionally the lathe can be stopped by stopping the motor, and if the motor is reversible--the lathe can also be reversed by counterrotating the motor.

Lima Drive
Lima Drive
Lima Drive
Lima Drive
Lima Drive
Lima Drive

The Lima kit was more radical in its change. While it was similarly located overhead, it used speed reducing gears instead of a chain, and included a shiftable transmission. In this way a belt went to just one of the cone steps and was permanently installed there eliminating the need for belt changes as you could now shift gears in the Lima transmission to get different speeds instead of moving the belt (the back gears remain available in any event).

A significant issue with both kits are that they make the lathe fairly top heavy. The support leg isn't strong enough that you would want to lift the lathe by it, but collectively the mechanism is enough to considerably raise the center of gravity which explains why the mechanism was removed by me when I moved the lathe.

- - Updated 12/29/2012
- - Updated 1/06/2010