So here is another article from the engineering magazines, that I scanned the other day. This one is from the March 1978 "Machine Design" magazine.
Regulating speed mechanically has taken a big hit with the advancements being made in AC and DC speed regulation in electrically driven equipment. For all other powered drives there is mechanical speed regulation. This article gives a quick description of the most used forms of these methods of speed regulation.
Of greatest interest to the "I can build it myself" workshop addict is the Traction and Variable-Pitch methods. The Hydrostatic method is used in things like your garden tractor, though much larger equipment has been run with Hydrostatic transmissions. Variable stroke is used mostly in manufacturing processes, the torque converter in your car operates on the Hydrokinetic principle and the Hydroviscious method can handle huge amounts of HP and is mostly used in large industrial applications.
Traction, the first of the two methods more common to the home diy'er, has been around for a long time. It saw use in the days of steam, though you don't often see it anymore. It is relatively easy to construct and can give good control of things that require quickly changing feed rates and disengagements. Here is a picture from Fine Woodworking # 17, of a circular sawmill build, that uses this method to control the carriage. Two handles control the start, stop, speed, and direction.
Variable-Pitch is the other more common method of speed control for the home diy'er. I have never followed up to see who the inventor was, but they used to be called Reeves Drives and many units were manufactured under that name for light duty to very heavy industrial applications. They may have been the original inventors, however when the patent ran out it was adapted to a larger variety of applications. It is used to run drill presses, in the picture below, the Shopsmith combination woodworking machine, snow machines use this method, and even automobiles have been built using this method of speed regulation. In 1959 the Dutch sold a car in North America called the DAF, (maybe this is where the term DAFT came from, lol, just kidding), that ran on a Variable-Pitch drive.
So enough about what I know, here is what "Machine Design" knows.
Hope you enjoyed this little read.