How old are you? They were going out of style in the mid-1950's when I started hanging out in the shop at age 10. On the old inlines with lots of room under the engine, a small high speed grinder with a brass hook on it could be hung over the rod journal, and it would follow the crank around as a slow speed electric motor turned one rear wheel with the transmission in high gear.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!