My last post on helix angles and the constraining theories adopted at some shops reminded me that younger readers might not be aware that there was at one time much more diversity of opinion in the gear design community. Over the past 40 years, the internationalization of the marketplace has caused a convergence in gear design. This should not be a huge surprise to anyone. When the best engineering minds in the world have that long to work on the same problem the science and collective experience pushes them to the same solution. You may think you are a maverick freethinker with unique insights to an application. Unless you can prove it with a breakthrough product, the world will leave you behind for the boring but proven alternative. For many motor sports fans, the month of May was a clash of ideas at the Indianapolis 500. We old timers tend to imagine more diversity in the field than there actually was, but it was a far cry from today’s spec chassis and two engine choices. I started following the race in 1963, a ten-year-old boy who wanted the rear engine revolution to happen immediately. The Lotus-Fords were big news, of course, but there were other rear engine cars that year and in the two previous years. Most of the teams fielded cars powered by 4-cylinder Offenhausers; a powerplant with a lineage dating back to the Millers of the 1920s. Hot-rodder Mickey Thompson entered homebuilt “flying frisbee” shaped cars with aluminum Buick V-8s. There were also cars with 6-cylinder engines from Leo Goosen, the designer of the venerable “Offy.” For the second year in a row, a gas turbine car attempted to qualify. I mention the later because not all “world beaters” succeed immediately. The 1967 STP turbine car and the later Lotus-Turbines did not just drop from the sky, ready to shock the racing world. The gear industry when I started in 1971 had many competing tooth forms, heat treatments, and design philosophies. Today, we seldom encounter a new enclosed commercial speed reducer that does not rely on a carburized, hardened, and ground single helical gear train. The era of thru-hardened, induction hardened, or nitrided as-cut or shaved gears has passed. Herringbones and planetaries had pretty much been rendered uncompetitive before I started but they were in the mills for many years to come. Unlike old race cars, obsolete gearboxes do not get restored. Other than the occasional lobby display, they get melted down for scrap. It is important that we remember the lessons learned from them. Like Grandma Mueller’s lard and onion sandwiches, the makers did the best they could with the ingredients on hand. When the situation changed, so did the sandwich.