Adjusting the speeds on machine spindles is something that the machinist must do for various jobs. Companies have often searched for solutions to the time involved in this process. Large production shops with 3 phase power often use variable frequency drive 3 phase motors, some huge companies actually run their spindles with hydraulic motors with pressure supplied by a big centralized pump feeding the various machines. For the home shop, the best solution is the tried and true method of an AC motor running at a constant speed and varying its speeds through a series of belt reductions. This method produces far more useable power than even the more expensive DC variable speed motor system. Our challenge was to devise a simple and reliable way of changing the belts in the shortest possible time. The key to success in this is to maintain equal tension on each belt. We solved the problem by designing an idler pulley with dual motion in one adjuster.
