This amazing bit of gearing has appeared on HowStuffWorks before. You might realize it from the electric screwdriver post. An automatic transmission includes two entire planetary gearsets folded alongside one another into just one element. See How Equipment Ratios Perform for an introduction to planetary gearsets. The friction bands are https://johnnytxywt.ssnblog.com/33217154/a-review-of-gearbox-auto