US Patent 7470206 Multi-speed countershaft transmission with a planetary gear set

A transmission is provided that combines first and second countershafts with a planetary gear set, and uses first and second head gear sets to provide ratio. Each of the countershafts supports gears in no more than five co-planar, intermeshing gear sets (and in most embodiments no more than four co-planar, intermeshing gear sets), thus minimizing the overall length of the countershafts. The transmission provides at least nine forward speed ratios and a reverse speed ratio and utilizes only eight torque-transmitting mechanisms.