A compact, planetary gear transmission design with low weight-to-horsepower ratio made possible through high energy clutch assemblies, has low impedance flow channels which facilitate rapid circulation of cooling fluid to transport heat away from friction surfaces. Surrounding the clutch assemblies is a heat exchanger to transfer heat directly to the atmosphere. During operation of the clutches, heat removal without residual heat buildup results in thermally stable operating conditions. This operation eliminates the need for torque convertors/fluid couplers and tolerates long duration slippage. The results are a simplified transmission designed for variable speed output and forward/reverse rotation.
