Abstract: An energy converter transmission uses a throughshaft clutch and a through-shaft energy converter for transfer of energy to and from a shaft. The energy converter includes a housing and a rotor mounted to a hollow coupling shaft. The energy converter can be an hydraulic, a pneumatic or an electric energy converter. A first clutch element is also mounted to the coupling shaft. A second clutch element is mounted to the main drive shaft which passes through the hollow coupling shaft. Actuation of the clutch engages the clutch elements to couple the main drive shaft to the rotor via the clutch and coupling shaft.