Transmission System For A Propulsion System

A method of operating a transmission system for a propulsion system, the propulsion system comprising at least one power unit, a power transfer system and at least one propulsion element, the transmission system comprising:

• a summation transmission configured to receive power from the at least one power unit and/or power transfer system;
• a propulsion output transmission comprising a first propulsion output shaft and configured to receive power from the summation transmission and direct the power to the at least one propulsion element;
• and
• a power transfer transmission operably connected to the summation transmission and configured to transfer power between the summation transmission and the power transfer system, the power transfer transmission comprising a first power transfer shaft and a power transfer coupler,
• wherein the method comprises:
• receiving power at the power transfer transmission from the power transfer system;
• determining whether to engage the power transfer coupler;
• and
• engaging the power transfer coupler such that the first power transfer shaft is operably connected to the first propulsion output shaft such that power is transferred directly from the power transfer system to the propulsion output transmission.

A method of operating a transmission system for a propulsion system for a marine vessel, the propulsion system comprising at least one power unit having a power unit output shaft, a power transfer system and at least one propulsion element, the transmission system comprising:

• a summation transmission configured to receive power from the at least one power unit and/or power transfer system and provide a power output to the at least one propulsion element;
• a power unit transmission mounted to the at least one power unit output shaft to receive a rotational input therefrom and comprising at least one coupler configured to selectively direct power from the rotational input to the summation transmission and/or power transfer system,
• the method comprising:
• receiving the rotational input at the power unit transmission from the at least one power unit output shaft;
• operating the at least one coupler to direct the rotational input to the summation transmission in a first rotational direction or a second rotational direction.

A method of operating a propulsion apparatus, the propulsion apparatus comprising:

• at least two propulsion systems, each comprising:
• a transmission system configured to provide a power output to at least one propulsion element;
• at least one first energy conversion machine;
• at least one primary power unit operable to selectively drive the transmission system and/or the at least one first energy conversion machine;
• and
• at least one second energy conversion machine operable to selectively drive or be driven by the transmission system,
• at least one secondary power unit configured to selectively provide power to at least one power generator;
• and
• a power transfer system for transferring power between the first and second energy conversion machines and at least one power generator;
• wherein the method comprises:
• receiving a demand to drive the at least one propulsion element at a system output speed;
• operating at least one primary and/or secondary power unit to provide power to the at least one propulsion element via the power transfer system and/or transmission system.