Hydraulic automatic transmission bicyle

A hydraulic automatic transmission comprising:

• at least one hydraulic motor which pressurizes fluid contained therein to a motor pressure while increasing and decreasing said motor pressure as external mechanical load exerted onto said hydraulic motor respectively increases and decreases;
• at least one hydraulic pump which pressurizes fluid contained therein using mechanical energy supplied thereto to a pump pressure which is higher than said motor pressure, and to discharge a pump discharging volume of said fluid to said hydraulic motor, wherein said pump discharging volume decreases and increases as said external mechanical load increases and decreases, respectively, whereby said transmission automatically changes gear ratios in response to changes in said external load and in response to changes in said pump discharging volume which is caused by said changes in said external load;
• and
• at least one shift adjustor which manipulates at least one of a maximum external load at which said gear rations change, a minimum external mechanical load at which said gear ratios change, a maximum motor pressure at which said gear ratios change, and a minimum motor pressure at which said gear ratios change.

A hydraulic automatic transmission for automatically changing gear ratios in response to an external mechanical load comprising:

• at least one hydraulic motor which includes a motor driving axis and which discharges a motor discharging volume of fluid at a motor pressure per a revolution of said motor driving axis;
• at least one hydraulic pump which includes an outer cam ring and a pump driving axis, wherein said outer cam ring encompasses therein at least a portion of said pump driving axis which rotates in response to mechanical energy supplied thereto, and wherein said hydraulic pump pressurizes fluid therein to a pump pressure and discharges a pump discharging volume of said pressurized fluid per rotation of said pump driving axis to said hydraulic motor;
• and
• at least one control unit which includes at least one pressure sensor and at least one electrical actuator, wherein said pressure sensor monitors said at least one of said pump pressure and said motor pressure, wherein said actuator moves said outer cam ring in a direction of decreasing said pump discharging volume as said external load increases and which pulls said outer cam ring in another direction of increasing said pump discharging volume as said external load decreases, and wherein said actuator moves said outer cam ring by a distance which is determined by at least one of said pump pressure, said motor pressure, and a difference between said pump and motor pressures,
• whereby said transmission varies a ratio of said pump discharging volume to said motor discharging volume and automatically changes said gear ratios.