Hydro-mechanical transmission with automatic braking capability and method of operation

A hydro-mechanical drive, comprising:

• a mechanical power source having a rotatable output;
• a fluid motor having an output drivingly rotatable by passage of a flow of pressurized fluid from a pressurized fluid source through the motor;
• a planetary gear arrangement including a first rotatable input, a second rotatable input, and a rotatable output, the first rotatable input being connected to the output of the fluid motor so as to be rotatably driven by the motor when the flow of pressurized fluid passes therethrough;
• a first device operable for connecting the second rotatable input of the gear arrangement in rotatably driven relation to the rotatable output of the mechanical power source and for disconnecting the second input therefrom;
• a second device operable when pressurized fluid is received thereby from a pressurized fluid source for connecting the second rotatable input of the gear arrangement to a fixed member for preventing rotation of the second rotatable input;
• and
• a controller operable when a predetermined input signal is received thereby for operating the first device for disconnecting the second rotatable input from the mechanical power source and operating the second device for connecting the second rotatable input to the fixed member, and for preventing the flow of the pressurized fluid through the motor so as to prevent drivingly rotating the output thereof, for preventing driven rotation of the inputs of the planetary gear arrangement by the mechanical power source and the fluid motor.

In a hydro-mechanical transmission for drivingly rotating at least one rotatable element of an agricultural combine, the transmission including a planetary gear arrangement having a rotatable output, a first rotatable input connected to an output of a fluid motor drivingly rotatable by passage of a flow of pressurized fluid therethrough, and a second rotatable input connectable by a device to a rotatable output of a mechanical power source of the combine, and a second device operable when fluid therein is pressurized for connecting the second rotatable input to a fixed member for preventing rotation of the second rotatable input, an improved method for placing the transmission in a neutral operating condition comprising the steps of:

• automatically disconnecting the rotatable output of the mechanical power source from the second rotatable input;
• automatically operating the second device so as to connect the second rotatable input to the fixed member to prevent rotation of the second rotatable input;
• and
• automatically preventing the passage of a flow of pressurized fluid through the fluid motor so as to prevent the driving rotation thereof when the second rotatable input is disconnected from the rotatable output of the mechanical power source and is connected to the fixed member, such that driving rotation of the transmission is prevented.