Control system and method for braking a hydrostatic drive machine

A method of braking a hydrostatic drive machine, comprising:

• reducing a displacement of a pump of a hydrostatic drive system to a non-zero displacement;
• increasing a displacement of a motor of the hydrostatic drive system to a displacement that is less than a maximum displacement;
• accelerating all engine of the hydrostatic drive system toward a desired engine speed range;
• and
• reducing a speed of a flywheel that mechanically couples the engine and the pump using a friction brake if a speed of the engine exceeds the desired engine speed range.

A hydrostatic drive machine, comprising:

• an internal combustion engine;
• at least one variable displacement pump mechanically coupled to the internal combustion engine;
• at least one variable displacement motor fluidly coupled to the at least one variable displacement pump;
• at least one ground engaging element mechanically coupled to the at least one variable displacement motor;
• and
• an electronic controller in communication with the at least one variable displacement pump and the at least one variable displacement motor, wherein the electronic controller is configured to receive a machine braking request, identify a current motor displacement, issue a pump displacement command to reduce a displacement of the at least one variable displacement pump to a non-zero displacement and simultaneously issue a motor displacement command to set a displacement of the at least one variable displacement motor to adjust a motor flow rate toward a pump flow rate while the current motor displacement is less than a maximum displacement, and issue a pump displacement command to set the pump displacement to adjust the pump flow rate toward the motor flow rate while the motor displacement is at the maximum displacement.

A hydrostatic drive machine, comprising;

• an internal combustion engine;
• at least one variable displacement pump mechanically coupled to the internal combustion engine;
• at least one variable displacement motor fluidly coupled to the at least one variable displacement pump;
• at least one ground engaging element mechanically coupled to the at least one variable displacement motor;
• an electronic controller in communication with the at least one variable displacement pump and the at least one variable displacement motor, wherein the electronic controller is configured to receive a machine braking request, issue a pump displacement command to reduce a displacement of the at least one variable displacement pump to a non-zero displacement in response to the machine braking request, and issue a motor displacement command to increase a displacement of the at least one variable displacement motor to a displacement that is less than a maximum displacement in response to the machine braking request, wherein the pump displacement command and the motor displacement command are selected to accelerate the internal combustion engine toward a desired engine speed range;
• and
• a friction brake actuable to slow rotation of a flywheel that mechanically couples the internal combustion engine and the at least one variable displacement pump.

A non-transitory computer usable storage medium having computer readable program code thereon for braking a hydrostatic drive machine, comprising:

• computer readable program code for receiving a machine braking request;
• computer readable program code for identifying a current motor displacement;
• computer readable program code for generating a pump displacement command for reducing a displacement of a variable displacement pump to a non-zero displacement and simultaneously generating a motor displacement command to set a displacement of a variable displacement motor to adjust a motor flow rate toward a pump flow rate while the current motor displacement is less than a maximum displacement;
• and
• computer readable program code for generating the pump displacement command to set the pump displacement to adjust the pump flow rate toward the motor flow rate while the motor displacement is at the maximum displacement.