Electric drive system with differential steering

A method of assembling an electric drive system with an electric motor, comprising:

• providing a driving shaft drivable by the electric motor, the driving shaft having an axis of rotation;
• disposing a differential steering system between the driving shaft and the first and second output members, such that the driving shaft is configured to convey torque from the electric motor to the differential steering system;
• operatively engaging a first planetary gear assembly of the differential steering system between the driving shaft and the first output member and between the driving shaft and the second output member, wherein the first planetary gear assembly has an axis of rotation that substantially aligns with the axis of rotation of the driving shaft;
• operatively engaging a steering motor with the differential steering system to simultaneously adjust the rotational speed of both of the first and second output members to change the rotational speed of one of the first and second output members relative to the other of the first and second output members;
• operatively engaging a second planetary gear assembly of the differential steering system between the first planetary gear assembly and at least one of the first and second output members, the second planetary gear assembly having a sun gear connected to a sun gear of the first planetary gear assembly and the second planetary gear assembly having an axis of rotation that substantially aligns with the axis of rotation of the driving shaft;
• operatively engaging the steering motor with the second planetary gear assembly to modify the rotational speed of the second planetary gear assembly to thereby simultaneously adjust the rotational speed of both of the first and second output members to change the rotational speed of one of the first and second output members relative to the other of the first and second output members;
• operatively engaging a third planetary gear assembly of the differential assembly between the first planetary gear assembly and the second output member, the third planetary gear assembly having a rotational axis that substantially aligns with the rotational axis of the driving shaft, and wherein operatively engaging the second planetary gear assembly includes operatively engaging the second planetary gear assembly between the first planetary gear assembly and the first output member;
• and
• operatively engaging a fourth planetary gear assembly between the electric motor and the first planetary gear assembly, the fourth planetary gear assembly being configured to reduce the rotational speed of the output shaft.

A mobile machine, comprising:

• a first ground engaging device;
• a second ground engaging device;
• a first output member connected to the first ground engaging device;
• a second output member connected to the second ground engaging device;
• an electric motor including a driving shaft having an axis of rotation, the driving shaft being operatively engaged with the first and second output members to rotate the first and second output members;
• a differential steering system operably disposed between the driving shaft and the first and second output members such that the driving shaft conveys torque from the electric motor to the differential steering system, the differential steering system including a first planetary gear assembly operatively engaged between the driving shaft and the first output member and operatively engaged between the driving shaft and the second output member, the first planetary gear assembly having an axis of rotation that substantially aligns with the axis of rotation of the driving shaft;
• a steering motor operatively engaged with the differential steering system and operable to simultaneously adjust the rotational speed of both of the first and second output members to change the rotational speed of one of the first and second output members relative to the other of the first and second output members;
• a second planetary gear assembly operatively engaged between the first planetary gear assembly and the first output member, the second planetary gear assembly having a sun gear connected to a sun gear of the first planetary gear assembly and having an axis of rotation that substantially aligns with the axis of rotation of the driving shaft, wherein the steering motor is operatively engaged with the second planetary gear assembly and operable to modify the rotational speed of the second planetary gear assembly to thereby simultaneously adjust the rotational speed of both of the first and second output members to change the rotational speed of one of the first and second output members relative to the other of the first and second output members;
• a third planetary gear assembly operatively engaged between the first planetary gear assembly and the second output member and configured to have a rotational axis that substantially aligns with the rotational axis of the driving shaft;
• a reaction member connecting sun gears of the second and third planetary gear assemblies, wherein the driving shaft is hollow and the reaction member extends therethrough;
• and
• a fourth planetary gear assembly disposed between the electric motor and the differential steering system, the fourth planetary gear assembly being configured to reduce the rotational speed of the driving shaft.