Dual pinion and ring architecture for gear systems

A gear system comprising:

• a housing;
• and
• a gear set in the housing, the gear set including:
• a shaft extending in the housing, the shaft including a base shaft section and an eccentric section, wherein the shaft is rotatable about an axis, wherein the base shaft section is centered on the axis, and wherein the eccentric section has a center that is offset from the axis, wherein the center circles around the axis when the shaft rotates;
• a pinion gear unit mounted on the eccentric section, the pinion gear unit having a first pinion gear with a first set of gear teeth and a second pinion gear with a second set of gear teeth;
• a first ring gear engaging with the first set of gear teeth, the first ring gear fixed to the housing;
• a second ring gear engaging with the second set of gear teeth;
• a counterweight extending from the shaft to balance the eccentric section, wherein the counterweight has a head with a shape that is T-shaped and that is disposed axially in-line with the first ring gear with a radially outer portion of the head being axially adjacent the first ring gear, wherein the shape is configured to be tuned for balancing the eccentric section;
• and
• a rotatable member fixed to the second ring gear,
• wherein the gear system is configured so that rotation of the shaft at a first speed effects rotation of the rotatable member at a second speed through the shaft, the pinion gear unit, the first ring gear and the second ring gear.

A gear system for a vehicle having a prime mover and an axle, the gear system comprising:

• a housing fixed to the vehicle;
• and
• a gear set in the housing, the gear set including:
• a shaft coupled with the prime mover and extending in the housing, the shaft including a base shaft section and an eccentric section, wherein the shaft is rotatable about an axis, wherein the base shaft section is centered on the axis, and wherein the eccentric section has a center that is offset from the axis, wherein the center circles around the axis when the shaft rotates;
• a pinion gear unit mounted on the eccentric section, the pinion gear unit having a first pinion gear with a first set of gear teeth and a second pinion gear with a second set of gear teeth;
• a first ring gear engaging with the first set of gear teeth, the first ring gear fixed to the housing;
• a second ring gear engaging with the second set of gear teeth;
• a counterweight extending from the shaft to balance the eccentric section, wherein the counterweight has a head with a shape that is T-shaped and that is disposed axially in-line with the first ring gear with a radially outer portion of the head being axially adjacent the first ring gear, wherein the shape is configured to be tuned for balancing the eccentric section;
• and
• a rotatable member coupled with the axle and fixed to the second ring gear,
• wherein the eccentric section is configured with openings to reduce weight, wherein the openings extend completely through the eccentric section in a direction parallel to the axis, wherein the eccentric section has a high side and a low side, wherein the openings include a first opening that is centered on the high side and that is larger than others of the openings,
• wherein the gear system is configured so that rotation of the shaft by the prime mover at a first speed effects rotation of the rotatable member and the axle at a second speed through the shaft, the pinion gear unit, the first ring gear and the second ring gear,
• wherein the first pinion gear and the second pinion gear are configured to rotate and to orbit about the axis together on the eccentric section.