Speed reducer

A speed reducer comprising:

• an input shaft;
• an output shaft;
• and
• a gear assembly coupled to the input shaft and comprising a housing, an external gear, and at least two internal gears, the external gear located within the housing, the at least two internal gears connected inside the external gear and comprising a first internal gear and a second internal gear, one of the sides of the first internal gear rotatably coupled to the input shaft, one of the sides of the second internal gear coupled to a connecting column of the output shaft;
• wherein the second internal gear comprises a connector extending from the one of the sides of the second internal gear toward the connecting column of the output shaft, the connector is coupled to the connecting column;
• wherein the input shaft is an offset shaft;
• wherein the input shaft drives the at least two internal gears to maintain engagement with the external gear;
• and
• wherein the connecting column maintains transmission between the output shaft and the at least two internal gears.