Reduction gear

A reduction gear comprising:

• a first planetary gear set reducing an output rotation speed of a power source, the first planetary gear set possessing a first ring gear,
• a counter gear set reducing an output rotation speed of the first planetary gear set, and
• a second planetary gear set reducing an output rotation speed of the counter gear set, the second planetary gear set possessing a second ring gear, and
• a case covering an outer circumference of the first planetary gear set and an outer circumference of the second planetary gear set, wherein
• an output shaft and an input shaft of the first planetary gear set are arranged coaxially,
• an output shaft and an input shaft of the second planetary gear set are arranged coaxially,
• the output shaft and the input shaft of the first planetary gear set are arranged in parallel with the output shaft and the input shaft of the second planetary gear set,
• a center axis of an input shaft of the counter gear set is common to a center axis of the output shaft of the first planetary gear set,
• a center axis of an output shaft of the counter gear set is common to a center axis of the input shaft of the second planetary gear set,
• an output gear of the counter gear set and a wheel shaft are coaxial, and
• the first ring gear and the second ring gear are rotationally fixed relative to the case.

A reduction gear comprising:

• a first planetary gear set reducing an output rotation speed of a power source, the first planetary gear set possessing a first ring gear;
• a counter gear set reducing an output rotation speed of the first planetary gear set;
• and
• a second planetary gear set reducing an output rotation speed of the counter gear set, the second planetary gear set possessing a second ring gear;
• and
• a case covering an outer circumference of the first planetary gear set and an outer circumference of the second planetary gear set, wherein
• an output shaft and an input shaft coaxially disposed in the first planetary gear set are arranged in parallel with an output shaft and an input shaft coaxially disposed in the second planetary gear set,
• an input shaft of the counter gear set is common to the output shaft of the first planetary gear set,
• an output shaft of the counter gear set is common to the input shaft of the second planetary gear set, and
• an output gear of the counter gear set and a wheel shaft are arranged coaxially;
• the first ring gear and the second ring gear are mounted on the case;
• the first ring gear and the second ring gear are rotationally fixed relative to the case;
• and wherein all or a part of the first planetary gear set and the second planetary gear set are arranged on a same plane perpendicular to an axis of the first planetary gear set;
• said reduction gear further comprising:
• a first bearing rotationally supporting a part of gears of the counter gear set, said first bearing being arranged in at least partially of an inner circumferential area of a gear width of said part of the gears;
• and
• a second bearing rotationally supporting a carrier of the second planetary gear set and being arranged at an inner circumferential area of the carrier.