A uni-directional drive gear includes a plurality of teeth each pivotably mounted on a mounting seat to be turned between driving and idle positions so as to permit the gear to rotate in a uni-rotational direction. A gear transmission device having the uni-directional drive gear can be configured to perform different transmissions to suit a wide variety of requirements.

A uni-directional drive gear includes a plurality of teeth each pivotably mounted on a mounting seat to be turned between driving and idle positions so as to permit the gear to rotate in a uni-rotational direction. A gear transmission device having the uni-directional drive gear can be configured to perform different transmissions to suit a wide variety of requirements.

A uni-directional drive gear includes a plurality of teeth each pivotably mounted on a mounting seat to be turned between driving and idle positions so as to permit the gear to rotate in a uni-rotational direction. A gear transmission device having the uni-directional drive gear can be configured to perform different transmissions to suit a wide variety of requirements.

A uni-directional drive gear includes a plurality of teeth each pivotably mounted on a mounting seat to be turned between driving and idle positions so as to permit the gear to rotate in a uni-rotational direction. A gear transmission device having the uni-directional drive gear can be configured to perform different transmissions to suit a wide variety of requirements.

To provide a drive force transmission device that is capable of transmitting elastic energy of an elastic member to an output shaft with a simpler structure than the structure of the related art. A drive force transmission device includes a first shaft (input shaft), and a second shaft (a crankshaft, a crank disc, an intermediate shaft). A force is applied to the second shaft in a predetermined direction of rotation and in a direction opposite to the direction of rotation. The force varies in strength in association with the rotation. The first shaft is connected to the second shaft, and transmission of a drive force of the first shaft to the second shaft is enabled.

To provide a drive force transmission device that is capable of transmitting elastic energy of an elastic member to an output shaft with a simpler structure than the structure of the related art. A drive force transmission device includes a first shaft (input shaft), and a second shaft (a crankshaft, a crank disc, an intermediate shaft). A force is applied to the second shaft in a predetermined direction of rotation and in a direction opposite to the direction of rotation. The force varies in strength in association with the rotation. The first shaft is connected to the second shaft, and transmission of a drive force of the first shaft to the second shaft is enabled.

A gear train includes at least four gears sequentially engaged, multiple links configured to support the rotation shafts of the gears, and pins configured to fix the rotation shafts of the gears to the link, wherein the pins are installed such that, among the rotation shafts of the gears, two non-adjacent rotation shafts have both ends fixed to the link and one of adjacent rotation shafts has only one end fixed to the link.

A gear train includes at least four gears sequentially engaged, multiple links configured to support the rotation shafts of the gears, and pins configured to fix the rotation shafts of the gears to the link, wherein the pins are installed such that, among the rotation shafts of the gears, two non-adjacent rotation shafts have both ends fixed to the link and one of adjacent rotation shafts has only one end fixed to the link.