| 摘要 |
This invention relates to a power transmission device for coupling an input or driving shaft with an output or driven shaft. The power transmission device permits the output shaft to be engaged or disengaged from the input shaft. The device comprises a first side gear mechanically connected to the output shaft and a second side gear mechanically coupled to a brake which can decrease the rate of rotation of the second side gear to zero. In one embodiment, the gear ratio between the first side gear and the second side gear is greater than one. The device further comprises carried gears rotatably engageably coupled with the first and second side gears such that the carried gears rotate between and around the first and second side gears. The carried gears are carried by a gear carrier. The carried gears are mechanically connected to the gear carrier such that rotation of the input shaft on its axis causes the gear carrier to carry the carried gears around the first and second side gears. In operation, when the brake does not resist the rotation of the second side gear, the output shaft is disengaged from the input shaft. When the brake resists the rotation of the second side gear, the output shaft becomes engaged to the input shaft and rotates at a greater rate of rotation than the input shaft. In another embodiment, the invention further comprises a lock-up clutch means which couples the second side gear to the gear carrier so that the output shaft will rotate at the same rate of rotation as the input shaft regardless of the gear ratio of the first side gear to the second side gear.
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