POWER TRANSMISSION DEVICE

PROBLEM TO BE SOLVED: To provide a power transmission device capable of easily changing a shift stage between two shift stages and rapidly completing the same.SOLUTION: Rotational frequencies of first to third rotary elements are aligned on a single straight line in this order in a common line diagram. The third rotary element is connected to a driven portion, and first rotation power for rotating the first rotary element in a first prescribed rotating direction, and second rotation power for rotating the first rotary element in a second prescribed rotating direction opposite to the first prescribed rotating direction, are input to the first rotary element connected to a power source, from the power source. First switching means prevents rotation of the second rotary element to the first prescribed rotating direction during generation of the first rotation power, and permits the rotation of the second rotary element to a second prescribed rotating direction during generation of the second rotation power. Second switching means prevents the rotational frequency of the first rotary element from being over the rotational frequency of the second rotary element during generation of the second rotation power, and permits the rotational frequency of the first rotary element to be over the rotational frequency of the second rotary element when the second rotation power is not generated.SELECTED DRAWING: Figure 1 【課題】２つの変速段の間での変速段の変更を、容易に行えるとともに、迅速に完了させることができる動力伝達装置を提供する。【解決手段】第１〜第３回転要素の回転数が共線図において単一の直線上にこの順で並ぶ。第３回転要素が被駆動部に連結され、動力源に連結された第１回転要素には、第１回転要素を第１所定回転方向に回転させる第１回転動力と、第１所定回転方向と逆方向の第２所定回転方向に回転させる第２回転動力が、動力源から入力される。第１切替手段が、第１回転動力の発生中に第１所定回転方向への第２回転要素の回転を阻止し、第２回転動力の発生中に第２所定回転方向への第２回転要素の回転を許容する。第２切替手段が、第２回転動力の発生中に第１回転要素の回転数が第２回転要素の回転数を上回ることを阻止するとともに、第２回転動力が発生していないときに第１回転要素の回転数が第２回転要素の回転数を上回ることを許容する。【選択図】図１