PURPOSE: To normally carry out reverse drive of a fan in the reverse drive of the fan by energizing a switching member onto a normal rotation position side, operating the switching member to a reverse rotation position against the energizing force to be pressed and energized onto a transmission belt so as to maintain tension of the transmission belt.
CONSTITUTION: When a switching member 16 is operated in a normal rotation position, tension of a transmission belt 14 is maintained by two of a normal rotation pulley 17 and a tension pulley 15, so that the tension of the transmission belt 14 is surely maintained without affected by vibration even when the transmission belt 14 is vibrated according to the rotation. Inversely, when the switching member 16 is operated by an operation means 26, the tension pulley 15 in another position is pressed onto a transmission belt 14 while the transmission belt 14 is pressed by a reverse rotation pulley 18, even though operation quantity of the operation means 26 to the reverse rotation position B is fixed. In this way, in the reverse rotation position B, the tension pulley 15 follows up and the tension of the transmission belt 14 can be maintained without affected by the vibration, even though the transmission belt 14 is vibrated according to the rotation.
IKEDA FUTOSHI
YAMAGATA KOJI
HIRATA KAZUYOSHI
HAYASHI SHIGEKI
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