| 摘要 |
A tension providing mechanism including two shafts, one having an external screw and the other having an internal screw, the shafts being connected by engaging the screwed portions with each other. One of the shafts is supported for axial translation without rotation, and the other shaft is supported for rotation and is restrained from axial sliding. The rotatable shaft includes a torsion spring for applying spring torque in a direction to cause the other shaft to extend in an axial direction against a member, such as a drive chain, in order to increase the tension thereof. A locking mechanism is provided for constraining movement of the rotatable shaft, the locking mechanism being in the form of a lever having one end removably engaged with a split groove provided in the end of the shaft, the other end of the locking mechanism being latched to a projection formed on the case in which the tension providing mechanism is housed.
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