Patent attributes
A rotation direction detection apparatus is configured to detect the direction of rotation of a pulley that is rotatably mounted to a chain guide, and includes a rotation sensor, a detection element and a shielding mechanism. The rotation sensor is fixed to the chain guide. The detection element is mounted to the pulley such that it can be detected by the rotation sensor. The shielding mechanism has a shielding arm that is mounted to move between a shielding position where the rotation sensor cannot detect the detection element and a detection position where the rotation sensor can detect the detection element. The shielding mechanism has a linking member that moves the shielding arm in tandem with the rotation of the pulley in first or second rotational directions. The shielding mechanism has a positioning protrusion that positions the shielding arm at either the shielding position or the detection position.
