| 摘要 |
A variable ratio drive mechanism which operates to adjust the path of an endless drive belt in response to a remotely located control input. A plurality of circumferentially spaced sheave segments are respectively mounted in a plurality of radially extending elongated tracks with opposed tooth-like formations therein. Each sheave segment includes cam/bearing means with multiple camming surfaces and opposed engagement blocks intermediate the cam/bearing means and the tooth-like formations. The engagement blocks are mutually slidably engaged but spring-biased into engagement with the tooth-like formations to thereby detent the sheave segment against radial movement. Each sheave segment has a bearing surface which is engaged by the drive belt when the drive mechanism traverses through a predetermined arc of rotation but is disengaged from the drive belt when outside the predetermined arc of rotation. When a sheave segment is moved radially by a shift cam on the drive mechanism the camming surfaces on the cam bearing means are engaged by and slide along follower surfaces on the engagement blocks until the engagement blocks are disengaged from the tooth-like formations and are caused to move up one or more notches, as necessary. At the new radially disposed location, the engagement blocks are again spring biased into engagement with the tooth-like formations to resume detenting the sheave segment against radial movement.
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