| 摘要 |
A linear actuator for selectively moving a carriage relative to a support frame along a predefined linear path. The linear actuator includes a drive shaft having a cylindrical surface, means for rotatably mounting the drive shaft to the frame for rotation of the drive shaft about the axis of the cylindrical surface, means coupled to the drive shaft for rotating the drive shaft about such axis, a carriage to be driven along the predefined linear path between an inactive position and at least one active position, a roller, means for mounting the roller to the carriage with the roller being rotatable about a first axis and pivotable about a second axis perpendicular to the first axis, means for mounting the carriage to the support frame with the carriage being movable relative to the support frame along the predefined linear path between the inactive and at least one active position and with the roller being in frictional engagement with the cylindrical surface of the drive shaft whereby the roller is caused to rotate about its axis by rotation of the drive shaft when the first axis is parallel to the axis of the drive shaft and is additionally caused to move along the predefined linear path during rotation of the drive shaft when the first axis is oblique to the axis of the drive shaft, and means for controllably pivoting the roller about its second axis to control movement of the roller and thus the carriage along the predefined linear path. The means for mounting the carriage to the support frame includes means for biasing the roller against the cylindrical surface with a first level of force when the carriage is at an active position and with a second level of force when the carriage is at its inactive position.
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