| 摘要 |
A movable carriage which is connected to a smooth actuating rod for movement therewith to a desired position where it is locked to a fixed bridge permitting the actuating rod to move with respect thereto. The movable carriage or head is clamped to the actuating rod with a continual friction force which is easily overcome by the force with which the carriage is locked to the fixed bridge. The actuating rod is movable back and forth along its longitudinal axis by manual or automatic positioning apparatus. By successive moving and locking operations for the carriage, the carriage can be moved along the entire bridge while the movement of the actuating rod is more limited. The actuating rod can be a smooth metallic rod with the carriages permanently clamped thereto with a determinable friction force, alternately the carriage can be clamped to the actuating rod until the carriage is clamped to the fixed bridge. A drive motor is used for moving the actuating rod back and forth. A manual back-up is provided for manually moving the actuating rod. When more than one carriage is utilized, adjacent carriages can be moved close together. That is, movement of the carriages is not restricted to selected zones.
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