| 摘要 |
A mechanism is provided for securing a paper driving tractor device along a relatively thin elongate member effective in the released condition to permit the tractor to be positioned at will along said elongate member while in the locked condition enabling, positive, secured, engagement of the tractor with said elongate member effective to prevent any movement of the tractor relative to said member, also permitting locking an elongate member repeatedly at the same position without affecting the original characteristics of the elongate member.
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