| 摘要 |
A sleeve attachable to a tool to be lowered into an uncased well bore has at least one roller mechanism connected in longitudinal relationship therewith so that the roller mechanism is disposed beneath the tool as the tool is lowered into the well bore. The roller mechanism has a plurality of radially extending protuberances obliquely disposed around the periphery of the roller mechanism. The protuberances grippingly engage the wall of the well bore so that the roller mechanism rotates to roll the tool off of any ledges encountered along the wall. The oblique disposition of the protuberances also imparts a rotational kick to the tool to move it away from the wall into the bore for permitting further lowering of the tool into the well bore.
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