| 摘要 |
A camming device (10) comprises a stem (12), a spindle (16) mounted on the stem, at least two cam members (24,26) adapted to engage the walls of a crack or hole by their cam profiles pivotally mounted on the spindle and adapted for opposite pivotal movement from a closed position to an open position, means (28,30) to apply a force to each cam member to urge it to its open position, and means for pivoting the cams to the closed position, characterised in that the stem is mounted directly to the spindle.
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