Importance

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Abstract

A lifting device for down hole tubulars is used with an earth drilling machine of the type having a boom for moving a down hole tubular from a horizontal position at an intermediate level to a raised position aligned with a drilling axis, and a tubular holding device for holding a down hole tubular horizontally at a lower level, beneath the intermediate level. The lifting device includes first and second spaced, parallel tracks oriented to extend substantially from the lower level substantially to the upper level and first and second dolleys, each guided for movement along a respective one of the tracks and configured to retain the down hole tubular. The dolleys are moved between the lower and intermediate levels by an actuator which is connected to both of the dolleys by a mechanical linkage which includes tension members. This mechanical linkage positively synchronizes movement of the dolleys along the tracks to maintain the tubular horizontal as it is moved between the lower and intermediate levels.

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First Claim