| 摘要 |
Apparatus for positioning a power tong (50) at a desired location with respe ct to the distance above the rig floor, and with respect to the center of the r ig floor. A pedestal (70) is secured to the structure of the rig. An upright member (75) is mounted to the upper end of the pedestal (70), with a bearing (70a) disposed between the upright member (75) and the pedestal (70), the bearing permitting the upright member to rotate around a vertical axis when moved by a powered ring gear assembly (70c). A telescoping boom (60) is rotatably mounted on the upright member (75), and one end thereof extends ov er the central part of the rig floor. Power tongs (50) attached to the boom may thereby be positioned at desired positions with respect to the rig floor. Controls (50a, 70b) mounted on the power tongs (50) and/or on the upright member (75) permit control of the rotation of the boom (60), the upright member (75), ang the power tong (50).
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