| 摘要 |
A drilling rig for boring holes in the door of a combination safe includes a bracket for clamping the rig to the door of the safe, an upstanding U-shaped drill frame carried by the clamping bracket and a bearing assembly including a drill shaft journaled for rotation in an elongate outer barrel having internal thrust bearings. Axial movement of the entire bearing assembly is effected by rotating the barrel against mating threads carried by the drill frame. Thrust loads are distributed from the bearing assembly, through the drill frame and clamping bracket to the safe. A chuck is provided for fixing a drill bit to the inner end of the drill shaft. This insulates the motor used to rotate the drill shaft from all thrust loads.
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