| 摘要 |
An improved drilling bit has a cone shaped cutter 22 rotatably mounted on a leg 16 by way of a central journal 18 and an annular journal 20. The annular journal is axially coextensive with the central journal. The cutter has outer collar 26 and inner collar 28 which interfit with the journals to provide a large surface area for roller bearings 30, 36 and 42. Additionally, the cutter may have a post 68 within cavity 70 on the terminal and of the central journal 18 so that roller bearings 74 can be provided to further increase the area of roller bearings handling radial loads. This increases the lifetime of the bit assembly. Ball bearings 50, 52, 66 and 72 are provided to handle axial loads, and ball bearings 54 are provided to retain the cutter on leg 16.
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