| 摘要 |
According to a depicted embodiment thereof, the novel earth bit comprises a shank having a threaded end and a bit head centrally bored and threaded to receive a shank. A stack of apertured discs, however, is interposed between the threaded bore or cavity in the bit head and the threaded end of the shank. The discs intimately engage, and bridge between, the shank and bit head threads, and communicate torque therebetween. The bit head cavity has a bearing surface or land upon which the discs are supported, and the shank has an annular shoulder which bears upon the stack and, thus, compressive forces are communicated from the shank to the bit head. The bit head, of the invention, then, comprises the aforesaid bit head, having the stack of discs secured therein by a retainer, for use, in a plural-part earth bit having a threaded shank. |
