| 摘要 |
949,857. Boring earth. HUGHES TOOL CO. May 25, 1961 [Jan. 3, 1961], No. 18978/61. Heading E1F. [Also in Division F2] An earth boring rotary drill bit, Fig. 1, comprises a conical cutter 7 rotatably mounted by means of ball and roller bearings 8, 9 on a pin 6 integral with a leg 4 of the bit head 2. The balls 9 are loaded in their raceway througha bore 11 which is plugged at 15 after insertion of the balls. Lubricant for the bearings is supplied from a reservoir 17 which communicates with the bore 11 by means of a passage 18. The lower end of the reservoir 17 is provided with a collapsible rubber diaphragm 20 which serves to transmit pressure from the drilling fluid to the lubricant 16. The upper end of the reservoir is closed by a cap 21 through which lubricant is introduced after removal of a plug 23. Sealing of the bearings is effected by an axially resilient seal ring 31, Fig. 2, which is a force fit on the pin 6 and which is compressed between annular faces 36, 37 respectively on the cutter 7 and the leg 4. The ring is provided with axial protuberances 34, 35, the area of contact of the protuberance 34 with the face 37 being greater than that of the protuberance 35 with the face 36 so that the area of the end face of the ring exposed to lubricant pressure is greater than that exposed to drilling fluid pressure. The difference in these areas helps to maintain sealing contact when the drilling fluid pressure exceeds the lubricant pressure which fluctuates as a result of axial and wobbling movements of the cutter in operation. A gap 29 between the ring 31 and the wall 45 of a counterforce in the cutter 7 permits radial movement of the cutter in operation.
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