| 摘要 |
A device including a drill bit is disclosed. The bit preferably comprises lug members, joined by a support member, each lug member includes a through hole, bearings rotatably mounted on the lug members which bearings support cutter members, a sleeve with lubricant mounted upon the support member, a central channel within the sleeve whose lower end can be closed or opened with a reciprocating valve-plate, an annular piston snug-fitting between the sidewalls of sleeve and central channel, which piston has a discharge valve outletting the lubricant through the piston, a spring disposed in the sleeve, rods mounted in the sleeve and inserted through the holes, lubrication channels arranged in the lug members and communicating the lower portion of sleeve with the bearings for lubrication thereof. The rods are coupled to the piston and the valve-plate. Embodiments include shafts supporting the bearings. Some shafts are hollow and have a coolant system. |
