| 摘要 |
A rotary earth boring drill is provided having a body structure with a plurality of depending cutter supporting legs having integral spindles extending transversely therefrom. Rotary cutter cone elements are supported by split bushings, roller bearings or a combination of the same, on appropriate bearing surfaces defined by the integral spindles. The bushings and cutter cones define mating tapered surfaces having an interference fit that secures the bushings and cutter cone in nonrotatable assembly. Circular locking elements are provided in locking grooves that are defined cooperatively by the bushings and cutter cones. End portions of the bushings extend axially beyond a planar surface defining one extremity of the cutter cone and establishes rotatable sealing engagement with an opposed planar surface defined by the depending leg structure of the bit. This rotatable seal prevents drill cuttings, dust and other debris from entering the bearing support of the cutter cone. A circular resilient seal may also be supported by the cutter cone and may also have rotatable sealing engagement with the planar surface of the depending leg, thus providing additional sealing and protection of the bushings and bearings. |
