EARTH BORING BIT WITH COOLED JOURNAL BEARING

摘要

An earth boring bit has a friction or journal bearing with features that allow cooling fluid to be circulated near the bearing. The bit is of the type having rotatable cutters carried by depending bearing pins. A bushing is stationarily mounted on the bearing pin, with the bushing's inner surface in contact with the outer surface of the bearing pin. One of the surfaces has a plurality of grooves that extend at least partially around the bearing pin. Passages are formed in the bearing pin and bit for circulating cooling fluid through the grooves. The cutter is mounted on the bushing in rotating and sliding contact to form a journal bearing.