F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
F16B39/00—Locking of screws, bolts or nuts
F16B39/02—Locking of screws, bolts or nuts in which the locking takes place after screwing down
F16B39/12—Locking of screws, bolts or nuts in which the locking takes place after screwing down by means of locknuts
F16B39/14—Locking of screws, bolts or nuts in which the locking takes place after screwing down by means of locknuts made of thin sheet material or formed as spring-washers
E—FIXED CONSTRUCTIONS
E21—EARTH OR ROCK DRILLING; MINING
E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
E21B10/00—Drill bits
E21B10/08—Roller bits
E21B10/20—Roller bits characterised by detachable or adjustable parts, e.g. legs or axles