AGGREGATE TO DRILL BIG DIAMETER BOREHOLES Russian patent published in 1995 - IPC

FIELD: drilling equipment. SUBSTANCE: aggregate has traverse with central driving switch, additional weights and three bottom hole engines with gear modules, provided with equal outer diameter drill bits. Gear ratio of modules is determined by dependance U_m=2R_m/R_e·U_e with U_m - gear ratio of middle bottom hole engine gear module; U_e - gear ratio of extreme bottom hole engine gear module; R_m - space from central axis of aggregate to axis of middle bottom hole engine; R_e - space from central axis of aggregate to axis of extreme bottom hole engine. Torque from shafts of driving engines, using gear modules is transferred to drill bits and is redistributed in accordance with distance of drilling bit from longitudinal axis of drill. EFFECT: increase of drilling productivity. 6 dwg, 1 tbl