WORKING TOOL OF HOLE DIGGER Russian patent published in 1995 - IPC

FIELD: mechanical engineering. SUBSTANCE: working tool has central tube 1 with flat bit 2 in its bottom part and flange 3 in its top part. It also has an auger surface with flights cyclically variable in height. Ripping teeth 6 are located where the height of the flights is maximum, and cutting teeth 5 are located at the lower ends of flights of auger 4. The flight maximum height is twice its minimum, and it is equal to spacings between teeth 6. The lower ends of the auger flights are provided with hard-faced cutting teeth 5 inclined 40-45 deg relative to the horizontal plane. EFFECT: higher operational reliability. 2 cl, 2 dwg