| 摘要 |
966,286. Boring earth &c. INGERSOLLRAND CO. April 4, 1963 [April 9, 1962], No. 13371/63. Heading E1F. In a down-the-hole drill comprising a body 1, reciprocable bits 4, 5 at one end of the body, and a head 9 at the other end of the body adapted to be attached to a rotatable hollow drill rod 28, the head has passages 29, 30 for the supply of pressure fluid from the rod to this actuating mechanisms of the bits. The mechanisms are housed in casings 2, 3 which rotate with the head, and the bits 5 may be turned and fixed in different positions in their casings to compensate for bit wear. |
