| 摘要 |
1355447 Boring earth &c HEATH & SHERWOOD DRILLING Ltd 3 Jan 1972 [4 Jan 1971] 89/72 Heading E1F Boring apparatus comprises a derrick 10 having a travelling block 28 supporting a drill string 30, a drill head 31 having a chuck 53, hydraulic jacks 66 for reciprocating the chuck, a hydraulic motor 60 for rotating the chuck, and I.C. motors 34, 35 driving pumps 36, 43 supplying the Jacks 66, the motor 60 and the hoisting winch 32. The pumps 36, 43 selectively provide power for the motor 60 or the hoisting winch motor 79. A solenoid valve 99a operated by excessive pump pressure raises the string to prevent damage to the bit. A winch brake 82, power tongs 92 and a wireline winch 33 are provided. The drill head is slidable to the side of the string to facilitate work on the string. After a short hole has been bored using the chuck, the swivel 30a is replaced by a power swivel which is used to extend the hole. The derrick comprises two members 11 each comprising hinged portions 12, 13 and each portion 12 being supported by two braces 15. |
