| 摘要 |
1,060,943. Boring earth &c. H. VON RAUTENKRANZ. Jan. 14, 1965 [July 9, 1964], No. 1614/65. Heading E1F. A boring grab supported by a single cable 3 has a locking device 9, 10 for the blades 1 arranged so that the bottom of the hole may be subjected to impacts from the opened blades without closure thereof. The grab is raised and lowered, and the blades are opened and closed by longitudinal movements of the cable, the device ensuring that the blades close after a predetermined number of impacts. The number of impacts may be varied by the substitution of an interchangeable part. Closure of the blades permits flap valves 6 to close so that semi-liquid spoil may be trapped in a container 4. |
