GB844296A - Improvements in earth digging appliances - Google Patents

Abstract

844,296. Borehole apparatus. EDWARDS BUILDING SERVICES PTY. Ltd. Nov. 21, 1958 [Dec. 6, 1957], No. 37615/58. Class 85. A bucket adapted to be attached to an auger shaft and lowered into a hole cut by a standard auger has extending cutters which enlarge the bottom of the hole. The bucket 10 has a boss 12, with a square hole in it, mounted on the beams 11. Sliding in the boss is a square shaft 14, the movement of which is limited by a pin 19 running in slots 20 in the bush. The shaft 14 has an extension of circular cross-section which reaches nearly to the bottom of the bucket, is contained within a hollow shaft 15 which extends to the bottom of the bucket, and is supported at its upper end by a bearing 16. The shaft 15 is free to rotate relative to the bucket, but vertical movement is prevented by two collars 18. The bucket is supported by the pin 19 while being lowered into a hole but when it strikes the bottom of the hole, the shaft 14 moves down and projecting pins 21 move along spiral slots 22 in the hollow shaft 15 and turn it. As the shaft 15 turns a cross-beam 23 secured to it operates two links 25 which extend the cutters 26. In a modification (Fig. 6) the linkage for the cutters comprises a square shaft 114 which can move vertically, but not rotate, relative to the bucket 110. When the bucket strikes the bottom of the hole the links 125 move from the dotted line position to the full line position and extend the cutters.