DROP IMPACT ABSORBING DEVICE FOR KELLY-BAR

摘要

PROBLEM TO BE SOLVED: To provide a drop impact absorbing device for a kelly-bar capable of reducing impact while preventing the occurrence of contact sound caused by the mutual collision of steel in the fall of the kelly-bar. SOLUTION: The upper face of a rotating part 4a of a kelly-bar driving device 4 for rotationally driving the extensible kelly-bar of a vertical hole excavator while inserting it through is provided with a cushioning material 11 receiving a flange-type stopper 14 at the upper end of an outer kelly-bar 5b. The upper face of the cushioning material 11 is provided with a cushioning material mounting ring 12 made of a steel plate. The lower face of the stopper 14 or the upper face of the ring 12 is provided with a cushioning material 15 for absorbing impulsive sound. COPYRIGHT: (C)2005,JPO&NCIPI