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1. (WO1997014870) SHOCK-ABSORBING MECHANISM FOR HYDRAULIC HAMMERING DEVICE

Pub. No.:    WO/1997/014870    International Application No.:    PCT/JP1996/002996
Publication Date: Apr 24, 1997 International Filing Date: Oct 16, 1996
IPC: B25D 9/14
B25D 17/24
E21B 1/02
E21B 6/00
Applicants: FURUKAWA CO., LTD.

KANEKO, Tsutomu

Inventors: KANEKO, Tsutomu

Title: SHOCK-ABSORBING MECHANISM FOR HYDRAULIC HAMMERING DEVICE
Abstract:
The present invention relates to a shock-absorbing mechanism for hydraulic hammering devices such as machine drills, which mechanim damps an energy reflected from a shank rod (2) to reduce possible damages and permits a bit, even when a machine drill body (1) cannot advance to a predetermined position until a subsequent hammering after it has moved back due to insufficient thrust, to advance into contact with a base rock to enable striking thereagainst for improvement of hammering efficiency. A machine drill comprises a hammering mechanism for striking against the shank rod (2), and a chuck driver bush (13) for transmitting to the shank rod (2) a thrust toward an object being crushed. Provided rearwardly of the chuck driver bush (13) are a front damping piston (4), which provides less thrust than that of the machine drill body (1), and a rear damping piston (5), which provides greater thrust than that of the machine drill body (1).