Title:
液圧孔内ロックドリル機
Document Type and Number:
Japanese Patent JP4459225
Kind Code:
B2
Abstract:
A hydraulic drill string device can be in the form of a percussive hydraulic in-hole drilling machine that has a piston hammer ( 50 ) with an axial through hole ( 51 ) into which a tube ( 35 ) extends. The tube forms a channel for flushing fluid from a spool valve ( 62 ) and the tube wall contains channels ( 40 ) with ports ( 41,42 ) cooperating with the piston hammer for controlling the valve.
Inventors:
Fredrik Egerstrom
Application Number:
JP2006507959A
Publication Date:
April 28, 2010
Filing Date:
March 16, 2004
Export Citation:
Assignee:
Vasara Actie Borrag
International Classes:
E21B1/12; E21B4/14
Domestic Patent References:
| JP62038994U | ||||
| JP9506687A |
Attorney, Agent or Firm:
Chika Takagi
Junji Yuda
Shoji Miwa
Junji Yuda
Shoji Miwa