Title:
A HAMMER DRILL
Document Type and Number:
WIPO Patent Application WO/2014/068500
Kind Code:
A3
Abstract:
The invention provides a control rod (6) for a drill hammer (1) comprising a flow passage (8) extending from an inlet at a back head end (2) to an outlet adjacent an opposite, inner end which is slidably locatable inside a bore (16) of a piston (4) and having a check valve (7) located at the outlet. The check valve (7) may be provided as a closure (26) having an enlarged head in sliding sealed engagement with the flow passage (8). The head has a stem (14) extending to an inner end of the control rod (6). A compression spring (9) is located around the stem (14). On the opposite side of the enlarged head is a working face (34) upon which pressurized air acts to compress the spring (9) and thus open the check valve (7). The free end of the stem (14) may either abut against a plug (52) in the rod inner end or pass through an opening in the end wall (32) and abut on the opposite side of the end wall with a stop (29) formed on the free end of the stem (14). The check valve (7) opens when the spring (9) is compressed. In this condition the enlarged head exposes radial ports (18) in the control rod side walls for the passage of air.
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Inventors:
GIEN BERNARD LIONEL (ZA)
Application Number:
PCT/IB2013/059791
Publication Date:
January 22, 2015
Filing Date:
October 30, 2013
Export Citation:
Assignee:
GIEN BERNARD L (ZA)
International Classes:
B25D9/14; E21B4/14
Domestic Patent References:
| WO2012056434A1 | 2012-05-03 |
Foreign References:
| US4530408A | 1985-07-23 | |||
| US20040016154A1 | 2004-01-29 | |||
| GB2010714A | 1979-07-04 |
Attorney, Agent or Firm:
DE BEER, Deon (PO Box 1238Rivonia, 2128 Johannesburg, ZA)
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