Tool driving or impacting – Impacting devices – Hammer head constitutes piston of drive motor
Reexamination Certificate
2007-01-02
2007-01-02
Smith, Scott A. (Department: 3721)
Tool driving or impacting
Impacting devices
Hammer head constitutes piston of drive motor
C173S135000, C173S138000, C173S200000, C173S128000
Reexamination Certificate
active
11014466
ABSTRACT:
An impact tool has a slidable hammer that is driven by hydraulic oil under pressure inside a chamber. The hydraulic oil is pressurized by a piston driven by compressed gas on the opposite side of the piston from the hydraulic oil. The gas in the gas chamber is compressed by the piston on an initial stroke, and has a large annular chamber holding the gas so that higher average gas pressure can be attained during the power stroke. As the piston is moved to compress the gas, the piston lifts a valve that opens a passage for the hydraulic oil moved by the piston to act on a hammer to impact a breaking tool. The piston is a two part piston that serves to lower the inertia during the final closing of the valve, and thereby reduces impact loads on the valve as it is closed. The valve also is controlled as to its stroke for efficient operation.
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Copy of International Search Report.
Copy of Written Opinion.
Berard Craig A.
Ottestad Jack B.
Clark Equipment Company
Nash Brian
Smith Scott A.
Westman Champlin & Kelly P.A.
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