Importance

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Abstract

An impact tool for mining, demolition work and the like. An energy storing device such as a coil spring, when compressed, accelerates a hammer to deliver a blow to a working tool. The hydraulic cocking mechanism has a compression chamber and a bias chamber. A shaft extends through the compression chamber and into the bias chamber. The shaft has an annular stop attached to it and reciprocally carries a compression sleeve above the annular stop. A bias member extends into the bias chamber. Input hydraulic pressure urges the bias member to press the compression sleeve into seating contact with the annular stop to define a piston. Hydraulic input pressure acting at the same time below the piston urges the shaft upward to cock the spring. At the top of the stroke, ports and passages reduce the pressure difference above and below the piston to allow the spring to force the shaft down for impact. On the downstroke, the compression sleeve and annular stop separate. Ports urge the sleeve back into sealing contact with the annular stop after impact. A resilient member cooperating with the sleeve and annular stop reduce damage to the sealing surface.

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First Claim