US 5,350,023 AGranted

Pneumatic hammer

AssigneeIng. G. Klemm Bohrtechnik GmbH

InventorGuenter W. Klemm

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Abstract

A pneumatic hammer is provided with an adjusting piston (37) dependent on the supply pressure, which adjusts the stroke length of the working piston (16). Thereby, the same pneumatic hammer may be operated both at low and high supply pressures. With high supply pressures, either the early ending of the acceleration phase or the early start of the compression phase or the shortening of the working cylinder shortens the stroke length. Thereby, the pneumatic hammer performs impacts with a substantially constant single-impact energy, regardless of the supply pressure. High supply pressures increase the impact frequency. This results in a considerably improved efficiency at a high drill capacity, a reduced wear and a reduced risk of ruptures of the components of the hammer.

Claims13

Dependent claims

A pneumatic hammer having a working piston (16) movable in a working cylinder, said piston imparting impacts onto a drill bit via an anvil (15), and control members provided at said working cylinder and said working piston, which control a supply of compressed air to front and rear cylinder chambers (23, 24) at both ends of said working piston and which cooperate such that, during a return stroke, said working piston performs an acceleration phase and an air compression phase and that, during a subsequent forward directed working stroke, said working piston performs a drive phase and an impact on said anvil (15),

characterized in that
at a front end of said working cylinder there is provided a reciprocable adjusting means (37) for adjusting the length of the return stroke of said working piston in dependence on the supply pressure of the compressed air.

Dependencies are inferred from the claim text.