초록

A hydraulically driven hammer has a piston which contains metal piston rings on a constant diameter section. The housing has a plurality of axially spaced apart radial ports that extend through the housing into the bore. A valve supplies fluid to the ports to control reciprocation of the piston.

대표청구항 ▼

[ I claim:] [6.] An impact apparatus, comprising in combination:a tubular housing with an axial bore;a piston reciprocally carried in the bore and having a lower pressure area shoulder and an upper pressure area shoulder which is larger in cross-sectional area than the lower pressure area shoulder,

[ I claim:] [6.] An impact apparatus, comprising in combination:a tubular housing with an axial bore;a piston reciprocally carried in the bore and having a lower pressure area shoulder and an upper pressure area shoulder which is larger in cross-sectional area than the lower pressure area shoulder, the piston being movable between a lower rest position, an intermediate start position, an upper position, and an impact position;a working tool located at a lower end of the bore for contact by the piston;a fluid compression chamber at the upper end of the bore to supply energy to drive the piston from the upper position to the impact position;a plurality of axially spaced apart ports extending through the housing into the bore; anda plurality of axially spaced apart split, metal piston rings mounted on a constant diameter section of the piston for sealing to the bore of the housing, selected ones of the piston rings moving past selected ones of the ports during the movement of the piston between the start, upper and impact positions to control movement of the piston in cooperation with the valve means.