Hammer drill

Claim 1

A FLUID-OPERATED WELL-DRILLING MECHANISM COMPRISING A TUBULAR HOUSING, AN INVERTED CUP-LIKE CYLINDER LONGITUDINALLY MOUNTED IN THE TOP OF SAID HOUSING, MEANS AFFORDING OPERATING FLUID ACCESS TO THE INTERIOR OF SAID HOUSING BELOW SAID CYLINDER, AN ELONGATE ANNULAR HAMMER SMALLER IN DIAMETER THAN THE INSIDE DIAMETER OF SAID HOUSING AND SLIDABLY DISPOSED IN AND SEALED AGAINST THE INSIDE OF SAID CYLINDER, SAID HAMMER HAVING A LONGITUDINAL CENTRAL PASSAGE THERETHROUGH, AN ANNULAR VALVE SLIDABLY DISPOSED ON AND SEALED AGAINST THE OUTSIDE SURFACE OF SAID HAMMER, THE INSIDE DIAMETER OF SAID VALVE BEING LESS THAN THE INSIDE DIAMETER OF SAID CYLINDER, A PASSAGEWAY LEADING FROM SAID LONGITUDINAL CENTRAL PASSAGE OF SAID HAMMER TO A POINT OUTSIDE SAID HAMMER PROXIMATELY BELOW SAID VALVE, A FIRST ANNULAR LEDGE ON THE INSIDE SURFACE OF SAID HOUSING BELOW SAID VALVE, THE LOWER END OF SAID VALVE BEING ADAPTED TO SEAT ON THE UPPER PORTION OF SAID FIRST LEDGE TO FORM AN ANNULAR SEAL, A STOP ON SAID HAMMER LIMITING UPWARD MOVEMENT OF SAID VALVE ON SAID HAMMER, A SECOND ANNULAR LEDGE IN SAID HOUSING BELOW SAID VALVE, A COLLAR ON SAID HAMMER BELOW SAID SECOND LEDGE ADAPTED TO PENETRATE SAID SECOND LEDGE AND FORM A SLIDING SEAL THEREWITH, AND A BIT STEM SLIDABLY DISPOSED IN AND SEALED AGAINST SAID HOUSING BELOW SAID HAMMER AND HAVING A LONGITUDINAL CENTRAL PASSAGE, THE UPPER END OF SAID BIT STEM BEING DISPOSED TO BE STRUCK BY THE LOWER END OF SAID HAMMER.