Control of variable-stroke power hammers

Claim 1

IN COMBINATION WITH A HIGH SPEED RECIPROCATING HYDRAULIC POWER HAMMER HAVING A CYLINDER AND OPERATING PISTON: A SOURCE FOR SUPPLYING LIQUID UNDER PRESSURE; VALVE MEANS FOR CONTROLLING THE ADMISSION OF LIQUID FORM SUCH SOURCE INTO THE CYLINDER SPACE FOR SUBJECTING THE PISTON TO A PRESSURE WITHIN A NORMAL PREDETERMINED RANGE FOR ACTUATING THE PISTON ON ITS WORKING STROKE, SAID VALVE MEANS BEING ACTUATABLE FOR THEREAFTER CONTROLLING RELEASE OF THE LIQUID FROM SAID SPACE UPON THE RETURN STROKE OF THE PISTON, SUCH PRESSURE IN SAID SPACE BEING SUBJECT TO AN ABRUPT INCREASE CAUSING A WATER HAMMER IMPULSE UPON STOPPING OF THE PISTON MOVEMENT AS THE RESULT OF THE STRIKING OF A HEAVY BLOW BY THE HAMMER; AND MEANS ACTING RESPONSIVE TO THE KINETIC ENERGY OF SUCH IMPULSE FOR CAUSING SUCH VALVE ACTUATION AND CONSEQUENT RELEASE OF THE LIQUID FROM SAID SPACE.