Patent ID: 7428845

Claim:
A method of tightening a workpiece bolt to a desired degree of compression utilizing a compression gauge comprising an hydraulic cylinder and a piston slidably disposed in said cylinder, said cylinder and said piston defining an hydraulic chamber, said cylinder and said piston containing an aperture; a threaded female receiving member positioned on one side of said compression gauge and aligned with said aperture; a test bolt having a head end and a threaded body, wherein said head end of said test bolt is positioned on a side of said compression gauge opposite said female receiving member, wherein said test bolt body is positioned in said aperture, and wherein said test bolt body is configured to rotationally engage said threaded female receiving member, whereby tightening said test bolt will force said piston toward said cylinder, compressing said hydraulic chamber; and a pressure gauge in fluid communication with said hydraulic chamber; wherein the method comprises: tightening said test bolt with an hydraulic wrench, said hydraulic wrench comprising an hydraulic cylinder operating on a line pressure and a torque control valve configured to control the line pressure available to said hydraulic cylinder; continuing to tighten said test bolt with said hydraulic wrench until a desired pressure, corresponding to a desired degree of compression, is obtained on said pressure gauge; setting said torque control valve to open at the line pressure at which said hydraulic wrench was operating when said desired pressure was achieved in said pressure gauge; and tightening said workpiece bolt with said hydraulic wrench until said torque control valve opens.