Abstract: A three-axis vibration acceleration pickup with the handle of a vibration-generating tool such as, an angle grinder or the like, feeds detected vibrations along the three axes to an A/D converter 19. A microcomputer processes the digitized data to feed a display portion. Each time continuous operation of the tool is interrupted, an 8-hour equivalent acceleration value is obtained based on the detected vibration acceleration signal. The result is added to previous acceleration values so as to accumulatively add up the total value in one day. Each time continuous operation is interrupted, a frequency load vibration acceleration value is obtained, and an 8-hour equivalent acceleration value is obtained based on this. A residual surplus time is obtained and displayed by using the 8-hour equivalent acceleration value.

Abstract: A pressure leading path in a impact type tool is branched halfway through a bypass passage for connecting a high pressure chamber H with a low pressure chamber (L). The branch includes a first fixed aperture leading to the high pressure chamber (H). The branch also includes a second fixed aperture leading to the low pressure chamber (H). The pressure leading path is connected to a primary side of a relief valve. An automatic shutoff mechanism is operated by hydraulic operating fluid relieved from the secondary side of relief valve. The automatic shutoff mechanism cuts off the air supply to the air motor driving the tool, and thus automatically shuts off the tool, when the pressure in the pressure leading path exceeds a predetermined value. The present invention permits control of pulsed torque with high precision in a simple construction.