| 摘要 |
PROBLEM TO BE SOLVED: To suppress breakage of a component part due to a collision between a piston and a hammer caused by wear or the like of a piston seal or a hammer seal in an impact tool driven by a motor. SOLUTION: A strain gauge 1 is glued near to a crankshaft journal portion of a crankcase 5, and a control board 4 for detecting and recording an output of the strain gauge 1 is arranged about it. The strain gauge 1 and the control board 4 are connected with wiring. The control board 4 carries an LED 7, which is arranged visibly from outside a body through a hole cut in the crankcase 5. The control board 4 checks whether the output of the strain gauge 1 exceeds a given value, and if it is exceeded, lights or blinks the LED 7 on the control board 4, or shuts off an impact tool driving power circuit. COPYRIGHT: (C)2003,JPO
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