| 摘要 |
It is an object of the invention to provide an effective technique for reducing wear of sliding contact areas in an engagement clutch of a rotary tool. According to the invention, a representative rotary tool may comprise a motor, a tool bit, a driving-side clutch element, a driven-side clutch element, a biasing spring, a rotation preventing member and an enclosure. The biasing spring biases the driven-side clutch element toward the power transmission prevented position. The biasing spring is disposed in a compressed state on the outer peripheral side of the driving-side clutch element and the driven-side clutch element and extends between the driving-side clutch element and the driven-side clutch element. At least part of the biasing spring is enclosed by the enclosure. Lubricant deposited on the inner wall surface of the enclosure is supplied to either a sliding contact area between the biasing spring and the driving-side clutch element or a sliding contact area between the biasing spring and the driven-side clutch element by rotation of the biasing spring. According to the invention, lubricant applied to the engagement areas flies outward by rotation of the driving-side clutch element and deposited on the inner wall surface of the enclosure. Then, the deposited lubricant is actively supplied to the sliding contact areas between the biasing spring and the driving-side clutch element or the driven-side clutch element by utilizing rotation of the biasing spring. Thus, the effect of lubrication of the sliding contact areas can be enhanced.
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