| 摘要 |
A grinder 1 includes a spindle 9 having a small-diameter section 11 and a medium-diameter section 12 and a motor shaft 5 on which a pinion gear 6 is provided. The grinder 1 further includes a bevel gear 18 which is provided on the small-diameter section 11 of the spindle 9 and engages the pinion gear 6, and a lock sleeve 17 provided below the bevel gear 18 on the medium-diameter section 12. A coupling groove 21 is provided in the lower surface of the bevel gear 18 opposing the upper surface of the lock sleeve 17. The coupling groove 21 has an external diameter coaxial with and equal to the inner diameter of the lock sleeve 17 and further has an inner diameter coaxial with and equal to the external diameter of the medium-diameter section 12. An inner coil spring 22 is fitted around the second peripheral surface such that half the length of the coil spring covers the inner peripheral surface of the coupling groove 21, whereas the other half covers the outer peripheral surface of the medium-diameter section 12. In addition, an outer coil spring 23 is fitted around the first peripheral surface such that half the length of the coil spring covers the outer peripheral surface of the coupling groove 21, whereas the other half covers the inner peripheral surface of the lock sleeve 17. The grinder 1 additionally includes a gear housing 3 and a locking device 25 for locking the bevel gear 18.
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