| 摘要 |
PURPOSE:To smoothen rotation of a worm, by forming a worm tooth by a plurality of steel balls rollably arranged. CONSTITUTION:An hourglass worm 6 has an outer peripheral surface mating with an outer circumference of a worm wheel 4. The outer peripheral surface of the worm 6 is formed with a spiral groove 7 having an annular shape in cross section. The spiral groove 7 has a start point and an end point both communicated with each other through sectional circular guide holes 8, 8' and 8'' formed in the worm 6. A plurality of steel balls 9 are rollably arranged in the spiral groove 7 and the guide holes 8, 8' and 8'' in such a manner as to endlessly closely contact one another. Thus, a tooth of the worm 6 is formed by the steel balls 9. The worm wheel 4 has an annularly recessed outer circumference mating with the outer periphery of the worm 6. The outer circumference of the worm wheel 4 is formed with a plurality of teeth 10. Further, the worm 6 is surrounded by covers 12 and 12', so as to prevent escape of the steel balls 9. |
