| 摘要 |
<p>The present invention comprises: a housing having a space portion formed therein; a main shaft which is provided in the space portion and has a worm wheel coupled along the outer circumference thereof; a pair of worm shafts which are disposed to be engaged with the worm wheel at both sides of the worm wheel in a predetermined location of the space portion; a driving motor provided on one side of the housing; a power transmission member provided on an upper surface of the housing so as to transmit the driving force of the driving motor to the pair of worm shafts; and a clearance adjusting member provided at a predetermined location of each lower end of both sides of the housing.</p> |
