Hollow swivel actuator

A hollow swivel actuator comprising:

• a lower housing having a hollow cylindrical portion protruding upward at a center thereof;
• an upper housing stacked and assembled on an upper portion of the lower housing and having a through hole formed in a central portion thereof in which the hollow cylindrical portion protrudes upward through the through hole;
• a driving motor arranged on a bottom surface of the lower housing and having a cylindrical rotor worm gear integrally formed on an outer circumference of a cylindrical rotor support extending upward from the rotor;
• first to third gear trains arranged and coupled at intervals of 120 degrees on the outer circumference of the rotor worm gear protruding through the upper housing, and having first to third worm wheels formed to be gear-coupled to the rotor worm gear on one side of each of first to third power transmission shafts to achieve primary reduction and first to third worm gears formed on the other side of each of the first to third power transmission shafts;
• first to third pinion gear units having fourth to sixth worm wheels formed on bottom ends thereof so as to be gear-coupled to the first to third worm gears to achieve secondary reduction, and first to third pinion gears integrally formed on top ends thereof;
• and
• a rotational table in which the first to third pinion gears of the first to third pinion gear units are gear-coupled to a ring gear integrally formed inside a side portion thereof to achieve a tertiary reduction.