Electrically operated screw-type jack

A screw-type jack comprising:

• a support base;
• a jack body mounted on said support base;
• a housing mounted on said jack body, said housing having a flange formed at a middle portion thereof;
• a servo motor having a driving gear mounted to a lower end thereof, said servo motor being contained in said housing;
• a lifting ram vertically mounted on said support base, said lifting ram being contained in said jack body;
• a driven gear and a driven pinion mounted on said support base, said driven gear and said driven pinion in engagement with each other;
• reduction gears having first sun and planet gears including first planet gears and a center gear, second sun and planet gears including second planetary gears and a driving pinion, a sun gear cylinder housing said first and second sun and planet gears therein, said sun gear cylinder having fitting projections formed at lower end thereof;
• a safety device mounted under said reduction gears, and having a clutch disk on which are formed fitting recesses, said fitting recesses disengagably receiving said fitting projections of said sun gear cylinder;
• a clutch spring resiliently supporting said clutch disk in engagement with said lower end of said sun gear cylinder;
• and
• a sleeve mounted detachably to said flange of the housing by bolts, said sleeve having a cylindrical support formed at the bottom thereof, said sleeve and said cylindrical support housing said reduction gears and said safety device therein.