Emergency steering system for vehicle

An emergency steering system for a vehicle, comprising:

• a planetary gear apparatus mounted in an inlet space of a gear box for a steering apparatus wherein the planetary gear apparatus is operated at a gear ratio of 1:1 in a condition of normal operation and has an increased gear ratio in an event of failure of a main steering device;
• and
• a gear ratio increasing device mounted to an upper plate portion of the gear box to increase the gear ratio of the planetary gear apparatus,
• wherein the planetary goy apparatus includes:
• a small sun gear connected to a steering wheel;
• a plurality of first pinions engaged with the small sun gear;
• a large sun gear coaxially disposed behind the small sun gear;
• a plurality of second pinions engaged with the respective first pinions and the large sun gear;
• a ring gear inscribed and engaged with the second pinions;
• and
• a carrier connected to rotation centers of the first and second pinions while being restrainedly connected to the large sun gear, the carrier being mounted to the upper plate portion of the gear box, and
• wherein the large sun gear is separated from the carrier by operation of the gear ratio increasing device in the event of failure of the main steering device.