In KALKI Avatar, Lord Vishnu will manifest himself as KALKI, the machine-man, who will come riding his white pony and with his blasting blade in his grasp. 

This should be a future symbol of Lord Vishnu. Toward the finish of Kali Yuga (present age) He will rebuff all scalawags in this world, obliterate this world and reproduce a brilliant age once more. 

KALKI is the remainder of the symbols of Lord Vishnu.