The 'X' is named after the instrument of torture, the breaking wheel, on which, legend has it that St. Catherine was martyred.
In Malta, 'X' are very popular, and in Maltese, they call them "Irdieden". The most known place for 'X' is Haz-Zebbug, where they fill a whole road with them from small to ones with large complex gear work. Different types of 'X' – include "timed," "gearwork," and "simple" –that last for different durations.
How is 'X' better known in india...:)
'X'-Catherine wheel better known as the chakri in india
Catherine wheel or 'Chakri' in India