When the Palms in Ardhachandra mudra touch each other vertically and horizontally we get the Chakra Mudra. The right palm is vertically held and the left palm is horizontally placed over the it.
Lets tale a look at the viniyoga shloka (uses)
It says that this Mudra denotes a Wheel. In Sanskrit Chakra means a circle or a wheel.
Very often in Dance this hasta is used to represent Lord Vishnu’s Sudarshan chakra. He is dipicted holding it with his right forefinger. This chakra is a Divine weapon with sharp edges and is supposed to spin like a Disc.