This is more a prototype/demonstrator/tech art than useful. 

A working and useful model can be found here

While the reduction would allow high forces - at this scale the gear will slip, so this is more to move things very precise.

Scaled up it would probably work to hold higher forces

Between the small rod and ring grip is a ratio of ~2.6  while 1 rotation of the knurled rod move the tongs 1 tooth together or 9° (360:40)  wich results in a ratio of 22.4:1 for the grip and ~60:1 for the knurled rod .