Drilling rigs require lots of power to be able to lift drill pipe, pump mud, turn the drill pipe to make hole and assorted other functions while seeking oil and gas deposits sometimes miles below the surface.
During the drilling boom of the early 80’s, I was working as the Oilfield Sales Manager for an industrial chain manufacturer. The specific chain that my company manufactured for oilfield drilling rigs was a roller chain.
A roller chain is just like the chain on your bicycle. The difference is that your bike chain is one strand, four feet long, and weighs a couple of pounds at most.