I guess, heavy equipment brakes can be huge. But I don't see the utility in them if they are static. Surely you'd use pliers to contract then release the springs? As I said, I don't have a clue, just postulating notions.
They are most likely some very unique type of restraint for a specific application no longer in use. Given they're cast iron, consider the time period of when they were made, and they vehicle/equipment of that era, and you get closer. Cast iron tools left us by the early 70s, so I'd venture a guess they belong to the 50s/60s or earlier.