I worked at an auto salvage yard back in the early to mid 70s' while I was in college. They had one of those but I never got to see it run. I am very sure it was an antique, can't even guess the year, but it was already old when I was working there. The yard had been there for a LONG time. The had an old photo of the yard and building with 100's of model "T" vintage cars in the yard. Of course those they were all gone with I was there.

The yard had two sections, the front where cars that still contained good parts. After the good stuff had been sold off, they were moved to the back section where they were separated. There were huge pile separated into; engines and cast iron transmissions, high aluminum content automatic transmission, rear axles, frames, and stripped bodies.

The shear was in a shed out back. I was amazed at the massive castings. It was powered by a BIG electric motor through a series of gears. I am thinking 2 maybe 3 pinion/spur gear reductions. With the final spur gear connected to the jaw by a REALLY thick connecting rod. I have to imagine that when it was in operation, it was continious, jaws just opening and closing continuously while someone fed material to it.