This gear came from a possibly experimental mechanism that Glenn Streeter found in the Rock-ola building in Chicago when he bought the company about 1992. 

It was not a complete mechanism and it showed signs of having been used as a testing platform of some sort. 

This heavy steel gear was on the front end of the main shaft that goes through the record drum. 
I counted 96 teeth and it is about 4.125 inches in diameter. 
The center hole is about 0.625 inches.