Illinois Pocket Watch with Dueber case movement s/n 4608783

Here is what I know about it... It was my Great Great Grandfathers watch. He was a Conductor for RailRoad Passenger Service back in the '1900 - '30's. I know that it has a movement s/n 4608783, the case says Dueber 25 year gaurantee it's s/n is 11225098. the movement as printed Illinois Sringfield Watch Co., 17 Jewel, Adjusted, Double Roller.
What can you guys tell me about it? Year Made, Number of units made similar to this one?, Approximate Value on Retail Market, ect...