Complex sentence: Through collective bargaining, the UWA and the Pittston Coal Company established two different retirement plans for the miners: one for those who retired before 1974 and one for those who retired after 1974.
Split into simpler sentences: Through collective bargaining, the UWA and the Pittston Coal Company were able to set up two different retirement plans for the miners. One for those who retired before 1974 and one for those who retired after 1974.