WILMERDING, Pennsylvania — By July of this year, the last man on the job here at the Westinghouse Air Brake Technologies Corporation will, in all likelihood, turn around as he reaches the threshold of the same front door hundreds of thousands of workers have passed through since the 1890s. For the last time, he will look out over the 300,000-square-foot plant that has provided this country with so much technology and innovation for nearly 140 years, and he will think about the men and women who went before, and then turn out the lights for the last time.