Clinchfield 4-6-6-4 pusher By Angela Cotey | December 29, 2021 | Last updated on January 6, 2022 Email Newsletter Get the newest photos, videos, stories, and more from Trains.com brands. Sign-up for email today! Get Updates Clinchfield Railroad 4-6-6-4 No. 672 lends a hand at the rear of a southbound coal train at Gray, Tenn., on May 28, 1952, not long before the road became 100 percent diesel. The road engine was another Challenger, No. 662. Ed Theisinger photo