Clinchfield 4-6-6-4 pusher By | December 29, 2021 Email Newsletter Get the newest photos, videos, stories and more. 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