Originally numbered 5, this Shay began service at Birch Valley Lumber Company, Tioga, West Virginia in 1922. Mower Lumber Company at Cass, West Virginia acquired the engine in 1943 and re-numbered it No. 4.
Shay Number 4, along with Number 7, expand present day No. 5's lineage by representing typical Lima Class C-70 locomotives built for West Virginia loggers during the 1920's. With it's well-proportioned diamond stack and arch-windowed cab, Shay No. 4 is a very traditional locomotive indeed. In 1965 Number 4's axels were replaced by the Cass Shop, using axles from a General Motors "GP-30". On October 3, 1985 Shay 4 broke one of those axles at mile five returning from helping the Bald Knob train. The 3 o'clock Whittaker train came up to mile five and the passengers were transfered around the disabled engine. The crews then took a spare wheel and axle set up to the site, using the log loader as a wrecking crane. They installed the wheel set on site. By 1:00 am all the trains were back at the shop. Although the engine could have been set aside until winter repair season, the crews went to work. They removed an identical wheel from Shay No. 7, because the set used to get off the mountain were not identical to 4's. Next they installed the "new" set on Number 4. The next night No. 4 was being tested and by the next day she was back on the Bald Knob run.
| Builder No.: 3189 | Date in Service: December 9, 1922 |
| Class: C-70 | Trucks: 3 |
| Bore: 12 inches | Stroke: 15 inches |
| Drivers: 36 inches | Weight: 80 Tons |
