Southern Railway 1643

4 ft 8+1⁄2 in (1,435 mm)Driver dia.50 in (1.270 m)Fuel typeCoalFirebox:​ • Grate area29 sq ft (2.7 m²)Boiler pressure185 psi (1.28 MPa)CylindersTwo, outsideCylinder size20 in × 26 in (508 mm × 660 mm)Valve gearStephenson

Performance figures
Tractive effort	32,710 lbf (145.5 kN)

Career
Operators	Southern Railway Morehead and North Fork Railroad
Class	A-7
Numbers	1643 (SOU) 12 (M&NF)
Retired	1963
Restored	July 16, 2018
Current owner	Age of Steam Roundhouse
Disposition	Operational, based in Sugarcreek, Ohio

Southern Railway 1643 is a preserved A-7 class 0-6-0 "Switcher" type steam locomotive built in 1905 by the Pittsburgh Works of the American Locomotive Company for the Southern Railway.

In 1952, the locomotive was sold to the Morehead and North Fork Railroad in Morehead, Kentucky. Renumbered 12, the locomotive operated on the Morehead line, until the company dieselized on April 1, 1963.^[1] After the locomotive was retired, it was put into storage in one of the road's engine sheds. In 2011, No. 12 was purchased by Jerry Jacobson, who moved it to his Age of Steam Roundhouse building in Sugarcreek, Ohio. The locomotive was restored to operating condition in 2018, and it moved under steam for the first time in the 21st century on July 16.^[2]