The are a type of "Pacific" type steam locomotives built by Kisha Seizo Mitsubishi and Japanese National Railways (JNR) Hamamatsu Works. The C classification indicates three sets of driving wheels. The C51 introduced diameter driving wheels to Japan. C51s raised the average speed on the Tà Âkaidà  Main Line from to . In 1930, a C51 hauled the first Tsubame (swallow) express, reducing travel time between and to 9 hours.
To alleviate a severe motive power shortage, sixteen JGR Class C51 locomotives, C51 8, 28, 30, 33 - 35, 88, 95, 96, 116, 130 - 132, 173, 175, and 178, all equipped with a Sumiyama feedwater heater, were converted to standard gauge and sent to the Central China Railway in 1939, where they operated primarily between Nanjing and Shanghai, at first with their original JGR numbers, later as ãÂÂã·ã (Pashina) class. After the Liberation of China and the establishment of the People's Republic, these became China Railway class ãÂÂãÂÂ9 (PX9) in 1951, and reclassified as class SL9 (Ã¥ÂÂå©9, Shènglì, "victory") in 1959.
As of 2012, four Class C51 locomotives were preserved at various locations.