| Class 3900 | |
| Powertype: | Steam |
| Driverdiameter: | 900mm |
| Wheelbase: | 3.6m (11.8feet) |
| Hatnote: | Reference:[1] |
| Retiredate: | 1922 |
| Disposition: | All scrapped |
| Length: | 9.1m (29.9feet) |
| Locoweight: | 35.5 t |
| Fueltype: | Coal with heavy oil |
| Fuelcap: | 1 t |
| Watercap: | 3.50NaN0 |
| Builder: | Maschinenfabrik Esslingen |
| Builddate: | 1892 |
| Totalproduction: | 7 |
| Boilerpressure: | 176.5lb/in2 |
| Firearea: | 1.730NaN0 |
| Totalsurface: | 750NaN0 |
| Cylindercount: | Two |
| Cylindersize: | 39x |
| Valvegear: | Walschaerts |
The JGR Class 3900 was a type of steam locomotive used on Japanese Government Railways. The locomotives were imported from Germany for the Abt rack system railway built in Karuizawa, Nagano.[1]