| PRR D1 | |
| Powertype: | Steam |
| Builder: | PRR Altoona Works |
| Builddate: | 1868–1872 |
| Totalproduction: | 13 |
| Whytetype: | 4-4-0 |
| Uicclass: | 2′B |
| Leadingdiameter: | 260NaN0 |
| Driverdiameter: | 680NaN0 |
| Wheelbase: | 22feet (locomotive) 44inchesftNaNinchesin (ftin) (overall) |
| Length: | 54inchesft6.44inchesin (ftin)[1] |
| Width: | 9feet |
| Height: | 14feet |
| Weightondrivers: | 423701NaN1 |
| Locoweight: | 777001NaN1 |
| Tenderweight: | 514001NaN1 |
| Locotenderweight: | 1291001NaN1 |
| Tendertype: | Eight-wheel with water scoop |
| Fueltype: | Soft coal |
| Fuelcap: | 80001NaN1 |
| Watercap: | 2400usgal |
The Pennsylvania Railroad's steam locomotive class D1 (formerly Class A, pre-1895) comprised thirteen 4-4-0 locomotives for express passenger service, constructed at the railroad's own Altoona Works (now owned by Norfolk Southern) during 1868–1872.[2] They were the first standardized class of locomotives on the railroad and shared many parts with other standard classes.[3]
The PRR was the first American railroad to adopt the Westinghouse air brake, the first tests of which were made in September 1869; Class A locomotives were among those fitted with air brake equipment for those earliest tests.[4] [5]
They remained in service until 1945, and were all withdrawn and scrapped by 1946.
