| HH1s class | |
| Powertype: | Steam |
| Designer: | Francis Cole[1] |
| Builder: | ALCO |
| Builddate: | 1911 |
| Fueltype: | Coal |
| Fireboxtype: | wagon-top |
| Cylindercount: | Four |
| Valvegear: | Walschaerts |
| Valvetype: | Piston |
| Operator: | Pennsylvania Railroad |
| Operatorclass: | HH1s |
| Fleetnumbers: | 3396 |
| Retiredate: | 1928 |
| Disposition: | scrapped |
The Pennsylvania Railroad's class HH1s comprised a single 2-8-8-2 type steam locomotive.[2] Unlike most Pennsylvania Railroad steam locomotives, it had a wagon-top boiler. It was built by the American Locomotive Company (ALCO) in 1911. For 17 years, the single HH1s served as a helper until 1928. It had the road number 3396 and was subsequently scrapped after it was taken out of service in 1928.