Hr1 class (original classification P1) was the largest passenger express steam locomotive built in Finland. Twenty-two were built between the years 1937–1957. They were numbered 1000–1021In the thirties there was a need for faster and heavier express trains in Finland, and the Hv1–Hv3 classes were not powerful enough to fill the need. Lokomo Oy in Tampere built first two prototypes, and after successful trials 20 more were built.