The F-1 was a class of 2-6-0 locomotives with relatively large drivers for fast freight services. Production started in 1895 at Altoona and by 1901, 183 had been completed. Compared to the H-3 Consolidation introduced in 1885, the Mogul had a higher adhesive weight spread over only three driving axles, drivers which were twelve inches larger and also larger cylinders. So it had a greater tractive effort and its boiler could also generate more power due to its higher pressure. In the result, the F-1 was well suited for fast freight trains of medium weight, but was also able to handle 2,700 tons on the level. Four locomotives with the same boiler, but compound drive formed the class F-2 and were rebuilt to the F-1 in 1902 and 1903. Most were retired between 1915 and 1920, but some also survived until 1924.