PKP Class Pt31 is a Polish steam locomotive of Polskie Koleje Państwowe, designed for hauling heavy long-distance passenger trains, built in 1932-1940. The designation stood for fast passenger (P) 2-8-2 (t) steam locomotive designed in 1931. Pt31 became the strongest machines hauling long-distance passenger trains in Poland. A maximum speed was 110 km/h (68 mph). It could achieve at least 105 km/h with a train of 600 tonnes (590 long tons; 660 short tons), or could haul the train of 810 tonnes (800 long tons; 890 short tons) with lower speed.