Two Norwegian steam locomotives at the railroad museum in Hamar. On the left, the 4-6-0 class 27a # 234, built at Thunes mekaniske verksted, Christiania in 1912 (construction # 55). NSB Type 27a locomotives were called "Sydbaneracers" because the first locomotives of this type were used on the southern lines in the districts of Drammen, Hamar and Kristiansand. They were light and fast locomotives for operation on lines with low axle loads, with 1600 mm driving wheel diameter and 75 km/h maximum velocity. When the expansion of the lines for which they were originally supplied took place, they were transferred to lower-value services. After World War II, the 27a ran on the Indre Østfoldbane until electrification on December 17, 1958. On the Rørosbane, the class was responsible for the 301/302 Hamar-Tynset passenger train pair until 1961, when it was replaced by the Type 26; the 373/374 Hamar-Rena passenger train pair until August 4, 1963 (replaced by railcars); and the 377/378 Hamar-Koppang passenger train pair until May 31, 1959 (replaced by railcars). Shorter trains on the Vestfoldbane were part of its duties until its electrification in December 1957. The last area of operation until 1969 was the Elverum-Kongsvinger line, on which ballast trains were to be hauled. The last 27a # 234 to be taken out of service on September 29, 1969, has been preserved and stands in the locomotive hall of the Norsk Jernbanemuseum in Hamar.
On the right, the 4-8-0 series 31b # 452, built by Hamer & Thune in 1926 (construction # 334). The series was a further development of the NSB Type 26 series. It was one of NSB's largest steam locomotive series and hauled the most important trains on the non-electrified lines, primarily on the Bergenbane and Gjøvikbane, as well as in the Hamar and Trondheim rail districts. The second series 31b with 23 locomotives was a four-cylinder compound locomotive. This means that the steam expanded first in two high-pressure cylinders and then in two low-pressure cylinders. This resulted in better utilization of steam and lower coal consumption. The 31b was therefore better suited to pulling heavy trains on long grades than the 31a. The Bergenbane with its gradients was therefore the main area of use for the 31b locomotives until the end of the 1950s. # 452 has been preserved and is in the Norsk Jernbanemuseum in Hamar. It was last in service as a reserve locomotive at Otta until October 8, 1968.
