 NSB ordered three El 9 locomotives from Thune on 4 October 1940 . The units were delivered in 1942 , with the electrical components from NEBB and the transformers and controllers from Per Kure . A delay was caused by bombing of Per Kure by the resistance . The locomotives were custom @-@ built for the steep gradients on the Flåm and Hardanger Lines , and were delivered with an axle load of 12 tonnes ( 12 long tons ; 13 short tons ) and a Bo 'Bo ' wheel configuration . The locomotives weighed 48 tonnes ( 47 long tons ; 53 short tons ) and the maximum permitted train weight was 85 tonnes ( 84 long tons ; 94 short tons ) . If the trains were to stop at Kårdal , the weight was further limited to 65 tonnes ( 64 long tons ; 72 short tons ) . 
