SJ Class Rc6 Electric Locomotive
In the first half of the Sixties, the Swedish State Railways (SJ – Statens Järnvägar) worked intensively on replacing their old side rod electric locomotives. The Swedish locomotive builder ASEA built on this goal and came up with six four-axle test locomotives in 1962, the classes Rb1, Rb2, and Rb3 with the usual stepped relay control. Thyristor technology was certainly already in existence, but still not completely developed. Yet, a tentative conversion of road number Rb1 1001 in 1965 to control with thyristor rectifiers brought the desired success. It now allowed continuous acceleration of the locomotive to the desired speed with exact and variable control of the motor current without changing between various running modes. In addition, a continuous increase in pulling power could be achieved, which led to a 25% to 30% higher utilization of tractive effort. Additional advantages were less risk of slippage and lower maintenance.
In the end, the unit now known as road number Rb1T 1005 now served as the prototype for the new class Rc, which was then bought from ASEA in six production runs with minor changes between 1967 and 1988. Road numbers Rc1 1007-1026, Rc2 1027-1056 and 1067-1136, Rc3 1057-1066, as well as Rc4 1137-1200 were all equipped with four each 900 kilowatt type LJH108 motors. With the exception of road numbers Rc3 1057-1066 (maximum speed 160 km/h / 100 mph), they had a maximum speed of 135 km/h / 84 mph. Road numbers Rc5 1323-1382 (135 km/h / 84 mph) and Rc6 1383-1422 (160 km/h / 100 mph) followed, also with four each 900 kilowatt type LJM450 motors, Rc5 1323-1382 (135 km/h / 84 mph) and Rc6 1383-1422 (160 km/h / 100 mph) now with new ergonomic cabs with air conditioning, end windows made of bulletproof glass, improved thyristor rectifiers and traction motors, a vehicle computer for malfunction reporting, as well as larger air intakes. All of the Rc units had a locomotive body mounted on the frame as a welded, self-supporting design with side walls reinforced by ribbing. These side walls had four round bull's eye windows and a door as well as small ventilation grills on the edge of the roof. The frame and locomotive body rest on a weight-sensing load bar, which rests on four coil springs and on two each two-axle trucks employing box girder construction.
Over the years, there were various conversions and modifications. All total 23 Rc2 units mutated to Rc3 in the Nineties by changing the gear reduction to a maximum speed of 160 km/h / 100 mph. Between 1992 and 1995 all Rc5 units were converted to the class Rc6 in a similar fashion. With the division of the SJ into various business areas on January 1, 2001, the SJ AB (passenger train service) was given all Rc3 and Rc6 units. The former were all sold in 2014, and the latter are still used currently only in passenger train service as a rule. The freight service sector Green Cargo (GC) by contrast received the Rc1, Rc2, and Rc4 units. Most of the Rc1 units are in storage and are no longer on the Green Cargo roster, while most of the Rc2 units (since converted to Rd2) and Rc4 units are still to be found pulling GC freight trains.