SBB Re 620
The Re 620, Re 6/6 in the old numbering scheme, are six-axle, electric locomotives of Swiss Federal Railways, which were acquired as a replacement for the Ae 6/6 for heavy services on the Gotthard Railway. They were produced between 1972 and 1980 and are the most modern of the so-called "Gotthard locomotives".
Construction and Technology
To reach the necessary tractive effort, a construction comprising six driven axles was necessary. In order to still get good running characteristics in curves, they were built into three two-axle bogies instead of two three-axle bogies as on the Ae 6/6. The middle bogie can move sideways, and the three bogies are connected by elastic cross couplings. Two of the four prototypes were built with a split locomotive body, whereby the joint may only move on an horizontal transverse axis to allow for changes in gradient, similar to the Rhaetian Railway Ge 6/6 II.The other two prototypes got a softer secondary suspension instead of the joint, which proved to be so reliable in everyday use that all other locomotives of the series were built this way. Nevertheless, the two prototypes with a split body are still in regular operation. The exterior design is similar to the Re 4/4II, as are the driver's controls and the conventional transformer technology with fixed running notches, which was applied for the last time for this locomotive. In contrast to the Re 4/4II, the Re 6/6 has two transformers, which are mounted on the frame between the bogies. Due to the higher roof, the Re 6/6 looks more brawny than the Re 4/4II, especially when seen from the front side.
Operations
The Re 6/6 is equipped with multiple unit train control together with Re 4/4II, Re 4/4III, Re 4/4IV and RBe 540. In passenger traffic they pull heavy passenger trains over the Gotthard route. In freight traffic they are used all over Switzerland for heavy trains, on the Gotthard route very often together with an Re 4/4II or Re 4/4III. Such a couple, often referred to as "Re 10/10", is capable of pulling the maximum train weight of on 2.6% gradients of the Gotthard line. For heavier trains, up to 1600 tons are operationally feasible, an additional bank engine has to help push the train in order to not overload the couplers.Locomotive 11638 was retired and scrapped in 1990 due to an accident. For the renumbering to the UIC-conforming new numbering scheme in 1992, only the still existing locomotives were considered, thus the 11638 did not get a new number. But the renumbering was never done consistently. During 2005, the UIC numbering scheme was reworked, and 620 001 was defined to be the smallest number. To make things easy, the scrapped 11638 also got a new number, 620 038. About half a dozen locomotives bore the new numbers at the beginning of 2006.
After two locomotives were tentatively equipped with radio remote control for pushing trains on the Gotthard line, about 30 locomotives were equipped with it in 2000. To make them administratively distinguishable, they got the new designation Ref 6/6.
When SBB was divided into passenger services and freight, the first thirteen locomotives remained in the passenger division. On 1 January 2003 they were exchanged against the Re 460, meaning that now all remaining 88 locomotives were assigned to SBB Cargo. Due to the reassignment of the Re 460 to the passenger division, the Re 6/6 again dominated freight traffic on the Gotthard line.
The locomotives are assigned to the workshops in Erstfeld, Bellinzona and Lausanne. Revisions are done at the main workshop at Bellinzona.
Naming and numbering
Since the Kantonsloks Ae 6/6, naming of locomotives and EMUs is common practice in Switzerland. Re 620 locomotives are numbered 11601–11689 and named after Swiss communes. In addition to the communes' names, also their coat of arms is indicated on the side of each engine.The following table lists Re 620 locomotives with their number, commune names and respective coat of arms. Crossed out numbers indicate scrapped locomotives.