From Germany to the SBB - The class 200 (later the class 220) heavy diesel locomotives purchased in the 1950s by the German Federal Railroad were taken out of service toward the end of the 1980s and some of them were sold. On the one hand the increasing electrification of the DB's route network had decreased the need for diesel locomotives, and on the other hand the maintenance costs were too high by today"s standards for this first large German diesel locomotive with its two separate propulsion systems. Many of these units were therefore sold to private German railroads and abroad. The SBB also acquired 7 of these large diesel locomotives from the DB and starting in 1987/88 designated them as the class Am 4/4 in its motive power pool. These locomotives were needed in Switzerland to transport material for extensive rebuilding of main lines. Since there is no working catenary present for such construction work, the SBB was looking for powerful diesel locomotives, which were unavailable in Switzerland in sufficient quantities. Since these locomotives were also used at night for this track work, the former DB flagship locomotives were completely overhauled and equipped with expensive sound insulation for the motors in order to minimize the noise for residents near the tracks. A few years later after their use in track construction the Am 4/4 locomotives went back to Germany to railroad material suppliers.