in 1999, a new twin converter transmission, the l 620 reu2, was developed for high-performance, main-line locomotives. the new l 620 reu2 was equipped with both a start-up converter, having a diameter of 525 mm, as well as a travel-phase converter, having a diameter of 434 mm. the design of the new l 620 re u2 was based on its successful predecessor, the l 520 rzu2 which had a power rating of 1,400 kw. this new transmission however was rated significantly higher at 2,700 kw and therefore virtually all of its components had to be enlarged as well as reinforced. in the standard version of the transmission, two gears were mounted on the secondary shaft rather than using the idler wheel found in the older l 520 rzu2. as a result, the drive shaft's output speed could be adjusted to suit the locomotive's power requirements. the drive shaft's main bearing was also enlarged to 550 mm. in general, this new high-performance transmission clearly illustrated the enormous capability of hydrodynamic couplings. with a weight-to-power ratio of only 2.06 kg/kw, the new l 620 reu2 set a record for locomotive transmissions. by comparison, the similar l 520 rzu2 transmission had a far higher weight-to-power ratio of 2.4 kg/kw. in addition, a newly designed hydrodynamic retarder, the kb 385, was available as an optional component. at vossloh, the locomotive manufacturer based in kiel, these transmissions were installed in both its g1700 and g2000 main-line locomotives. finally, the latest development is the ls 640 reu2 transmission which will be used for the first time in the voith maxima locomotive having 3,600 kw. the ls 640 reu2 is a so-called split turbo-transmission which uses two drive shafts from the l 620 reu2 to power both bogies of a six axle diesel locomotive.