This is just for everyone's knowledge about an exceptional case, there used to be a Self-generating LHB rake, having LHB shell + FIAT bogie with alternators connected to the wheels supplying power to the coaches (NOT to be confused with H-LHB). Observe the Y structure in bogie /blog/post/1465001
. This rake was with NR used for Shalimar Express initially, later on with ANVT-UHP SPL.
Learn more about the rake at click here
Underslung DG sets are present in SLR coaches but they are limited as due to vibration, the rdso has certified this type of SLR coaches to run at 110kmph only (maybe changed now).
Currently, trains on hog are mostly running with one Lwlrrm and one slr with no dg set and DL series coaches are slr with no dg set.
Yes, this rake was part of initial research by rdso to have lhb sleeper coaches for higher speeds.
Unfortunately, the concept was discarded after 1 year of its introduction.
Currently, the rake is used in anvt-uhp special via gzb, mtc, sre, umb