Another aspect of diesel turbocharging, is turbo compounding, specifically mechanically compounded engines. These systems harness additional exhaust energy and apply that power via a mechanical coupling to the crankshaft of the engine. Detroit Diesel (Daimler) early DD15 engine that replaced the 60 series had turbo compounding until they had to ditch it because it interfered with the EGR system too much.

So sort of the other end of the spectrum of EMD's geared turbos. Whereas the mechanical drive there is to provide pressurization until there is sufficient exhaust energy, a mechanically compounded turbo takes excess exhaust energy that cannot be used for intake charging processes and applies that force to the crankshaft.