Class 19 is the name given to an experimental railway locomotive that was constructed using a Mark 3 DVT. The locomotive is part of a project funded by the Rail Safety and Standards Board to test the viability of combining hydrostatic transmission with a form of regenerative braking that can reduce engine emissions.

Hydrostatic transmissions have been used previously for rail vehicles, but only for slow-speed track maintenance vehicles and similar, not for mainline locomotives. Diesel-hydraulic locomotives instead use a hydrodynamic, i.e. torque converter, transmission.