56113 at Usan on the ECML in February 2020. ©Richard Birse
The British Rail Class 56 is a type of diesel locomotive designed for heavy freight work. It is a Type 5 locomotive, with a Ruston-Paxman power unit developing 3,250 bhp and has a Co-Co wheel arrangement. Enthusiasts nicknamed them "Gridirons" (or "Grids" for short), due to the grid-like horn cover on the locomotive's cab ends fitted to nos. 56056 onwards. The first 30 locomotives were built by Electroputere in Romania, but these typically suffered from poor construction standards and many were withdrawn from service early for extensive rebuilding before re-entering revenue service. The remaining 105 locomotives were built by British Rail Engineering Limited (BREL). The Class 56 proved to be a strong and capable locomotive type but its maintenance requirements and costs were relatively high compared to its contemporaries and modern locomotive classes. Despite this, several can still be seen in mainline use, with a trio of locomotives also preserved.
(Information provided via Wikipedia)