Playmobil hybrid locomotiveWhy should you use a diesel locomotive if there is overhead wire on a railway line? Most diesel locomotives have a diesel engine that drives a generator that produces current for the electro motors in the locomotive. Therefore, a diesel motor is not really necessary. But in a yard, where you want to load a wagon from above, overhead wire is much too dangerous. At the other hand, a diesel motor is not environment friendly. The Swiss railways developed a shunting locomotive that runes under the wires, but if necessary can turn on a diesel locomotive when it is needed:
SBB class Eem 923.
SBB Caro Eem 923 hybrid locomotive.The idea is not completely new. Henschel developed the concept earlier, but uses batteries instead of a diesel motor: Henschel class
EA800. 
The Henschel EA800 has batteries instead of a diesel engine.I wanted such a locomotive on my layout, and thus Rebuilded Playmobil diesel locomotive 5258. I removed the ventilation cover on the roof and replaced it by a pantograph. Such item can still be found second hand or at eBay. The result: I have my own environment friendly hybrid locomotive!
My Playmobil hybrid locomotive.
