Diesel locomotive T 669.0107 of the Czechoslovak State Railways. The nickname of the T 669 diesel locomotive series, later referred to as series 770, is derived from the Russian series designation ЧМЭ3 ("ChME3"), which sounds very similar to the Czech word for bumblebee "Čmelák." Additionally, it is named for its humming sound when starting up, which also resembles that of a bumblebee—at least from a distance. With its 1,400 horsepower, it proved itself in both light and heavy shunting service.