[1] They were nicknamed Kukko ("Rooster" or "Cockerel")[1] and they have the same frames and boiler as the Vr Class Pr1 (Paikku) locomotive.

It was a success, but in the hands of inexperienced drivers, it could all too easily damage buffers or break couplings.

They were deliberately designed to work within very large rail yards, where the overall noise level could be very high.

For half a century, the chirpy crow of the "Rooster" was a familiar sound in Finnish marshalling yards.

They proved to be agile and could easily scale the humps and complex pointwork of marshaling yards where their great power compensated for their low speed.