mariu5z

Adding a third cylinder would make it a bit more than just a detail difference. A good source on the subject is the book "Parowozy normalnotorowe produkcji polskiej" (Polish-built standard gauge steam locomotives) by Bogdan Pokropiński. He states that in 1930 HCP works in Poznań, Poland received an order to build 12 heavy tank engines for the mountain freight service. Bulgarian railways were already planning to buy those in Germany in 1919-1920. The engine was designed by the German engineer August Meister in 1921 and it was to be built by "Schwartzkopff" in Berlin. However due to some unspecified circumstances the transaction has not materialized at that time. Instead, after almost a decade, the order went to the polish HCP factory. I believe the blueprints were obtained from Germany and presented to Polish engineers who built the engines according to those. I hope that explains the German influence on the polish built locomotive. There are some excellent detailed graphs showing the speed to power ratios of both designs at the following link http://www.railwaymodeling.com/ however the site seems to be down at the moment. Once it comes back online, you may use Google Translate to navigate trough the Bulgarian language site. At least that's what I do.