myaroslav
Most of pre-war soviet locomotives were named after communist leaders: IS for Iosif Stalin, VL for Vladimir Lenin etc. But it's hard even for soviet citizen to guess who is mr PB. This acronym is unique - it stands simultaneously for all leaders joined in the Political Bureau, the decision-making center of the soviet empire. The design and fate of PB21 loco built in 1934 are also rare for Soviet union. Intended to work with fast passenger trains, the engine received the same 4-6-4 type as fastest steam streamliners of the time. There was lack of experience in the suspension design, and mechanics inherited many steam-era details such as bar mainframe. Each driving axle was powered with two engines. The solution was quite popular for high-speed passenger locos of 1920-1930s, being applied at GG-1 and some European types. AEG quill drive have been chosen as prototype after many designs were compared. Having the electric equipment taken from mass produced 6-axle VL19 freight engine, PB21 proved to be a success. Easy to maintain locomotive was able to double the speed on the grades compared to typical steam locos. To enable operation in Moscow where initially 1.5 kV DC system was chosen locomotive was converted to dual-system in 1940, following the modernization of its freight prototypes. It remained in service from 1934 to 1955 and was retired in 1961 when new passenger locos become available and was preserved by depot. The success of the prototype obviously lead to idea of building a series of same locos. The revised project was soon prepared with streamlined GG1-like hood. Small improvements to receive smoother running were added. The transition to 2-Do-2 type was also discussed considering increased weight of passenger trains. However, as many projects and improvements of the time, it wasn't bearable economically. Heavy freight C-Cs were in priority, and PB21 remained in the long range of interesting but unsustainable soviet designs. Passenger locos, if needed, were received just by changing the gear ratio of some freight ones. I assume this project was in the mind of soviet engineers while placing the order for 2-Do-Do-2 Little Joes (if they weren't the same people). However, after the ban of GE loco delivery the history repeated. Once more the need in slow and simple freight locos was urgent. Post-war industry started with copying old C-Cs with minimal alterations as fastest and cheapest to build, but no more projects with leading trucks were ever considered. The time went and new high-speed suspensions not requiring leading trucks became widespread. #trainspotting #photo #train #electric
