Zi U-5 - History of Development

History of Development

The first decade after Second World War was a period of huge expansion of trolleybus systems in the Soviet Union. They were considered as an innovative decision in comparison with "semi-obsolete" and expensive trams. The mainstay for trolley fleet for that time was extremely simple, reliable and durable MTB-82 vehicle. But it was medium-sized and uncomfortable for both driver and passengers. After small series and experimental TBU-1 vehicles ZiU developed completely new model for mass production with all disadvantages of MTB-82 eliminated. This was first variant of ZiU-5. More than 200 vehicles were produced for wide testing on Moscow streets in 1959. This huge testing work discovered the weaknesses of new design. Trolley depots in collaboration with ZiU and "Dynamo" electric motors factory fixed the problems in their repair facilities. Using this experience ZiU engineers corrected the ZiU-5 design, in 1960 new updated mass production series was launched. During mass production some technological adjustments were made, see Variants section. In 1971 ZiU introduced completely new trolleybus design, the ZiU-9. It was more cheap due to technology improvements and refusal from aluminium hull and was able to carry more passengers than ZiU-5. So mass production of ZiU-5 ceased in 1972.