ZiU-9

ZiU-9 (in Russian ЗиУ-9) is the Soviet (and now Russian) trolleybus vehicle. Another names and indexes for the same vehicle include ZiU-682, HTI-682 and XTU-682 (respectively ЗиУ-682, ХТИ-682 and XTU-682 in Russian designations). The ZiU acronym stands for "Zavod imeni Uritskogo", which means plant named after Moisei Uritsky, the Russian revolutinary. Before 1996 thisacronym was also a trademark of vehicle producer, now it has been changed for "Trolza". The ZiU-9 was put in mass production in 1971 and it is still assembled now amongst other more advanced trolleybus vehicles on the Trolza (former ZiU) factory. Total number of produced ZiU-9s exceeds 40,000 vehicles, this model is the most numerous trolleybus vehicle in the world.

History and development

The explosion-like development of trolleybus systems in Soviet Unionin 1960-ies required a large number of trolleybus vehicles. The mainstayof contemporary Soviet trolley fleet, the ZiU-5, was not sufficient for huge urban passenger transfers; it was more suited for medium-size cities rather than large megapoleis such as Moscow or Saint Petersburg. In addition the ZiU-5 had an aluminium hull, which was expensive and complicated from technological point of view. The two doors in the ZiU-5 hull ends did not work well in overcrowded situations which were quite common in Soviet public transport.

The ZiU-9 was a quite successful attempt to solve this problems. It hasone extra door in comparison with ZiU-5. Two doors are wide and placed in the middle and rear end of the vehicle hull. One small door in the front end of the vehicle was/is comfortable for the driver and for outcoming passengers. The hull of ZiU-9 is welded steel one and it is significantly cheaper and simpler in production than the hull of ZiU-5. The external appearance of ZiU-9 was influenced by contemporary German-made MAN trolleybuses.

However the electric equipment of ZiU-9 had minor changes from ZiU-5, only the power of main motor was increased. The indirect resistor-based control system of electric current was slightlymodified to deal with the increased power of the main motor. While western designers developed new semiconductor-based control devices, Soviet engineers decided to leave the old resistor-based system for service simplicity. First prototype vehicles were tested in Moscow in 1971 and were approved for mass production after minor design adjustments.

The '9' number in vehicle name was the initial project index of the design team.However after launching mass production the new trolleybus received new index '682' from united classification of non-rail public transport vehicles. So all series vehicles had ZiU-682 designation. But the 682 number is difficult to pronounce and the shorter '9' still lives in everyday language of drivers and servicemen. In 1986 the new classification was introduced where former ZiU-682 was designated as HTI-682. But this was not an end of renaming the same vehicle. Russian acronym HTI writes in Cyrillic alphabet as ХТИ and this three Cyrillic letters in 1995 were confused with Latin letters XTU. The last Latin acronym became an official name of the vehicle.

Modifications

During mass-production there were some improvements of ZiU-9 design. Anymajor change is designated by letter after '9' or '682' index:

* (1971) ZiU-9 - first prototype vehicles
* (1972) ZiU-9B (ЗиУ-9Б) - first large-series vehicles
* (1976) ZiU-9V (ЗиУ-9В) - major improvements in electric equipment
* (1992) ZiU-9G (ЗиУ-9Г) - door gear was replaced from electric to pneumatic, the vehicle frame was lightened, so the active service life became shorter.

This variant is in mass-production now, it is a most cheap trolleybus indomestic market of Russia. Full official name with minor improvementdesignations is XTU-682ГОЕ-012.

Many factories in modern Russia or Belarus developed their unlicensed or semi-licenced copies of ZiU-9 design. They may have different designations and trademarks, but in colloquial language all of them referenced as "ZiU-9 clones".

Operators

ZiU-9s worked or are now working in all ex-USSR countries except Baltic states. They were also sold to Greece, Argentina, Colombia and former Eastern Bloc countries. Three cars were on loan in 1973 for testing purposes in Helsinki, Finland. In 2004 the ILPAP, the operator of trolleybusses in Athens, Greece donated nearly all of its old ZiU-9 trolleybusses to the city of Belgrade, one was donated to the East Anglia Transport Museum.

External links

* [http://tramnn.narod.ru/misc/trolley/gall.html ZiU-9 on the Nizhny Novgorod tram site] (in Russian)