The Konstal 105Na are a class of Polish trams manufactured from 1979 to 1992 in the workshops Konstal Chorzów, Poland. The metre-gauge version is designated as 805Na. As of 2016 they were still the most common trams in Poland.
105Na is unidirectional motor tramcar, equipped with four doors.
It is a development of the earlier Konstal 105N. The main changes being a shift in the location of the electrical equipment from under the steps to the back wall of the driver's cabin, the introduction of a separate cabin for the driver, as well as the removal of the small windows under the front and side windscreens. The most important change was the introduction of motor grouping, which reduced the energy consumption by 12%. During initial acceleration, the four motors are connected in series, whilst at higher speeds, two groups of motors are connected in parallel.
While in service, the 105Na vehicles were the subject of various modifications and upgrades (including changes in the electrical system, new front plastic, change of the door opening mechanism, and even re-design, for Poznaà Â, to the bidirectional Konstal 105NaDK). Almost all 105N cars in Poland have over time been modernised to the 105Na standard.
The Konstal 105Na and 805Na trams provided the basis for the production of a large number of prototypes and variants:
The number of standard-gauge version 105Na vehicles produced is 1443 while the number narrow-gauge version, the 805Na, is 691.
These trams were used in all Polish cities which operate a tram system and they are the largest group in the stock.