From the history of the tram car. The fact that on the tram lines of the country “standard” rolling stock occupied by the end of 1930-ies a dominant position, does not mean that he was free of flaws even for its time. First and foremost, experts have noted excessively large (14.5 tons) mass of motor cars of type “X”, which, being generally crowded with passengers, caused increased consumption of electricity. This dramatically inferior in dynamic characteristics surrounding them more intense flow of road transport, loud and unpleasant noise when driving, and quickly destroyed the railway track already laid in most of cities, buildings, that is, on the live thread. The elimination of the second control stations and door openings of the left side eased “Kharkiv” rather little, as it simultaneously had to introduce pneumatic actuator doors, the driver’s cabin and other improvements dictated by concern for safety.
Many problems are caused are also the manufacturer of one of the most critical parts of the car — two-axle truck. The length of her frame was 2.8 m, and at Mytishchi plant simply was not the press, is able to forge such a large billet. So the workers, heating of the gas burners half of the future side of the truck, brought it in a press and stamped to the vertical axis of symmetry, and then manually unfolded the heavy disc, and it started again. Such imperfect technology, of course, the most lamentable way affect the quality wagon frames, leading to their frequent breaks. Besides, to ease cart and provide access to its internal equipment, the side stamped several holes, which often began soon to flee the treacherous cracks. Trying to get rid of these shortcomings, the Kiev factory in the 1930-ies he started to make the sides of the solid sections, but it is even more weighted the truck and car.
Then, preparing to celebrate the 40th anniversary of the Kiev tram, engineers Babuha, Olshansky, Pigin and Seregin decided to remove all these drawbacks by… a complete renunciation of the truck. Wheelset their experimental car No. 901 hung directly to the frame — like trailers, “M”, to which bottom is attached well as traction motors and brake equipment. This decision allowed us to significantly lighten the car, well, inconveniences in terms of repair to a certain extent offset by the increased reliability mastered by the time the factories-suppliers electro-and pneumatic units. Another important improvement carried out by the same engineers, was the equipping of a four-car wide doors and smooth, with no intermediate thresholds and partitions with sliding doors floors. This significantly accelerated landing-landing in rush hours, and to increase the total capacity.