In the mid 1920’s, during the so-called “new economic policy” (NEP), a gradual recovery of the industry, devastated by the First world and Civil wars. The most rapidly developing industry in Moscow, which became the capital of the USSR. In this regard, the sharply increased load on public transport, in those years, mainly the tram who had to carry passengers from the residential areas of the city to businesses and back.

Partly solved the problem of the decision to design and begin to produce so-called “standard” two-axle wagons. However, the experts were clear that two-axle wagons is unlikely to live up to them hopes to curb the rapid passenger traffic. Moreover, some cities were located not on the plains, and a two-axle motor cars, with great difficulty, pulled into a mountain wagon trailers.
At the same time, large cities such as Moscow and Kyiv, already had considerable experience of operation of four-axle tram cars. Therefore, in parallel with standard two-axle cars, it was decided to design and produce a four.
The task of creating a four-axle cars were delivered before the Kolomna machine-building plant. Already in 1926, he released two such motor car, which was sent to Moscow for trial operation. Given that the trams were designed for use on suburban lines with increased speed, motor cars planned to be equipped with current collectors pantograph type. However, the pantographs either because of imperfections in construction, or poor maintenance worked poorly, and the serial trams were replaced by more simple – rope.
In 1929, after the completion of the trial operation of new four-axle tram cars, has begun serial production of cars type KM (Kolomna Motor) and on Kolomna at the Sormovo factory.
Carriages of the KM were, in fact, the four-axle version of the X-series trams, which were built in the same period in Mytishchi railcar plant. They were two-sided, with doors on both sides of the carriage, and control stations were equipped both on the front and rear sites, which allowed the trams to do without spinning off at the last stop.
The body of the wagon of the KM series was a mixed metal-wood construction; he relied on a two-axle truck with sheet riveted frames. Each pair of wheels were driven by electric motors PT-35 with the supporting-axial suspension. Governed motors controllers DT-41. Interestingly, due to the low level in the domestic electrical industry, the time the first trams of the type KM, set in Moscow, not equipped with traction equipment and originally was used as a trailer and the engine of their converted tram depot. Each of the cars were equipped with pneumatic and manual drum brakes.
In Leningrad, the cars of type KM was used as trailed in the non-motorized version
In Leningrad, the cars of type KM was used as trailed in the non-motorized version
On the roofs of the trams of the KM series, however, as on the roofs of the other carriages used in Moscow, sets the signal lights-spotlights, denotes the ends of the car lights red. How these spotlights were so that they are simultaneously illuminated, and route signs.
Beginning July 1, 1934, the lights began to designate the routes of the tram. This spotlight is equipped with colored glass to use combinations of their colors to indicate routes, as has been done in Leningrad. In contrast to the Leningrad system in which a route number designated by the combination of two colors, in Moscow, the color of the soffit designated numbers the route number according to this scheme:
1 – red, 2 – blue, 3 – green, 4 – yellow, 5 – olive, 6 – purple, 7 – blue, 8 – brown, 9-lunar-white, 0 – transparent glass.
Thus the right facing the lamp marked “tens” and the left”units.” Lettered routes A, B and C are marked by the combinations of colors, to correspond with the numbers 91, 92 and 93, respectively. The staff of cars R I N the spotlight was left red.
Trams of the type KM, as it turned out, had sufficient traction to be used in the coupling with two-axle trailer cars of type M or S.
Trams of the KM series delivered not only in Moscow but also in Sverdlovsk, Gorky and Leningrad. The latter has received 12 of the 20 cars ordered, which was designated to “St. Petersburg” style – MM (Motor, Moscow). Of these twelve cars, five worked as tow, and the others collected the first experimental carriages of the MA/PA.
In a number of other cities were already worked in Moscow trams of type KM. In 1941 part of the trams were evacuated – 21 car was in Kuibyshev and nine in Kazan. Some trams were sent from Moscow after the war, replacing them with the new series of MTV-82.
In 1950-ies of the cars of type KM, worked in several cities of the USSR, handed over to the city of Gorky, where they were carrying passengers until 1970. In Moscow itself, the trams of type KM he worked until 1974, and copied them, not because of physical deterioration, but as obsolete. To replace them were purchased by the Czechoslovak trams T-3.
General view and main dimensions of the motor of the tram car type KM
General view and main dimensions of the motor of the tram car type KM:
1 – route light (Sofit); 2 – ventilation air intake; 3 – starting resistors; 4 – collector; 5 – doors; 6 – safety mesh; 7 – compressor; 8 – truck; 9 – coupling; 10 – trip index; 11 – lamp; 12 – connecting receptacle connector; 13 – a hose coupler air brake system

Motor car type KM 1929 - 1935
Motor car type KM 1929 – 1935
Motor car KM with trucks 1ДС
Motor car KM with trucks 1ДС
Pritsepnoy wagon, manual, 1930 - 1935
Pritsepnoy wagon, manual, 1930 – 1935
The layout engine of the car AWAY
The layout engine of the car KM:
1 — entrance door; 2 — column manual brakes; 3 — faucet air brakes; 4 – controller; 5 – the driver’s seat; 6 – bench; 7 – cabin door
Trailer car type KP

Trailer car type KP
The upgraded car type KM in the city of Chelyabinsk
The upgraded car type KM in the city of Chelyabinsk
In the process of operation of tram cars of type KM have revealed their essential design miscalculation-the lack of strength of bogie frames, resulting in occurrence of cracks in the sidewalls and beams, and in some cases to fracture of beams.
In 1945 Sokolniki car-repair plant (SVARZ) have designed and began to produce two-axle trucks of the type 1ДС a fundamentally different design – they have been strengthened, with a more elastic spring suspension and engines of increased power type of DTI-60. These trucks were rolled under the carriages of the KM instead of the regular ones. Initially, in 1945, the new trucks in the experiment was equipped with several “CMOV”, and since 1947 truck replaced almost all the cars. As it turned out, new suspension significantly extended the life of the trams of type KM.
The list of upgrades that have been trams in operation, not limited to one only by the replacement of trucks. In Moscow almost all the routes that went tram cars KM, at the last stop had the reversals, and therefore, when the factory repairs of the wagons were sewn all left doors to eliminate control on the rear platform, and on the front was fenced off from the platform partition. The door was equipped with a pneumatic drive, and the windshield pneumatic wiper. Such alterations of the tramways of the type of KM was subjected to further not only in Moscow.
In addition to problems with carts other troubles technical sense with the trams of type KM, apparently, has not happened. Against everything else, they were incredibly reliable and tenacious.
In 1930, the Kolomna factory ceased production of motor tram cars of the type KM and began to produce trailers of the type KP. Sormovsky plant has continued to produce KM until 1935.
Trams of the type of KP that are designed to work in tandem with a motor tram cars of type KM, was not too similar to them. First of all, the cars of type KP had doors on one side only, since the coupling of motor and trailer cars can not be operated without turning on the Terminus.
In addition, the operating experience of motor cars such as KM showed that in the elongated salons significantly impeded the progress of passengers from the entrance to the exit. Taking this into account, as well as the experience of the four-axle trams of type MAN, the car is KP designed the three-door. Place the conductor in-drawn carriages located in front of the entrance and the direction of the flow of passengers, it was assumed that the entrance to the middle door, exit in the front and back.
Trailer cars of the KP really helped to solve the problem of increasing traffic volumes, but they had one very serious design flaw. It was the fact that the frequency of oscillation of the car with a spring suspension when driving in normal mode sometimes coincide with the resonance. As a result, the carriage being empty, or half empty, when riding begins, up to the derailment, wobble.
Frame of trolleys of KP were performed with stamped sidewalls. However, the strength of the frames is not added.
A large part of trams of type KP were delivered to Moscow. The rest came to Kharkov, Arkhangelsk and Sverdlovsk. In 1944, part of the cars of type KP sent to Pskov to restore destroyed by the Nazis tram system. However, it was subsequently decided to restore the tram in Pskov, Pskov and all trams KP sent to Riga, where in 1948 – 1952 they were completely rebuilt by local tram control. Their truck was equipped with an electric motor instead of standard body made completely different. Rebuilt so motor cars received the designation RT-48.
The cars of type KM, which had a length 12 550 mm width 2140 mm, was not overly roomy for the four-axle trams. In fact, the benefits of a four-axle undercarriage in the case of KM was used irrationally. But do not forget about to work in any conditions, developed these trams. They had to walk the tracks running through the old, narrow streets. Way on these roads had to be laid too close to each other, with bends of large curvature. So the designers designed the car KM very narrow, with short overhangs.
The advantages of the four-axle wagon crew was there. Short base truck (1750 mm vs 2,700 mm at the car of type X) allowed the trams of the type of KM is easy to fit in any curves without significant wear of the ridges of the wheels. At the same time, long total base (5850 mm against the same 2700 mm car X) and short overhangs (2885 mm 3785 mm in car X) helped to improve the smoothness of the car on the straight parts of the road. As a result, the cars of type KM developed more speed and less worn tram tracks. An important circumstance was that the four-axle wagon, which had twice the driving axles than biaxial, can develop more thrust.
Technical characteristics of tram cars types KM, KP
In the mid 1930-ies the production of tram cars KM and KP for several reasons stopped. First, Kolomna plant was reoriented to the steam locomotive, and Sormovsky -on shipbuilding. Second, the cars KM and KP, corresponding to the technical level of the 1910-th years, by the mid-1930s already obsolete. Just at this time in the United States appeared very good cars such as the RCC, which became the object of imitation throughout the world. Thirdly, in cars such as KM had serious problems with carts. And fourth, Moscow, the main customer of tram cars of type KM and KP, in the 1930-ies seriously reconstructed – the widened street, and the tram lines were replaced by trolley and bus. And in 1935 appeared in Moscow metro. Accordingly, the demand for trams has decreased.
In this regard, many tram cars were written off and cut into metal in Moscow, however, still preserved tram, consisting of electric motor car type KM No. 2170 and trailed type KP No. 2556. The tram is in quite a healthy state and is often used in film productions. The most known movies with its participation – “the meeting Place cannot be changed” and “the Pokrovskie gate”. Another motor car type KM No. 162 in the operating state is preserved in Nizhny Novgorod. Interestingly, at the Nizhny Novgorod car original truck.


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