The debacle with TU1-001 led to the development of the class TU2. The class designation suggests it was a completely new design, different from the TU1. But in fact the TU2 was almost an exact copy of the experimental class TU1.
The most important change was - of course - the replacement of the main power generator, which caused so much trouble with the TU1s. For the TU2 a special new type of main power generator was developed. This is the MPT-49/25-3 generator. It has a rated power output of 195 kW and operates at a voltage of 450V with a current of 434 Amp. (maximum 480 Amp.).
Now the diesel engine, the power generator and the electric traction motors were sufficiently balanced:
Note that the weak point in the design is the generator. It is overpowered both by the diesel engine and the traction motors.
Each boogie has two traction motors. The boogies are always switched parallel. When operating normally also the pair of traction motors in each boogie is switched parallel. Each traction motor receives 25% of the power of the generator (49 kW) at the full voltage of the generator (450 V) and 25% of the current (109 Amp.). This allows the speed to be increased to 50 km/h.
For operating at low speeds each pair of traction motors in the boogies can be switched in series. In this case the current running through each traction motor is 217 Amp. and the voltage is 225 V. This means that the full power is available a lower speed. When switched in serie, the maximum velocity is only 13 km/h.
The electric scheme of the TU2.
From the archives of Tarvo Sööt.
Apart from the new generator, the class TU2 also underwent some insignificant modifications to the brake system as well as to the electrical circuits.
The ventilator for cooling the diesel engine and the generator is situated horizontally in the roof of the engine room. This ventilator blows warm air from the engine room high into the air above the locomotive. To insure a good air-flow, large ventilation openings are cut in both sides of the engine room. The ventilation openings can be closed by vertical shutters. When the engine is switched off, the shutters are normally completely closed.
Parameters of the class TU2 diesel locomotive
|
Principal dimensions Length of the body Width of the body Length over the couplings Height above head of rail Base of bogie pins Base of bogies Diameter of wheels Minimum curve radius Total weight Axle-load Gauge |
9.904 mm 2.450 mm 10.740 mm 3.462 mm 5.000 mm 1.700 mm 900 mm 50 m 32 tons 8 tons 750 mm |
|
Maximum speed Cruising speed Shunting speed |
50 km/h 30 km/h |
|
Diesel engine Type Rated power Operating speed Fuel consumption Oil consumption Oil pressure Thrust during start Thrust during operation |
Bernaul 1D12, 12-cilinder, V-shaped 300HP (242 kW) at 1500 r/min 500 - 1560 r/min 60 kg/hour 3,6 kg/hour 6 - 9 atm. 8500 kg 4650 kg |
|
Main power generator Type Power |
MPT-49/25-3 195 kW (450V= x 434 Amp) |
|
Traction motors Number of motors Type Max. voltage Max. current,br> Max. power Wheel formula |
4 TEDa DK806A 275 V= 200 Amp. 55 kW Bo'Bo' |
|
Operational reserves Fuel Oil Water Sand |
700 kg 120 kg 185 kg 200 kg |
A view in the cabin of TU2-244 (Gulbene, 2003).
Photo: Till Puetz.
The first locomotive with this improved design, TU2-001, was constructed in 1955. Like the TU1's, also TU2-001 was tested on the atura testing ring. This time everything functioned as expected. In 1956 the serie production of the class TU2 could be started.
Even after the serie production had commenced, the TU2-001 continued to be tested. It is believed also TU2-002 and TU2-003 were used for this purpose. In 1956/1957 all three locos were brought to the Paneveys network in Lithuania for test runs, probably speed trials. At least it is known that the Paneveys network, with long straight sections and almost no gradients, was used for this purpose when the class TU3 diesel locomotives were tested in 1961.
In the 1960s additional speed trials were conducted in Estonia. Near Pärnu TU2-140 reached a speed of 76 km/h. However the design of the boogies did not permit speeds of more than 50 km/h in normal service. It should be noted that many TU2's would never even run at this maximum permitted speed, because of the poor condition of the tracks of many 750-mm gauge systems.
The boogie of the class TU2, with the integrated buffer, coupling and cow-catcher.
A better view of the TU2's coupling. To the left and the right of the central buffer the coupling chains are clearly visible. The coupling and buffer are mounted directly to the boogie.
After TU2-001 had been built and tested in 1955, the full serie production of the class TU2 commenced in 1956 with engine number TU2-002. Until 1959 a total of 281 TU2s have left the Kaluga machine factory:
| year | running numbers |
number of engines constructed |
| 1955 | TU2-001 | 1 |
| 1956 | TU2-002 - TU2-062 | 61 |
| 1957 | TU2-063 - TU2-145 | 83 |
| 1958 | TU2-146 - TU2-231 | 86 |
| 1959 | TU2-232 - TU2-281 | 50 |
It should be noted that the highest running number known is TU2-276 (until recently: TU2-274). It could not be confirmed that the last 5 engines with running numbers TU2-277 until TU2-281 have really been delivered. If so, they can only have run on isolated and/or unknown industrial or forestry railways.
It is unclear how many TU2s had to be build according to the original plans. If they were intended solely for the Virgin Lands Railways, a total of 100 engines would be a sufficient. But somewhere in 1956 the Soviet government decided that steam traction should vanish from all the Soviet railways as an attribute of the Dark Capitalist Past and an obstacle en route to the Bright Communist Future. This also applied to the narrow gauge lines operated by the MPS. With the new class TU2 diesel locomotives, not only the Virgin Lands railways, but also for existing 750-mm gauge MPS-lines could be dieselised. All TU2s were constructed to the standard narrow gauge for the Soviet Union; 750 mm.
Noticeably it is suggested that in the mid-1950s the Soviet Union would have ordered 200 class TU3 narrow gauge diesel locomotives from CKD in Chechoslavakia. Apparently this order was later reduced to only 45 TU3's. Instead more TU2's from domestic production seem to have been constructed.
Remarkably, we have no record on the factory numbers of the TU2s is missing. Only the factory number of TU2-182 is believed to be known: 588/1958. It could be speculated that, if KM did not build any other types of locomotives during the period the TU2 was in production, and if the TU2s are numbered without interruptions, the factory numbers could be 407 (for TU2-001) through 687 (for TU2-281).
The factory plate of TU2-101 is mounted on one of the boogies. It does not show the factory number; only the type (TU2) and the year of construction (in this case 1957).
Standardised factory plates are mounted on (one of) the boogies. The factory number and the year of construction had to be stamped into these metal plates. In praxis this was (almost) never done or the inscriptions are not visible anymore due to corrosion and/or repainting of the metal.
The 281 TU2s have been built in a period of 5 years with only very few and insignificant changes to the original design. Basically the TU2s may be considered to be all identical when they left the factory. Yet in the course of their career a small number of TU2s underwent some modifications.
Originally the front signal consisted of three headlights of equal size: one left, one right and one above the cabin windows. But sometime in the early 1960s all TU2s running on MPS-lines in the three Baltic states have received a larger headlight above the cabin windows. It was integrated in the body of the locomotive. Estonian engine drivers R. Kaik and V. Filjajev were pioneers of this modification.
TU2-144 is an example of an Estonian TU2 that was equipped with an enlarged integrated front signal above the cabin windows.
Photo: Tarvo Sööt.
Later also TU2s running on different lines in the Ukraine and Russia have been modified more or less in the same way. Though the large third front signal sometimes is just a search-light mounted on the locomotive.
A close view of another type of (home made) large front signal mounted above the cabin windows of TU2-034.
The modifications took place in the course of the years. For instance TU2-034 from Beregovo MPD still had its original modest-sized head lights in 1982, but nowadays it is fitted with a 'search light'. A large number of TU2s have kept their original equal-sized front signals, such as TU2-021, 033, 035, 050, 062, 066, 177, 189, 191, 158, 228, 233, 236, 240 and 264.
A real one-off is TU2-125 alias TEU3-001. This engine has been built only partly by Kaluga and finished by the Kharkov Transport Machine Factory. The body of the locomotive has much rounder shapes than the normal TU2 design. A non-standardised locomotive is really something special in the USSR. But it was intended to be a gift to the Kharkov pioneer railway i.e. it did not work on a MPS-line together with other TU2s. So standardisation was not really an big issue in this case.
TEU3-001 on the Kharkov pioneer railway in 1964.
Photo: P.H. Kiers, collection NVBS.
The Bernaul 1D12 diesel engine has a rated power of 300HP. But when running on full speed (1560 r/min.) a higher power output could be reached. In the early 1960s Tallinn-Vaīke MPD in Estonia had a project aimed at a further increasment the power of the class TU2 to 350HP. The idea was probably to let the traction motors work on their maximum power of 4x 55kW instead of the normal 4x 49kW. It is speculated that this could be achived by further increasing the speed of the diesel motor and thereby increasing the power output of the generator to more than its rated 195kW. This was potentially dangerous for the generator's electrical windings, which could burn due to the increased current. However it seems to have functioned without problems and all 43 TU2s working on Estonian MPS-lines were involved in this project.
The Estonians also experimented with the cooling system of the electrical traction motors in the boogies. For this purpose extra large air collectors were mounted on the roof of the engine room. Four locos were involved in this project: TU2-101, 133, 134 and 143. Apparently the results of the experiment were not as expected, for no further locos have been modified accordingly.
The modificated TU2-101 is preserved in the Lavassare railway museum in Estonia. Externally it can be recognised by the large air collectors on the roof (indicated by the red circles).
The Bernaul 1D12 had a limited life time of only 5 to 10 thousand running hours. This meant the engine had to be replaced by a new one every few years. In the 1980s the Bernaul factory improved its 1D12, increasing the lifetime to 10-20 thousand running hours. The new engines still have to be replaced every 10 years or so. Normally spare parts or a spare motor are hard to obtain after more than 40 years. But in 2003 the 1D12 engine is still in production, so in this case it is not a problem.
Sometime in the 1970s the exhaust-system of TU2-244 was modified. This was clearly visible by the enourmous exhaustion pipes, mounted on the roof on the engine room. The loco was renumbered TU2M-244, with the added M referring to that fact that this is a modified class TU2. However, this was quite confusing, since the class designation TU2M was already in use for an industrial narrow gauge diesel locomotive type.
After 1993 the TU2s from Paneveys MPD in Lithuania have received large cylinder-shaped silencers on both exhaustion pipes. This is known with engines TU2-052, 089, 090, 094, 133 and 150.
The TU2s were initially intended for the Virgin Lands Railways. And indeed most of the locomotives produced in 1956-1957 were assigned to the Juno-Ural (South-Ural), Orenburg, Tselinograd and Karaganda regional railway departments, which operated the Virgin Lands railways.
From the 61 TU2s produced in 1956, 54 examples went to the Virgin Lands Railways in northern Kazakhstan and southern Russia. In 1957 this figure went down to 45% and in 1958 only 24% of the produced TU2s went to these railways. In the end a total of 110 TU2s have been supplied to the Virgin Lands railways in Kazakhstan and Russia. This is 39% of the total production.
The other 61% of the TU2s found their way to other narrow gauge railways. In 1957 Estonian, Lithuanian and Russian narrow gauge systems - other than Virgin Lands Railways - also received sizable TU2 allocations. In 1958 the deliveries to Russia continued whilst TU2s now also went to Latvia and the Ukraine. Finally, in 1959 the TU2s were supplied to Estonia, Russia and the Ukraine.
The above figures apply to those locomotives whoms allocations are known. Remarkably, one third of the TU2s produced in 1958 have never been accounted for. Even less is known about the faith of the TU2s from 1959, of which 44% went to unknown destinations. They have probably been delivered in small batches or as unique examples to different forestry and industrial railways, such as the case with the few known TU2s from 1959. For instance TU2-264 went to the Järvakindi glassworks (Estonia), TU2-266 and 268 to the Teresva forestry railway (Ukraine), TU2-269 to the Kotrbulak metallurgical combine (Kazakhstan) and TU2-246 and TU2-276 to an unknown line in Central Asia. Also some MPS-lines received additional TU2s from the 1959-production (TU2-252 MPS Liepaja, TU2-263 and 274 MPS Gajvoron). It will probably never be possible to account for the remaining the TU2's which have been supplied to unknown, isolated and/or remote industrial systems.
First allocations of the class TU2 (country-wise)
| Year of construction | 1955 | 1956 | 1957 | 1958 | 1959 | Total per country | |
| Kazakhstan | 41 | 28 | 18 | 1 | 88 | 31% | |
| Russia, Virgin Lands | 14 | 8 | 4 | 26 | 9% | ||
| Russia, other lines | 1 | 10 | 21 | 13 | 44 | 16% | |
| Estonia | 21 | 1 | 10 | 32 | 11% | ||
| Latvia | 1 | 9 | 2 | 12 | 4% | ||
| Lithuania | 9 | 9 | 3% | ||||
| Ukraine | 1 | 9 | 8 | 18 | 6% | ||
| (thusfar unknown) | 1 | 5 | 5 | 24 | 16 | 51 | 18% |
| Total per year | 1 | 61 | 83 | 86 | 50 | 281 | 100% |
At least until 1991 all TU2s had this inscription beneith the door. Above the sign it says SSSR (or CCCP in Cyrillic charcters; meaning Soviet Union) and below the sign the railway region it belonged to. In this case it says Od. .D., meaning "Odessa Railway".
Photo: Mehis Helme.
In 1957/1958 many TU2s originally allocated to Virgin Lands Railways have been transferred away to other lines. These TU2s were mainly reallocated to the Zabaikal railway in eastern Siberia as well as to Estonia. It had no negative influence on the Virgin Lands Railways, because the number of TU2s required seems to have been grossly overestimated. This is partly due to the fact that not all projected narrow gauge lines have actually been build and that some lines have been erected in broad gauge instead.
A second migration wave occurred in 1972. The Zabaikal railway in Siberia (Margutsek MPD) had been converted to broad gauge and its enormous TU2-fleet was send back to Europe, mainly to MPS-lines in the Ukraine (Gajvoron, Beregovo, Antonovka). At the same large quantities of TU2s were reallocated from the Baltics to the Ukraine (predominantly to Vapnjarka). Also many TU2s from the Baltics found new employment on pioneer railway all over the Soviet Union.
On forestry and industrial systems the TU2s have never been very successful. Especially their axle-load of 8 tons made them unsuitable for the light tracks of forestry railways. After the class TU4 had been taken in production (in 1969), these TU4s replaced the TU2s. But on MPS-lines the class TU2 remained the backbone of the locomotive fleet.
The first - and thusfar only- type of diesel locomotive which could compete with the class TU2 on MPS-lines is the class TU7. In the 1980s and early 1990s an attempt was made to replace the TU2s by these TU7s. But due to the poor quality of the class TU7, it could only replace the TU2s on the MPS-systems of Gulbene, Tumskaja, Vapnjarka and Shilda.
The number of TU2s used in daily operation on MPS-lines has decreased dramatically after the economic crisis and the line closures following the revolutionary events of 1991. Less locomotives were needed and many TU2s could be dumped. From the TU2s working on MPS-lines in 1991, almost all engines had been dumped 10 years later. Most TU2s have been scrapped. The only systems that have kept using TU2s for scheduled services are Beregovo, Antonovka, Gajvoron and Atbasar. Later also Gulbene started using class TU2s again, alongside the TU7s. Furthermore the ex-MPS network based at Paneveys has a dozen of TU2s, though this railway is not used for regular passenger and freight traffic anymore. Nowadays the majority of the active TU2s are working on pioneer railways instead of on former MPS-lines.
Today approximately 95 TU2s are still in service or at least preserved. This is 34% of the original fleet. A roster of the surviving TU2s is published on a seperate page.
The original standard livery of the class TU2 is dark green with a thin yellow stripe under the cabin windows and on the sides of the engine. A red communist star was mounted on the front of the cabins, under the windows. This star was accentuated by three thin yellow stripes. Later many TU2s have received an additional yellow stripe on the bottom of the body. In the course of the years, the colour of green used to repaint the TU2s became brighter and brighter.
TU2-009 in the standard green livery, seen in Vapnjarka in 1982.
Photo: Mehis Helme.
In the 1970s and 80s Gajvoron MPD further modified the livery of its TU2s. On the fronts of the locos, the bottom striping was often widened and even sometimes painted in orange instead of yellow. Around 1990 Gajvoron MPD started to add diagonal striping (red or yellow) on the fronts of the cabins, accentuating the red star even more. Such striping has also been observed on some TU2s from Paneveys MPD.
On MPS-lines, green has always been the predominant livery. Yet, also light blue TU2s could be observed all over the Soviet Union. Such TU2s had been overhauled by one of the main repair workshops in Gajvoron and Orenburg. Normally, after a few years they were repainted green again in their own depots.
TU2-274 in the light blue livery of the Gajvoron main repair workshop, seen in Novopoltavka on 24 May 1998.
Photo: Karl Landskröner.
The TU2s working on the other (former) MPS-lines have remained green of light blue, though the green colour used in Gajvoron and Antonivka is much brighter than the original. Soon after the revolution of 1991, the communist red star was removed from the front of most locos working on MPS-lines. In 2003 only TU2-071 and TU2-179 from Gajvoron MPD still have their star. Noticeably TU2-179 is the very last TU2 still painted in a more or less original green livery with a red star.
The TU2s working on pioneer railways all have different liveries, the one even more 'creative' than the other. The TU2s delivered to the pioneer railways by Kaluga already had unique liveries from the beginning. See Sutyagin Dmitry's site for original color schemes of TU2s working on pioneer railways. According to Sutyagin the livery depended on local traditions, available paint and taste of house-painters. Later, second-hand TU2s taken over from regular MPS-lines were normally repainted before being taken into service on pioneer railways. Remarkably, most pioneer railways did not remove the red communist stars from their TU2s.
