Before continuing the story about the creation of the medium tank T-62, it is necessary to make a

short excursion into history and outline the state of tank production in the USSR in the first post-
war decade, in particular, using the example of plant No. 183. In our opinion, this will allow us to
better understand the reasons for the failure with the promising tank "Object 140", as well as to
evaluate the efforts of the industry management and the design collective of the plant, which
eventually led to the creation, by trial and error, of the best-in-class combat vehicle.
The struggle for the future
During the Great Fatherland’s War in the Soviet tank-building industry, the main attention was paid
to ensuring a steady increase in the volume of production of combat vehicles. The experimental
design works (EDWs) was carried out according to the residual principle, in the conditions of
almost complete absence of experimental production, testing benches and factory proving grounds.
Only in September 7, 1949, in accordance with the decree of the Council of Ministers of the USSR
No. 13906rs, a special design bureau for medium tanks (SKB-183) with an experiment capacity was
organized from the tank design bureau of plant No. 183. By Order No. 427-o of September 17,
1949, 79 engineers and technicians were sent to Nizhny Tagil to staff the new SKB. However, by
January 1, 1950, only 20 people arrived at the plant, including 14 military engineers graduated from
the Military Academy of Armored and Mechanized Troops of the RKKA named after I.V. Stalin.
Through the year, the team of SKB-183 was supplemented by several more young specialists whom
graduated from civil higher and secondary educational institutions. Though they did not yet
possesed sufficient experience in the design or production activities. And the outflow of
experienced cadre tank designers from Nizhny Tagil continued. But aside from the question
personnel, the question of building an experimental capacity was acutely felt.
By the mid-1950s, the question regarding the need to strengthen the experimental bases and design
bureaus of tank industry factories reached the governmental level. The main problem lies in the
exceptionally protracted process of experimental vehicle trials: the design of fighting vehicle
complexity was constantly increasing, and further improvement became impossible without
conducting a large volume of research on the most diverse topics beforehand.
The situation considered to be so critical that it required the intervention of the First Deputy
Minister of Defense of USSR Marshal G.K. Zhukov. Georgy Konstantinovich, in his letter No.
1332174 dated April 2, 1954 to the Deputy chairman of the Bureau of Mechanical Machinebuilding
at the USSR CM, Yu.E. Maksarev, expressed the need "... to assist in the quick and positive solution
of issues related to the expansion of the Design Bureau, strengthening experimental capacities at
industry’s plants...".
A more detailed and thorough view of the problem was presented on April 20, 1954 by the chief of
the Armored Forces, Colonel-General A.I. Radzievsky in his address to the Minister of Transport
and Heavy Machinebuilding (MTiTM) I.I. Nosenko: "... To accelerate and improve the development
of new tanks, self-propelled guns, armored personnel carriers, engines and components, I consider it
necessary:
1. To create a scientific experimental capacity at plant No. 75 for development of the Charomsky
turbocharged piston engine for a medium tank.
2. To create a scientific experimental capacity at the Kirov plant in Leningrad for the development
of a gas turbine for a heavy tank.
3. Expand the experimental design capacities for tank building at the factories: No. 174, Kirovsky in
Chelyabinsk, Kirovsky in Leningrad, No. 75 MtiTM.
4. Expand the experimental-design and experimental-production capacities for engine building at
the Kirov Plant in Chelyabinsk, plant No. 77 in Barnaul, Turbo Engine plant in Sverdlovsk MtiTM.
5. Expand the VNII-100 MTiTM and provide it with production facilities and the necessary
equipment.
These measures require their immediate practical resolution, since without their implementation in
the very near future, further development of experimental tank building is impossible."
Note that in these proposals, plant No. 183 was not even mentioned. Probably, after the release of
A.A. Morozov from the duties of chief designer, this enterprise was no longer considered by the
military leadership as a developer of new models of medium tanks. And the special climatic
conditions in Nizhny Tagil didn’t particularly contribute to attracting qualified specialists. For
example, in 1951-1954 77 young specialists were sent to SKB–183, while 68 people resigned in the
same timeframe.
The remoteness of plant No. 183 even from the city of Nizhny Tagil itself (by 14 km), the absence
of any factory cultural institutions, insufficient medical care, an underdeveloped retail network and
the lack of material commitment of specialists also did not contribute to attracting personnel, and
consequently, to the professional technical growth of the plant's design collective.
Of course, the ministry took all possible measures to create more favorable conditions for the
designers of the SKB: the company was allocated more personal salaries compared to other
factories, officers seconded from the Soviet Army and young specialists were sent to it. However,
all this did not radically improve the situation in the SKB and at the plant. In order to change the
current situation, L.N. Kartsev put forward those proposals:
"1. Increase the staff of KB to 300 people.
2. Increase the staff of the experimental workfloor in terms ETWs* and employees to 200 people.
3. During 1955-1956 send 120 engineers graduating mainly from Ural higher educational
institutions. Especially from the UPI, 75 of which in 1955.
4. To organize from the 1955-1956 academic year in Nizhny Tagil on the basis of the evening
branch of the UPI day and evening tracked vehicles specialty faculties.
5. To leave 12 officers seconded at the plant – graduates of the Academy and to over the next three
years second 30 graduates,by 10 each year.
6. To complete and equip an experimental workfloor in 1955, for which purpose to allocate 5
million rubles, as well as to build a tankodrome.
7. Allocate 500 thousand rubles for the laboratory and the equipment of the Design Bureau by
targeted assignment through low-limit allocations.
8. To establish for designers and researchers a official salaries schemes of the aviation industry
Design Bureaus (Tupolev, Lavochkin).
9. To allocate the target assigments for personal premiums to the most deservedly qualified
employees of the Design Bureau and the experimental workshop.
10. Introduce a premium system which depends only on the implementation of the Design Bureau
plan, regardless of the implementation of the plant plan.
11. To complete the Palace of Culture in 1956."

The appeal of the young chief designer of plant No. 183 did not go unnoticed by experienced
functionaries of the 1st Main Directorate of the Ministry of Transport Machinebuilding. The post of
head of the department was then held by the former chief engineer of plant No. 183 N.A.
Kucherenko.
In accordance with the instruction of the Deputy Minister of Transport Machinebuilding S.N.
Makhonin No. M-1684 dated March 12, 1956, the VNII-100 commission arrived at plant No. 183 to
assess the state of work on tank topics. Commision stated the imperfection of the existing
organizational structure of the enterprise, which did not allow providing "a single purposeful
leadership of experimental sub-divions." The erroneous planning system of trial-experimental work
of Shop 540 and low production discipline were noted.
According to the specialists of VNII-100, "shortcomings in the organizational structure and
planning in the experimental workshop 540, as well as the irresponsibility of serial workfloors in
terms of ensuring experimental pilot production, significantly hinder the conduct of trial-
experimental work at the plant, both in terms of manufacturing experimental parts and assemblies,
and in terms of timely conducting the trials ... Technical culture of tank trials at the plant is at an
insufficient level."
As suggestions, it was recommended to change the subordination of experimental workfloors
adopted at the plant and the procedure for planning EDW*, to build a powerplant testing bench and
develop a laboratory for special measurements, staffing it with "sufficiently experienced ETWs and
workers."
In general, the result of the discussion of the problem raised by the appeals of G.K. Zhukov and A.I.
Radzievsky was reduced to the general considerations of the head of the 1st Main Directorate N.A.
Kucherenko in his letter No. 1/006436, sent on December 4, 1956 to the Ministry of State Control
of the USSR. Without denying the obvious fact of the weakness of the experimental bases of the
plants, he noted his diligence in developing and approving their construction projects, while
lamenting about the lack of necessary funds.
Kucherenko confirmed the lack of groundwork for new designs and assemblies of a vehicles,
which, in his opinion, which significantly complicated and delayed the creation of new objects: "In
such a situation, when alongside of creating tank all its main assemblies are being created anew , it
is very difficult to ensure the execution of work in a short time, especially to ensure serious
refinement and fine-tuning of all assemblies of the vehicle". Kucherenko especially precisely dwelt
on particular detail on the work of the tank design bureau of plant No. 75:
"As a rule, tank design bureaus annually receive a large number of different tasks for EDWs.
So, for example, in 1956, the tank Design Bureau of plant No. 75 (C. Morozov) carries out the
following works:
- creation of a new medium tank;
- creation of thermal smoke equipment for tanks;
- development of a set of equipment to ensure underwater movement of tanks;
- creation of anti-atomic protection for medium tanks;
- development of the design of flotation kit for the T-54;
- working out the technical documentation of the T-54 tank and the K-67 bridge-laying vehicle
during the serial production of these vehicles...
...In addition to increase of number and qualifications of designers to ensure the creation of new
samples in a shorter time, it is advisable to reduce the number of topics simultaneously carried out
by design bureaus."
As a simplification measure of "complex system of creating new samples," Kucherenko proposed
to simplify it by, "in particular, to cancel the stage of consideration of the technical project." One of
the disadvantages, he considered significant differences in the tariff rates of designers at the
factories of the chief commitee: "... In remote areas, for example, in Omsk at plant No. 174, salaries
are lower than in Kharkov and Leningrad." In addition, "... the official salaries in the Design
Bureaus of other ministries, for example, the MOP (MAP), engaged in the creation of samples of
military equipment are significantly higher than the official salaries in the MTrM Design Bureaus"
Kucherenko in his letter noted that "... the main components of the experimental samples are
manufactured, as a rule, in serial workfloors overloaded with a serial program, which lengthens the
production time of the vehicles. The absence of the necessary testing benches and other equipment
leads to the fact that the inspection of the assemblies is carried out on the finished vehicle, while it
takes considerable time to eliminate the shortcomings and as such assemblies tuning or manufacture
of new assemblies.
The duration of the experimental samples production is also associated with a delay in the delivery
of purchased products by related ministries: guns, stabilizers, rangefinder sights, etc."
Meanwhile, in parallel with the refinement of the design of the experimental tank "Object 140",
SKB-183 focused on the incremental implementation of new assemblies and components into the
design of serial machines. This made it possible to continuously improve their design, increase
combat capabilities while at the same time gain invaluable experience that could be used during
research on prospective combat vehicles . At the same time, young specialists consolidated their
knowledge and acquired much-needed professional skills.
At the Plant No. 183 (designers) continued to engage in improvement of the design of serial T-54A
and T-54B* in the direction of increasing the power of armament, improving stabilization,
increasing ammunition compliment, introducing night observation and sighting devices, etc.
The first experience of placing more powerful armament on the T-54 in the SKB-183 was obtained
all way back in 1953, having developed under the leadership of A.V Kolesnikov, a experimental
medium tank "Object 141" with a new D-54 tank gun (muzzle velocity of an armor–piercing
projectile is 1015 m / s) installed in a modified turret. In 1954, the "Object 141" was manufactured
and factory trials were successfully conducted. However, the proving ground-military trials of the
tank conducted in the period 1955-1956 revealed the need to refine the two-plane stabilizer of
weapons installed on the tank. Works in this direction continued to be applied now to the serial
T-54A .

* T-54A ("Object 137G") – an experienced tank with an armament stabilizer in the vertical plane of
the TSNP-1 "Gorizont" and an automated electric turret drive the TAEN-2 "Voskhod"; adopted by
the Soviet Army by Resolution of the Council of Ministers of the USSR No. 420-260 dated March
8, 1955. T-54B ("Object 137G2") is an experimental tank with a two–plane armament stabilizer of
the TSPN-2 "Cyclone"; adopted by the Soviet Army in accordance to Resolution of the Council of
Ministers of the USSR No. 1118-581 of August 15, 1956.

In accordance with the directive of the Deputy Minister of Defense No. 727377 of May 22, 1956,
dated January 19 to April 15, 1957, trials of the three experimental samples of T-54A which
received designation "Object 139" (developed in 1955-1956), were conducted at the GNIAP GAU
from January 19 to April 15, 1957. lets examine those more closely since the results are directly
related to the design of prospective tanks.
A new 100-mm D-54TS tank gun with an muzzle velocity armor-piercing projectile of 1015 m / s
was installed in the "Object 139" (this artillery system was envisaged for use in the medium tanks
"Object 140" and "Object 430") and a two plane gun stabilizer "Molniya" with a periscope sight
T2S "Udar". The turret differed from the base by the reduced height of the frontal part and
embrasures of the cannon and the coaxial machine gun, as well as by the diameter increase of the
turret ring by 68mm (measured by internal clearance). A new turret drive mechanism with a
backlash-controlling device in the gear and a rotating floor of the fighting compartment was used.
The fuel system has undergone changes – fuel tanks-ammo racks have been introduced and the fuel
capacity has been increased by 40 liters.
The designers understood that the simultaneous implementation of all planned innovations would
naturally lead to an increase in the combat weight of the base model T-54A. Therefore, in order to
keep it within the required 36 tons, they had to reduce the thickness of the hull side plate by 10 mm
(from 80 to 70 mm) while maintaining the external dimensions of the hull. One of the conclusions
based on the results of the proving ground-troops trials of the "Object 139" read: "The stabilizer
“Molniya” with a T-2S (T-2SA) sight and their installation in the tank did not provide the necessary
reliability and surety of action and should be improved upon with the elimination of all
malfunctions and shortcomings identified during the trials." Due to multiple cases of the appearance
of a muzzle flare and one case of a backflash during the tests of the 100-mm D-54TS cannon on one
tank, the dual baffle muzzle brake was replaced with a slotted brake. Slotted brake effectivity and
the pressure of the muzzle blast, it turned out to be more acceptable and was recommended for
installation on a gun instead of a dual baffle brake.
In general, the D-54TS met the specified TTRs in terms of ballistic, structural and operational
characteristics, showing that the lifespan of the barrel is within the threshold of 650-700 shots.
According to the commission, "the gun worked mostly normally", despite a slight expansion of the
barrel.
According to the results of the proving grounds-troops trials, the following conclusion followed:
"1. The T-54 tank with a new more powerful 100-mm D-54TS gun installed in it which
significantly increased its firepower while stabilizer two planes of gunlaying "Molniya" ensures
high efficiency of fire on the move and the fulfillment of the characteristics set by the government.
2. In the process of proving grounds-military tests of experimental samples of T-54 tanks with
D-54TS guns and a stabilizer “Molniya” alongside of shots for it, a large number of shortcomings
were revealed, some of which are of a fundamental nature, which is why the commission considers
it advisable to refrain from recommending trialed tanks for service until the shortcomings remarked
upon in the report are eliminated.
3. Taking into consideration the need to accelerate the arming of the T-54 medium tank with a more
powerful gun and more refined stabilization, in order to prepare and equip production in the
direction of its deployment in the future, recommend:
a) completion of experimental samples with the elimination of the specified deficiencies to be
carried out on three tanks that have undergone proving grounds-troops trials; check the quality of
elimination of deficiencies by control trials of these tanks and based on the results of these tests,
make a decision on the recommendation for armament;
b) simultaneously ensure the production of a series of T-54 tanks with D-54TS guns and “Molniya”
stabilizers in the amount of 15-20 units for accelerated military use(troops trials) in various climatic
conditions.
4. Considering that, according to the EDWs plan of 1957, work is being carried out on equipping
night vision devices to the T-54 tank with the D-54TS gun and the “Molniya” stabilizer , plant No.
183 should combine the fulfilment of this work with the implementation of measures (in accordance
to) this conclusion and equip one tank, out of two intended for control trils, with night vision
devices in accordance with with the existing contract.
Request the GAU, Plant No. 9 and the TsNII-173 in one of the gun and stabilizer kits being refined
to provide the possibility of autonomous communication of the “Luna” night sight with the gun and
disengagement of “adjustment” in stabilization mode when firing with this sight."

As it can be seen, despite the need for tanks with increased firepower to be received the troops, the
installation of a new artillery system with a “Molniya” stabilizer in the T-54A turned out to be not
entirely successful and, as it learned later wasn’t particularly expedient due to the limited volume of
the standard turret, despite changes in the design of its front and turret ring.
In addition to eliminating the remarks on the "Object 139", experimental devices "Uzor", "Luna-II"
and "Ugol" were tested on the serial T-54B, which were also intended for the "Object 140" and
"Object 430". The successful results of factory and state trials made it possible to introduce them
into mass production on the T-54B tank.
In the experimental workfloor for the T-54B, the placement of the experimental USPPO system, the
commander's radio station R-112 and other experimental units and mechanisms was worked on. At
the same time, SKB-183 was able to select a fire extinguishing compound "3,5" which was more
effective than carbon dioxide, consisting of 70% ethyl bromide and 30% carbon dioxide. This
composition was used in the systems of aircraft FSS*, and it was 2.3 times more effective than
carbon dioxide and did not have such a harmful effect on humans.
On May 25, 1957, SKB-183 received an instruction from NTK GBTU No. 3/492987 to install the
“Karmin-2” device on a medium tank following plans from plant No. 355.. It was designed as a
combined commander's day and night observation device operating in conditions of nightly natural
illumination. "Karmin-2" was considered very promising, because when using it there was no need
to install a vulnerable IR spotlight. This device did not reveal the tank at night, and in preparation
for night operations, it was not necessary to remove the day commander's device and replace it with
a night one.
However, the "Karmin-2" had significant dimensions (length – 1250 mm, diameter of the lower part
– 300 mm, head – 200 mm) and could not be installed in the serial T-54 without implementing
significant changes in a design of the turret.
In the same year, SKB-183 mounted in the T-54B another modification of the tank commander's
observation device – "Karmin-3" (these works were carried out by decree of the Council of
Ministers of the USSR No. 450-273 of April 11, 1956). In December 1957, the “Karmin-3” tank
was presented for state trials.
Experimental works on the introduction of a whole range of innovations on a serial tank allowed
plant No. 183 to bring the T-54B closer to the requirements of the GBTU for a new medium tank by
the middle of 1957, with the exception of such important points as increasing firepower and
reinforcing armor protection. At the same time, the tests of the first prototype "Object 140" revealed
significant shortcomings of the engine, transmission, cooling and air filtering systems.

To eliminate them, serious improvements and lengthy bench tests were required, which could
eventually lead to a radical change in the design of the tank. The least complaints were caused by
the fighting compartment of the "Object 140" with the D-54TS cannon.
Having studied the results of work on improving the T-54B, the chief of the Armored Forces,
Colonel-General P.P. Poluboyarov, on June 20, 1957, sent a tactical and technical task to plant No.
183 to develop a technical draft for a new medium tank, while at the same time it was required to
submit its draft for approval as soon as possible. It was necessary to produce in 1957 one sample of
a tank with a promising D-54TS cannon and all the innovations implemented in mass production.
In the TTT, the following points were specifically stipulated:
"1. Maximum preservation of interchangeability of parts and assemblies with the serial T-54B tank,
taking into account the installation in it: - an engine with a output of 580 hp;
- a planetary final drive;
- Roadwheel dynamic travel of 165 mm ;
- installation of underwater driving equipment;
- Engine exhaust thermal smoke system, instead of BDSh (smoke canisters);
- lightweight roadwheels with glue fastening of a rubber tire.
2. The hull of the tank in terms of the thickness of the side plates should be the same as that of the
T-54B tank.
3. It is desirable to borrow the turret of the tank with armament and the turret ring of the turret from
a new medium tank being developed by the plant ("Object 140").
4. Installation of gun stabilization in two planes, night sight ("Luna") and night vision devices for
the driver and tank commander (TVN-2 and "Uzor").
5. The ammo compliment for the gun must be at least 40 shots.
6. The fuel reserve is 950-1000 liters, of which at least 75% is under armor. "
A detailed discussion of this proposal was held in July 1957, when P.P. Poluboyarov visited plant
No. 183. The director of the plant, I.V. Okunev, instructed SKB-183 to conduct the necessary
research on a prospective medium tank with a D-54TS cannon, provided that the interchangeability
of its parts and assemblies with the serial T-54B is preserved as much as possible.
According to the specialists of the plant, the most complete combination of high armor protection
with the needed useful armored volume (with minimal weight and the possibility of placing a turret
with a large turret ring diameter) could be implemented in a hull with curved sides that had different
thickness depending on height. This ensured differential armor of the sides in accordance to the
height of the vehicle.
Such hull was chosen for the new vehicle. Its upper frontal plate provided protection from 100mm
blunt armor piercing projectiles with a muzzle velocity of 930 m/s at any range; the lower frontal
plate - from a similar type of projectile, but at a velocity of 865 m/s. Side plates in the 45°
arc/sector: the upper belt provided projectile resistance to a 100 mm blunt armor piercing projectile
with a muzzle velocity of 930 m/s at any distance; the lower belt - from a similar type of projectile
with velocity ranging from 825 to 930 m/s. This was significantly higher than protection afforded
by the hull plates of the serial T-54B.
It was proposed to borrow the tank's turret with turret ring, armament and all equipment from the
"Object 140", but without installing an anti–aircraft machine gun, and with the main engine bay
units from the T-54B tank. The distance between the sides of the hull was chosen to be 1800 mm
instead of 1850 mm on the T-54, so there was a need to reduce the length of the engine crankshaft
pulley end by 50 mm. The manufacture of such a modification of the engine was easily coordinated
with the ChKZ.
When designing the tank, the Nizhny Tagil’s designers managed to fully fulfill P.P Poluboyarov’s
tactical-technical task, and the ammunition complement of the gun was brought to 45 shots instead
of the recommended 40. The calculated weight of the tank was estimated to be about 600 kg higher
than that of the "Object 139" with the D-54TS cannon (of which 400 kg accounted for the laying of
an additional 11 shells and 200 kg – to increase the fuel capacity). Thus, the weight of the machine
did not exceed 37 tons, and the specific ground pressure due to the increase in the contact patch
surface was 0.75 kg / cm2 instead of 0.81 kg/ cm2 for the T-54B.
Plant No. 183 was obliged to produce one experimental sample in the third quarter of 1958. with
the use of an already made turret of one of the factory "Objects 140" alongside of the sides and a
under turret hull roof backup billets/blanks.
A detailed description of the proposed draft was presented by the director of plant No. 183 on
November 26, 1957 in a letter No. 2077 to P.P. Poluboyarov and the Minister of Defense Industry of
the USSR D.F. Ustinov. In particular, I.V. Okunev noted:
"I ask you to confirm your consent to the creation, along with the "Object 140", of a new medium
tank with the elaborated above characteristics in the volume, order ,and deadlines proposed by us.
At the same time, I ask you to approve an unclassified index for the new tank – "Object 142".

Simultaneously with the letter, a comparative table of the TTC* of serial and prospective medium
tanks was prepared. After reviewing all the materials submitted by SKB-183, the Ministry of
Defense appealed to the Council of Ministers of the USSR with a proposal to stop work on the tank
"Object 140". The Defense Technology Committee agreed with this proposal. Officially, this topic
at plant No. 183 was discontinued by Resolution of the Council of Ministers of the USSR No. 609-
294 dated June 6, 1958.
The immediate predecessors
In the second half of 1957 SKB-183’ Department 520 under the leadership of L.N. Kartsev
completed the project of a new medium tank "Object 142" with a 100-mm D-54TS gun. This
vehicle was in many ways a further development of the "Object 140" design. It had a classic layout
scheme with a crew of four: a commander, a gunner, a loader and a driver.
The driver’s compartment with an ingress hatch in the roof of the hull was located on the left side,
as on the experimental "Object 140". In driver station following is located: all the drives for
controlling the movement of the tank, a control panel (like T-54B driver station), a gyro semi-
compass GPK-48, compressed air cylinders for starting the engine and auxiliary armament (hull
SGMT) with part of the ammunition complement. Fuel tanks and batteries were installed in the
forward part of the hull right side. To drive the vehicle two periscope viewing devices were
mounted in the shafts at a upper edge of frontal plate (the right device relative to the left was
located at an angle of 15 °). Cleaning of observation devices from dust and dirt was carried out with
the help of rubber wiper (same type of devices as used in the T-54B). In addition, the left viewing
device was equipped with a hydro-pneumatic cleaning system. When driving the tank at night, the
driver mechanic used the TVN-2 night vision device, which was mounted instead of the left
viewing device. To illuminate the terrain, the FG-100 headlight with an infrared filter was used,
which was installed on the hull frontal plate, to the left of the FG-102 headlight with a blackout
cover. Behind the driver's seat in the bottom of the hull there was an emergency exit hatch with an
armored cap on hinges.
In the fighting compartment (located in the middle part of the hull and in the turret) there was a
main and auxiliary armament with ammunition, a fire control system, observation (day and night)
devices, crew stations, etc. It was similar to the fighting compartment of the tank "Object 140".
The engine bay was located behind the fighting compartment in the rear part of the hull and was
separated from it by an engine bay firewall. The layout of the engine bay repeated the layout of the
corresponding T-54B compartment.
The main armament of the "Object 142" was a 100-mm rifled tank gun D-54TS with a two-plane
stabilizer "Vyuga", equipped with a slotted muzzle brake and an ejection device for barrel
scavenging after firing. A 7.62 mm SGMT machine gun was paired with the cannon. The second
SGMT (hull one) was placed to the right of the driver. The anti-aircraft 14.5 mm machine gun
KPVT mount was eliminated. There was also no mechanism for ejecting spent cartridges after firing
from a gun, since its design had not yet been completed.
When firing from a gun and a coaxial machine gun, the gunner used a TSh2A telescopic sight
during the day, and a TPN-1 sight at night. The gunlaying angles of the coaxial armament mount
vertically ranged from -5 to +16 °.
The ammunition complement for the gun (50 rounds) and its placement in the tank remained the
same as in the "Object 140". Since the KPVT anti-aircraft machine gun with its ammunition was
abolished, the ammunition for the coaxial and hull SGMT machineguns was increased to 3,500
rounds.
In addition, two 7.62 mm AK-47 avtomats with ammunition, 12 F-1 hand grenades and a signal
pistol with 12 signal cartridges were placed in the combat compartment.
The armor protection of the tank is differentiatial and shell resistant. As already mentioned, in the
manufacture of the vehicle’s hull, a backup set of billets of the sides and a under turret hull roof for
the experimental tank "Object 140" was used. The upper and lower frontal plates of the hull had an
armor thickness of 100 mm and were angled at an angle from the vertical of 65 and 61 °,
respectively. The upper frontal sheet of the hull provided projectile resistance from a 100 mm blunt
armor piercing projectile with a muzzle velocity of 930 m/s at any distance; the lower frontal plate -
from a similar type of projectile, but with a lower muzzle velocity - 865 m/s.
The use of variable crosssection side armor in the hull design (80 mm in the lower part, 57 mm in
the upper part), followed by bending, made it possible to provide more reliable protection of the
upper part of the vehicle side. The side plates in the firing arc of ± 22.5° guaranteed to have same
protection as the frontal parts.
The cross–section of the hull at fighting compartment had the form of a "shot glass", while the front
and part of the hull occupied by the engine bay appears like/looks like hexagon. In the front this
was achieved thanks to the profile of the stamped roof of the control compartment, and in the rear
by a cut in the upper part of the sides and the addition of special “headscarf” shaped plates. The rear
of the hull was welded from two rolled armor plates 45 and 30 mm thick, placed at angles of
inclination from the vertical of 17 and 70 °, respectively.
The roof of the vehicle hull under the turret was similar to the all-stamped under turret part of the
Object 140 hull roof. Only the roof of the engine bay underwent changes due to the new design of
the rear part of the hull and the use of a fan driven engine cooling system .
Along with increasing the protection of the upper part the geometry of the hull allowed the use of a
increased diameter turret race ring and thus significantly improve the placement of assemblies and
crew in the turret. The clearance diameter of the turret race ring turret ring of the was 2250 mm.
Due to the “cuffs/lapels” of the sides, it was possible to package additional internal volumes into the
hull.
The louvres of the engine cooling system in the roof of the engine bay had a closing mechanism that
triggered automatically during a nuclear explosion, thereby reducing the impact of the shock wave
on the compartment assemblies.
The cast turret with a welded all-stamped roof and with a ball bearing race ring was borrowed from
the second prototype "Object 140". In the frontal part it had a variable armor thickness from 240 to
150 mm with inclination angles ranging from 0 to 55 °. The turret side maximum thickness was 220
mm. In regards of projectile resistance, the front of the turret was equal to the upper frontal plate of
the hull in the firing arc of +45 °.
In the rear part of the turret roof there was a hatch for ejecting spent propellant cases and an
armored hood of the exhaust fan. Above the loader's workplace, a special high cupoula was
retained, which was previously intended for the installation of an anti-aircraft machine gun pintle.
The tank was equipped with ANP*(NBC with emphasis on Nuclear), UA PPO and EETS(ESS)
systems, similar to the systems used in the "Object 140".
The main the power plant was diesel A-137-6-B (V-55) with a output of 426 kW (580 h.p). The
(engine) start was carried out by the ST-16M starter with a power of 11 kW (15 h.p.) either with
compressed air from two five-liter air bottles, which were charged using an AK-150 compressor, or
by a combined method. All the main components and assemblies of the power plant and its system
(except for internal and external fuel tanks, as well as the heater borrowed from the "Object 140")
were interchangeable with similar units and units of the T-54B. The capacity of internal (under
armor) fuel tanks was 715 liters, external – 285 liters. The travel range on the highway reached 500
km.
The transmission of the vehicle was similar to the transmission of the T-54B tank, except for the use
of combined final drives and an gearbox air compressor power take off drive . The design of the
drivetrain was also borrowed from the T-54B, but the arrangement of the roadwheels was changed
to ensure a more uniform distribution of the weight of the vehicle across the roadwheels due to the
use of a new hull and turret.
The electrical equipment scheme has not changed in comparison with the T-54B electrical
equipment scheme. For external communication, the R-113 radio station was installed on the tank,
and for internal communication, the R–120 tank intercom device was installed.
The tank could overcome water obstacles with the help of underwater driving equipment.
The experimental sample of the "Object 142", manufactured in the first half of 1958, passed factory
trials in the autumn of the same year. It is curious, but due to circumstances that have not yet been
clarified, this vehicle passed under the name "Object 165" (the first sample) in the NTK GBTU.
All work on the "Object 142" was stopped due to the transition of plant No. 183 to the production of
the T-55 tank and the deployment of the EDW to improve its combat qualities.