by D. N. Bolotin
Tank machine guns are a modification of light or mounted
machine guns with consideration of their placement in the combat vehicle. Due
to the difference in operating conditions of tank machine guns they have a
number of design peculiarities in comparison with field models. The limitation
of space of the crew of tanks makes it necessary to introduce a number of
devices which make their operation easier, to prevent excessive contamination
of the combat crew with gas, provide remote control of fire and remote loading
and reloading of the weapon, collection of spent shells avoiding wedging in the
mechanisms in the combat compartment, and attachment of the machine gun using
minimum area. The necessity to lay intensive fire in the worst conditions of
barrel cooling, the impossibility of changing them, all requires using more massive
barrels or special devices in tank models for cooling them during firing. The
limitations of space in the combat section of tanks mainly determines the
caliber of the small arms and the size of the ammunition fire unit and makes it
necessary to use devices which regulate the rate of firing and length of rounds
for more effective destruction of targets with minimum expenditure of
ammunition.
Depending on the caliber, tank machine guns are intended for
destroying personnel or repelling aviation attacks by the enemy and to combat
any target with light armor.
The first model of the Soviet tank machine gun was created
on the base of an infantry machine gun of the 1927 model Degtyarëv system and
recommended itself well at that time with the changes for an aviation model
design. This work was carried out in the first half of 1928 under the direction
of V. A. Degtyarëv with metal worker G. S. Shpagin who was later on to become
an outstanding designer.
On 17 August 1928 the Rifle Board reported to the Artillery
Administration of RKKA on the preparedness of the tank machine gun and
requested its more rapid consideration. If the report was not sent before 1
October, the Board could not guarantee fulfillment of the order for machine
guns.
In 1929, the Degtyarëv system 7.62-mm tank machine gun was
adopted as armament of the Red Army under the designation DT (Degtyarëv tank).
Its basic difference from the infantry model is the presence of an extensible
metal butt plate which made it possible in time of combat to decrease or
increase its length for convenience in laying fire and also after firing to
decrease its dimensions for more convenience for the person firing it when
moving. The machine gun is attached to the tank by a ball-and-socket unit which
consists of a socket attached to the armor of the tank and a ball attached to
the machine gun itself. Thus the design of the unit provides convenient turning
of the machine gun in vertical and horizontal planes, rapid aiming at the
target and firing in any chosen position. Its massive section reliably protects
the person firing it from bullets and shell fragments.
The magazine in the tank machine gun does not have a strap
with latch on top for rapid replacement of it because of the difficulty of
using them in a tank.
Differing from the infantry and aircraft machine guns, in
the tank model a dioptric sight is mounted which is regulated in horizontal and
vertical planes and depending on the firing distance can be set at 400, 600,
800, and 1,000 meters. The front sight is mounted in the port of the
ball-and-socket unit.
The DT machine gun successfully solved the specific
requirement for tank armament and thanks to its positive quality—simplicity of
design, reliability of action, unification with infantry and aircraft
models—occupied a firm position in the armament of tank troops. The DT tank
machine gun adopted as armament completed the creation of a complex of machine
guns for infantry, aircraft and tanks from a single automatic while retaining
the main parts of the basic model.
Combat use of DT machine guns during the Great Patriotic War
revealed certain design flaws in the system. A particularly important defect
was the position of the recoil-firing spring directly under the barrel. As a
result of this the recoil-firing spring during firing was heated because of the
high temperature of the barrel and shrank, lost the force of its compression
ratio and failed to work. In order to eliminate these defects, a modernized DT
machine gun was introduced in 1944. The recoil-firing spring was moved from
under the barrel to the trigger frame which eliminated the harmful effect of
the hot barrel.
The design for attaching the control tube of the piston was
changed which permitted stripping the machine gun without removing it from the
ball-and-socket unit of the tank and without leaving the tank.
The rods of the extensible butt plate, the shoulder rest and
the latch were made by stamping to cut down on their processing time.
After 1 January 1945 production of the DT machine guns was
stopped and industry converted to manufacture a more improved modernized model
which received the designation DTM (Degtyarëv tankovyy modernizirovannyy –
Degtyarëv tank modernized).
After the end of the Great Patriotic War, the Soviet
government in connection with the successful use at the Fronts in combat
activity of the 1943 model Goryunov system 7.62-mm mounted machine gun and
further improvements in its quality as a result of modernization, adopted a
resolution on accepting it as armament for armored troops as a target and
coaxial machine gun for installation on armored carriers.
The coaxial long-barrel 7.62-mm machine gun, SGMT (stankovyy
Goryunova modernizirovannyy tankoviy – modernized Goryunov mounted tank machine
gun) was mounted on medium tanks on a cantilever cradle. Laying it at the
target using a scale applied on the [word
illegible in the original] of the optical sight. The peculiarities of the
device of this machine gun are presented below.
Attachment of the machine gun is
accomplished on a cantilever cradle at two points. The forward attachment is
damped. The shock absorber is a spring with two-sided effect. The rear
attachment is supported.
There is no sight device on the
machine gun.
The trigger mechanism for remote
fire control is equipped with an electrical release.
The machine gun is equipped with a
box carrier for reliability of action of the automatics and the shell catcher.
The panel of the shell-discharge
port on the receiver is absent, that is, it is covered by the neck of the shell
catcher.
The ends of the belt have been
shortened for convenience in loading the machine gun.
The machine gun is fitted with a
special panel for protecting the crew from the lead bullet spray.
The coaxial SGMT machine gun is mounted in the driving
compartment and it is fired by the tank driver.
The machine gun is equipped with special boxes with belt
feeder and has a device for resetting the movable parts of the automatics.
Instead of a flash absorber, on the muzzle part of the barrel a lengthener is
screwed in for discharge of powder gases following the bullet beyond the
driver’s compartment. Laying the machine gun is accomplished by the tank crew
and therefore, he does not have sight devices.
The SGMB (stankovyy Gorunova modernizirovannyy
bronetrans-porternyy – modernized Goryunov armored carrier) machine gun is
mounted on armored carriers and differs from the SGM in that it is attached
not-to a mount but to a special unit.
Due to the unification of small arms on the base of the
Kalashnikov avtomat, the Goryunov system tank machine gun has begun to be
replaced by the PKT (Pulemyet Kalashnikova tankovyy – Kalashnikov tank machine
gun) Kalashnikov system which has the following peculiarities in arrangement of
its mechanisms and parts:
Due to the fact that it replaces
the Goryunov tank machine gun as armament it was necessary to retain the same
ballistic characteristics so that the optical sights would not have to be
replaced where the scale for the machine gun is marked according to the
ballistics of the SGMT. Therefore, the barrel length of the new model was made
722 mm, that is, the same as the SGMT and the initial velocity of a bullet with
steel center is 865 meters per second.
The barrel, in comparison with the
PK barrel, is made more massive by 1.2 kilograms for providing more intensive
fire.
For decreasing jumping of the
barrel in the receiver and retaining the same close pattern of firing as the
SGMT, the contact surface of the cylindrical part of the barrel with the
cylindrical part of the bore and the receiver was increased and a leaf spring
was introduced in the control rod of the piston so that in the process of
operation an increase in gap in the joints of the barrel and pipe with the
receiver would affect the close pattern of firing less.
For decreasing contamination with
gas of the combat compartment, a gas regulator is made on the principle of a
gas-bleeding section.
The sight devices are removed from
the machine gun, that is, sighting is done using the optical sight of a gun.
The butt plate of the machine gun
is removed.
Attaching the receiver to the
cantilever cradle is done like the attachment of the SGMT machine gun involving
a change in the design of the front and rear bushing of the receiver. The
forward attachment of the machine gun has a shock absorber.
For remote fire control in the
machine gun, an electrical release was introduced attached to the back plate of
the receiver instead of the butt plate.
Along with the 7.62-mm machine guns in the armament system
of armored troops, large caliber machine guns are widely used. The DShKT
(Degtyarëv-Shpagin krupnokalibernyy tankovyy – Degtyarëv-Shpagin large-caliber
tank) 12.7-mm machine gun has proven itself for anti-aircraft defense; it is
attached to the turret of the tank by a special unit.
The Vladimirov system 14.5-mm machine gun (KPVT
[krup-nokalibernyy pulemyet i Vladimirova, tankovyy – large-caliber Vladimirov
machine gun, tank]) is a powerful destructive weapon for enemy personnel and
anti-tank equipment; it is course with gun, mounted on heavy tanks.
In comparison with the KPV the tank variant has the
following design peculiarities:
For remote fire control the
machine gun is equipped with an electric release acting on a storage battery and
has a pulse counter of shots.
For convenience in loading and
reloading the machine gun there is a pneumatic loading mechanism which acts
from a compressed air cylinder.
For decreasing gas contamination
of the crew compartment the machine gun has a shell discharger.
For increasing the rigidity of the
housing and the possibility of changing the barrel without unscrewing the
piston, the housing diameter has been increased.
There are no sight devices, its
laying is accomplished using an optical sight.
Artillery armament plays the basic role in the
armament system of armored troops. Nevertheless, taking into account the
multiple conditions of carrying out combat operations under modern conditions,
one must not underestimate the role of small arms which most of all are an
effective means of combating light-armored targets of the enemy and its
personnel.
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| Complete mounting of DT tank machine gun. |
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| Complete mounting of DT tank machine gun |
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| DT tank machine gun. |
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| DT 7.62mm Tank Machine Gun. |
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| DT 7.62mm Tank Machine Gun. |
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| DT 7.62mm Tank Machine Gun. |
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| DTM 7.62mm Tank Machine Gun. |
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| DTM 7.62mm Tank Machine Gun. |
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| Machine gun turret of the STZ-5 armored tractor “Tank NI”. Odessa, Ukraine. August 1941. |
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| Factory workers and military officers next to the STZ-5 armored tractor “Tank NI”. Odessa, Ukraine. August 1941. |
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| T-26 light tank co-axial DT machine gun (Ps 164-32?, possibly OT-133 flame tank later fitted with gun turret) during the Finnish military Flag Day 2014 in Lappeenranta Rakuunamäki. |
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| DT-29 7.62 mm hull machine gun in T-34-85. |
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| IS-3 hull machine gun. |
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| DT/DTM hull machine gun in T-34. |
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| DP (top) and DT (bottom). |
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| 7.62mm DT 1929, used in the IS-2 as the hull machine gun as well as the coaxial machine gun. |
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| Japanese soldiers with captured DT machine gun at Battle of Khalkhin Gol, 1939. |
