T-54 Model 1949
The poor showing of the T-54 led to a heavy redesign. The turret was completely changed with the wide mantlet being replaced by a narrow gun mantlet. The new turret also avoided the shot-traps at the front corners by adopting a hemispherical shape. An improved antiaircraft heavy machine gun ring mounting with the 12.7mm DShK was added to the turret roof. The fender mounted machine guns were removed as being impractical, and a single SGMT 7.62mm machine gun was added near the driver; it would fire through a hole in the glacis plate. These initial production vehicles introduced a multistage centrifugal oil-bath air filter for the engine, and an oil-supply preheater for cold weather starting. A new track was introduced which was widened 80 millimeters to a total of 580 millimeters for better flotation on poor ground.
This version was designated the T-54 Model 1949 and went into full-scale production in 1950 at the three main tank plants at Nizhni Tagil, Omsk and Kharkov. This was the first version of the T-54 built in significant numbers. The initial T-54 Model 1946 tanks were later rebuilt to at least this standard.
T-54 Model 1951
The T-54 underwent continual modernization through the early 1950s. In 1951, the turret casting was changed, probably to simplify manufacture. The overhang at the rear of the turret was completely removed, giving the T-54 Model 1951 its classic hemispherical shape, resembling half an egg shell. This version also replaced the previous TSh-20 gunner's sight with the TSh-2-22. Turret bearings were improved for greater durability, and the vehicle electronics were better sealed from dust. This version also was the first to regularly introduce mounting attachments for mine-rollers (initially the PT-3, and later the PT-54).
T-54A Model 1951
The Soviet Union received some experience with gun stabilzers on the M4A2 Sherman tanks provided under Lend-Lease. The first Soviet tank to introduce a gun stabilization system was the T-54A. The T-54 had a probability-of-hit of only 3 percent while the tank was moving; the objective was to increase this to 30 percent by adding a one-axis stabilizer. Two bureaus competed on the project, V.G. Grabin's design bureau, and a small design team under I.V. Pogozhev. As the T-54 was armed with the 100mm gun from his arch rival Petrov, Grabin offered a new 100mm gun with a new stabilization system.
Pogozhev adapted his system to the existing D-10T gun, which won state approval since it would prove to be a less costly solution. The modified gun with the new Gorizont (Horizon) vertical-plane gun stabilization system was designated D-10TG and was incorporated into the new T-54A tank. The D-10TG 100mm gun was modified with a new fume extractor at this point. The fume extractor was another probable American influence, as in the autumn of 1950, the North Korean Army and Chinese Volunteer Army had captured several M46 tanks during the retreat from Pyongyang. Other internal improvements included a new multistage air cleaner and radiator vane controls for improved engine performance.
The Red Army had been experimenting with deep fording tanks since the late 1930s as a means to hastily cross rivers. Work continued in the early 1950s, with experiments on T-34-85s and other tanks. The T-54A was selected as the first tank to be regularly fitted with this equipment, as the hull configuration made it easier for sealing than the T-34-85. This was the first version of the T-54 series regularly fitted with the OPVT [Oborudovanie dlya podvodnogo vozhdeniya lankov, equipment for underwater tank driving river fording equipment].
The OPVT system consisted of vehicle sealing equipment and a snorkel tube system. Although part of the sealing system was permanently fitted to the vehicle in the factory, attaching the snorkel and adding the additional sealing took about 1.2 hours to complete. The OPVT system allowed a tank to ford rivers to a maximum depth of 5 meters, a maximum width of 700 meters and a maximum river flow speed of 1.5 meters per second. The tank can fire its main gun about 30 seconds after having left the river, but it takes 10 to 15 minutes to completely remove the sealing equipment from the tank. The tank is steered underwater using the GPK-48 gyrocompass.
During underwater fording, the crew usually wears a special escape breathing apparatus. In the event that the tank is stranded mid-stream, the tank interior is gradually flooded, and once filled, the hatches are opened, and the crew escapes. Deep wading is a very dangerous process since river bottoms are irregular, and the tank has a certain measure of buoyancy which degrades traction and steering. Deep wading operations are usually prepared by special river reconnaisance teams, and often a tank recovery vehicle is the first vehicle sent across in order to help tow out stranded tanks. Nevertheless, this feature allows Soviet tank units to cross river obstacles, unaided by engineer bridging equipment.
The OPVT system was retrofitted to many older tanks, including the T-34-85, and thereafter was included as a standard feature of Soviet tanks beginning with the T-54A. For training purposes, a second tube was developed which was wide enough to permit the tank crew to evacuate the vehicle if it became bogged down on the river bed.
The T-54A was also the first Soviet tank fitted with a driver's night vision system. This consisted of an infrared headlight and a metascope periscope that could be substituted for the normal daylight periscope.
Limited production of the T-54A began in the USSR in the autumn of 1954. The stabilizer proved troublesome, and production improvements were continually added over an 18-month period, finally resolving the difficulties. Shortly after series production began, a new style of road-wheel was introduced with a distinctive starfish pattern. This subsequently became the standard style on the T-54A and the subsequent T-55 and T-62 as well. The original spoked wheel became uncommon, as the new wheel was added to older T-44s and T-54s during their periodic rebuilding.
T-54B Model 1952
The first Soviet experience with tank night fighting occurred in Hungary in January to February 1945 when the 1st Guards Mechanized Corps, equipped mostly with Lend Lease M4A2 Sherman tank, was engaged on several occasions by German Panther tanks equipped with an early active infrared night fighting system. The German system consisted of an infrared searchlight mounted on a supporting armored half-track vehicle; the Panther tanks carried a metascope for viewing the infrared illumination. The Soviets captured samples of this equipment later in 1945. It is not known if they experimentally deployed the German system, but they waited for a more practical autonomous system before making a major investment in night fighting equipment.
Some T-54As were fitted with an active infrared night driving system consisting of an FG-100 infrared headlight and a TVN-2 driver's night periscope. The first Soviet tank regularly equipped with night fighting equipment was the T-54B Model 1952, with the prototypes completed at Nizhni Tagil in 1952. This version introduced a Luna L-2 infrared searchlight on the turret front, an OU-3 IR searchlight on the commander's cupola, and a TPN-1 gunner's day/night sight in place of the simpler MK-4 periscope in front of the gunner's station which included a night channel with metascope.
The T-54B also introduced the Tsiklon (Cyclone) 2-axis stabilization system as part of the improved D-10T2S 100mm gun. The previous Gorizont stabilization system was only in one-axis. The new stabilization system, based around the STP-2, was of a fairly elementary nature and did not offer real fire-on-the-move capability. Rather, it kept the main gun pointing with a rough accuracy so that once the tank halted for firing, only minor aiming adjustments would be needed. The T-54B was also fitted with an electric power traverse to supplement the normal manual turret traverse. It enabled the turret to be completely rotated in under 30 seconds.
The Polish equivalent of the T-54B was designated T-54AM, a designation which sometimes erroneously is used in the West for this type whether Soviet or Polish.
Series production of the T-54B version began in the USSR in early 1957.
T-54M
Developed under the code name Obiekt 140 towards the end of 1953, the T-54M was a major modernization of the T-54, with a new, long barreled D-54 100mm smoothbore gun designed by A.A. Barikhin at the Petrov design bureau in Sverdlovsk. The new gun had superior armor penetration to the D-10T and the tank could carry 50 rounds of ammunition instead of the usual 34. This vehicle was supposed to carry the 14.5mm KPVT machine gun in lieu of the usual DShK, but what few photos exist of it show the normal antiaircraft machine-gun mount. The engine was an improved V-54-6. This vehicle never entered quantity production, and at a later date, the designation T-54M was applied to modernized T-54 with the D-10T2S gun found on the T-54B. The D-54 gun served as the basis for the later 115mm U-5T on the T-62 tank.
T-54K Model 1954 - Command Tank
This was the first standard command version of the T-54A, built in small numbers. The additional R-112 command radio was incorporated into the turret by reducing the ammunition storage. The only external indication of its command function was the addition of an antenna stowage tube on the hull rear. Nearly all subsequent Soviet tank types had command derivatives which had an additional radio along with necessary antenna stowage.
The T-54AD was the Polish command version equivalent of the T-54K, the "D" indicating dowodca, or "commander." This version has a modified turret with a slight extension on the turret rear to provide space for the command radios. This vehicle is used by regimental commanders and regimental chiefs-of-staff. A similar Polish T-55 derivative was also built.
OT-54 Flamethrower Tank
This tank for engineer troops substituted an ATO-1 automatic flamethrower for the usual co-axial machine gun. The original prototype, the Obiekt 483, had the flamethrower replacing the 100mm gun. This approach was not favored, however, since it was quite obvious that the tank was a flamethrower; this could lead to special attention from enemy forces. Instead the vehicle was redesigned to be armed with both the 100mm gun and flamethrower. The bow ammunition stowage was modified to permit carrying 460 liters of flammable liquid using compressed gas for propulsion. Maximum range was 160 meters, and the system could fire 15 to 20 bursts per minute.
T-54 Rebuilt Tanks
A confusing aspect of identifying T-54 tanks by their sub-type was the regular Soviet practice of periodically rebuilding older tanks to newer standards. The Soviet Union established several rebuilding plants (remzavod: remontniy zavod, rebuilding plant) specifically for this purpose, the largest being in Kiev. The criteria for rebuilding varied through time: every 7,000 kilometers, every 500 engine operating hours, every 10 years, or due to a special modernization program.
As older versions of the T-54 tank were gradually returned for their periodic rebuilding, some of the new features of the T-54A and T-54B were added including the new wheels, infrared night-fighting equipment, OPVT deep fording fittings, and other features. It is very difficult to identify the various versions of the T-54 on the basis of external appearence. For example, a T-54 Model 1951, rebuilt with a new D10-T2S gun, new gunner's sight, IR equipment and new wheels, is virtually indistinguishable from a T-54B. NATO sometimes designates these vehicles as T-54(M) and T-54A(M); the Soviet Union generally designated the tank on the basis of its rebuilding standard, so that a rebuilt T-54 Model 1949 was considered a T-54B if all the new features were incorporated.
