The T-54 was the result of adding the D-10 100mm gun to the T-44 hull to produce a new medium tank capable of holding itís own on the battlefield. In order to accommodate the D-10T 100mm gun, it was necessary to design a new turret and carry out extensive modifications to the hull of the T-44. By adding armoured fillets at the mid-section of the T-44 hull, it was possible to expand the turret ring diameter sufficiently to accommodate the larger weapon. When the new turret and gun assembly were fitted to a modified T-44M hull, the resulting vehicle was designated T-54. The T-54 entered active service in 1949 and at the time was the most advanced tank of its class in the world.
The first model T-54 shared the same wide mantlet as the preceding T-44, and the numerous overhangs and shot-traps resulted in the turret shape being far from ideal. Consequently, an improved type soon followed the initial production model. This second model featured a new 'pig snout' mantlet, but it still had a turret overhang at the rear. It was not until the third model was introduced in the mid-1950s that the now familiar, standard T-54 emerged. The third model retained the 'pig snout' mantlet, but dispensed with the turret overhang. This new turret resembled a horseshoe crab shell and consisted of three major pieces: the turret casting proper, and two flat roof panels out of which sprouted the loader's and tank commander's hatches.
The T-54 is a straightforward, conventional design, noteworthy for its small size in comparison to comparable Western European or American designs. It has a four-man crew, consisting of a driver, gunner, gun loader and commander. It has good speed and manoeuvrability, though its loose 'dead' track is more apt to shed during violent turns than the track types used on Western tanks. Its 100mm gun is comparable to the 90mm gun used on the American M-48 Patton.
The hull is of a conventional welded construction with a simple box-like cross-section and boat-hull flanged edges where the suspension arms meet the hull. The transmission and engine are located at the rear of the hull and, unlike conventional designs, the engine is mounted transversely against the axis of travel. Engine fuel is stored internally in two cells; one beside the driver around the ammunition under the right side of the glacis plate, and another just before the engine. This internal fuel capacity of 115 gallons (522 litres) is supplemented by three external fuel panniers of 21 gallons (95 litres) each. Depending upon the production batch, T-54s can also be fitted with either one or two additional 44-gallon drums (200 litres) at the rear of the hull, bringing the total to approximately 264 gallons (1,200 litres). Beneath the large fuel drums, or to the side, the older models could carry two BDSH smoke dispensers, but retrofitted models carry a thermal smoke discharge system.
The driver steers the vehicle using a conventional clutch and brake system. Foreign engineers who have test driven the T-54 have commented on the strength required to drive it. This is due to the absence of pneumatic or hydraulic boosting on the controls although newer Polish- and Czechoslovak-produced machines did have this feature. To the right of the driver is a fuel cell and one of the main ammunition racks for the gun. A semi-fixed SGMT 7.62mm machine-gun is fitted in the centre of the glacis plate and is controlled by the driver. Many tanks have had this gun removed and the firing point blanked over due to the dubious utility of such a weapon. The driver is provided with two periscopes for viewing when the tank is buttoned up, and the seat is easily adjustable to raise the driver's head outside the hatch when not in combat zones. A hood and windscreen are carried for use by the driver in bad weather.
The turret arrangement of the T-54 is unconventional in several respects. As on the T-34-85 and T-44, the gunner and commander occupy the left half of the turret, and the loader occupies the right, the reverse to Western practice. The turret is not fitted with a basket, but the crew is suspended above the hull floor on seats. The turret is so cramped that the gunner nearly sits in the commander's lap. The bulky D-10T gun takes up a large portion of the turret's internal space and further congestion is caused by a ready-rack for ammunition stowage along the rear wall.
The fire controls for the armament are considerably simpler than those used on comparable foreign types. While the United States favoured an optical coincidence or stereoscopic rangefinder, the Soviet Army stuck to a simple stadiametric system. To engage a target, the tank commander locates a target using his TPK-1 designator sight and swings the turret roughly in line. Using the ranging graticule on his sight, the commander estimates range, informs the gunner of the type of ammunition to be used and the range of the target. The gunner takes over, fine aims the D-10T with his TSh-22 articulated telescope and fires. Should another shot be needed, the gun must be fully elevated to give the loader room to extract the spent casing and reload, and the gun must be resighted. The main drawback to this layout, apart from the time-consuming reloading procedure, is the relative inaccuracy of a stadiametric system compared to other methods, particularly at longer ranges. At close ranges, the system does allow for quick reaction time.
As production continued, the D-10T was refined. In 1955, a new version of the basic T-54 appeared which, in the West, is usually designated T-54A. It was fitted with the newer D-10TG gun, which was gyro-stabilized along the vertical axis and had power elevation. It can be easily distinguished from preceding models by the small counterweight fitted at the fore end of the main gun to compensate for the stabilizer. Later, a bore evacuator was fitted. Internally, the vehicle had new air filters, an electric oil pump, a bilge pump for wading and snorkelling, an automatic fire extinguisher layout, and it was eventually fitted with additional external fuel cells.
About two years later, additional refinements led to the very similar T-54B. Once again, the major changes were internal. A new model of the 100mm main armament was fitted, the D-10T2S, which had stabilization in both planes, derived from similar units on US Lend-Lease equipment. For the first time, infrared night vision equipment was provided for the tank commander and gunner as a standard production feature. Other features included improved snorkel gear. The final major production type was given the US Army designation T-54X to signify its transitional role between the T-54 and T-55 family. The T-54X was essentially the same as the T-54B, but dispensed with the turret 12.7mm Degtaryev anti-aircraft machine-gun and cupola and featured a simple flush loader's hatch instead.
The T-54X was followed shortly afterwards by the T-55, which was first shown publicly at a parade in Moscow on 7 November 1961. This tank did not differ from the preceding T-54 series in any major respect, but basically represented a culmination in the technical improvements begun in the early 1950s. The major refinements in the T-55 were the uprated V-55 engine, an improved transmission and a rotating turret floor. The only external difference between a T-54X and a T-55 is the T-55's lack of the large circular roof vent forward of the loader's hatch. This vent is the key feature in distinguishing T-54s from T-55s.
With the introduction of the T-55, many of the earlier T-54s were re-manufactured or refitted with the new modifications, particularly the L-2G infrared searchlight and complementary vision devices. Some were also fitted with two-plane stabilization. Most notable among these retrofits were the T-54(M) and T-54A(M).
At the 1963 May Day Parade, the final major mutation of the T-55 family, the T-55A, was first seen. The T-55A differed from the preceding model in having raised covers and anti-radiation lining over the two turret hatches and over the driver's position. The T-55A dispensed with the hull machine-gun, though many later production T-55s also had this modification and many other earlier types had it removed during repair. The space taken up by the machine-gun and its ammunition allowed the T-55A to carry six more rounds of 100mm ammunition. Although the standard production models of both the T-55 and T-55A were not fitted with the Degtaryev 12.7mm anti-aircraft machine-gun, many have subsequently been retrofitted with this feature, and are designated T-55(M) and T-55A(M), respectively. This was done largely in reaction to increased Western interest in tactical strike aircraft and assault helicopters.
The People's Republic of China produces an unlicensed copy of the T-54, designated T-59, which is essentially similar to the basic T-54 but with some simplifications. China also produces two AFVs in the light tank category that strongly resemble the T-54. The first of these, the T-62 light tank (not to be confused with the Soviet T-62 medium tank), is essentially a T-54 with thinner armour, fitted with a 85mm gun and narrower tracks. The T-63 is a peculiar 4/5 scale mimic of the T-54, using the turret from the T-60 light amphibious tank with an 85mm gun, and the running gear of the K-63 armoured troop carrier.
The T-54/55 family has been used as the basis for a number of self-propelled guns, tractors, bridging vehicles and armoured recovery vehicles. It has been built in larger quantities than any other post-war tank and has probably even exceeded the prodigious output of its predecessor, the T-34, which totalled at least 60,000 vehicles, not counting self-propelled gun and special purpose variants. As such, it is the most widely produced tank in history. In comparison, the total output of the post-war American tank family of the M-26, M-46, M-47, M-48 and M-60 amounted to only about 28,000 vehicles. Some estimates of the T-54/55's sixteen-year production run places the final total at well over 100,000 vehicles.