The T-55A is a variant of the extremely-popular T-55 main battle tank produced by the USSR after the Second World War. Along with the earlier T-54 main battle tanks, the T-54/T-55 MBT family is the most-produced tank series in history. The T-55 MBT design featured numerous improvements over the prior T-54s, including additional NBC (Nuclear, Biological & Chemical) protection systems, a new heavier turret, more ammunition, and improved equipment. The T-55A was a late modification of the earlier T-55 MBT, including improved NBC systems. The T-54/T-55 family of main battle tanks were among the first main battle tanks to be introduced. The tanks were designed as a follow-up to the T-34 and T-44 medium tanks. Notably, the new T-54/T-55 tanks were fitted with a 100 mm rifled gun that was capable of penetrating the most heavily-armoured western tanks of the time but had a faster reload compared to the 122 mm guns used on the IS-series of heavy tanks. The T-55 was designed as an evolutionary development of the T-54 MBT and included numerous changes compared to the previous tank model. Notably, the T-55 received NBC protection equipment designed to protect against tactical nuclear weapons. The T-55A further improved on the T-55's NBC protection system by introducing a full chemical weapon filtration system along with an anti-radiation lining inside the tank. These improvements greatly increased the crew's survivability against nuclear or chemical warfare. Compared to the T-54, the T-55 had its total shell capacity increased from 34 to 45; the T-55A was able to carry six more shells, through the removal of the hull machine gun. The T-55A began production in 1963 and continued until 1977; numerous improvements were developed, including the T-55AM, a modified version of the T-55A featuring composite armour. The T-55 family served extensively with countries of the Warsaw Pact and was exported to many other countries. The T-55 family was retired from the Russian army in 2012 with remaining vehicles sold off to other countries; variants of the tank remain in service with numerous countries.
-WT Wiki