The Stridsvagn 103 (Strv 103), also known as the S-Tank, is a Swedish post-World War II main battle tank, designed and manufactured in Sweden. Developed in the 1950s, it was the first main battle tank to use a turbine engine and the only mass-produced tank since World War II to dispense with a turret. It has an unconventional design with a unique gun laying process: it is turretless with a fixed gun traversed by engaging the tracks (like the 75mm gun on the 1930s French Char B1) and elevated by adjusting the hull suspension. The result was a very low-profile design with an emphasis on survivability and heightened crew protection level. Strv 103s formed a major portion of the Swedish armoured forces from the 1960s to the 1990s, when, along with the Centurions, it was replaced by the Leopard 2 variants Stridsvagn 121 and Stridsvagn 122. While most turretless armoured fighting vehicles are classified as assault guns or tank destroyers, the Strv 103 is considered a tank since its designated combat role matched those of other tanks within contemporary Swedish doctrine.
Stridsvagn 103B: As the weight of the Strv 103 had increased compared to the pre-production tanks, the 103 turned out to be under-powered. Hence, a more powerful version of the same gas turbine, manufactured by Caterpillar, was introduced after the first production run of 80 tanks. The early version tanks (retroactively designated Strv 103A) were soon upgraded to B-standard. Adjustments to the hydro-pneumatic suspension increased elevation range from −10 through +12 degrees, to −11 through +16 degrees.
