Switzerland following the Second World War wanted to preserve its neutrality. Having seen the Soviet tank armies roll over Nazi Germany in 1945 and the impressive IS-series of heavy tanks, and the Western counters such as the FV214 Conqueror and the M-103, it was clear that a heavy tank would be needed with sufficient firepower and armour to destroy similar tanks. Design work began in 1948 but it wasn't until 1950 that the innovative oscillating turret was included. This allowed good elevation and more importantly good gun depression allowing the tank to make full use of hull-down firing positions. The gun was developed from British 120mm designs and was fitted with a bespoke Swiss-developed 8-round autoloader which could be refilled from secondary stowage within the hull - therefore a loader was still required. The highly shaped turret offered superb armour protection and at its inception this was thought to be one of the most advanced tanks in the world. A modified Y-3 aircraft engine was also fitted. A prototype chassis was first run in 1952 but it wasn't until 1955 that six prototypes were completed and following extensive trials the first of just 90 tanks were introduced into service in 1958. Never exported, the Pz.57 was upgraded with passive IR and a laser rangefinder in the late 1970s and remained in service until 1994.
Weight: 48 tonnes
Length: 7.42m (hull), 11.99m (inc. gun)
Width: 3.66m (inc. skirts)
Height: 3.03m (commander's cupola)
Crew: 4 (commander, gunner, loader, driver)
Armour: hull front 120 mm at 60° angle; lower glacis 100 mm at 30° angle; hull side: 90–130 mm at 9-25°; turret front 120 mm (at 60° angle), turret side 135 mm at 5° angle (bustle only 50mm).
Main Armament: 1x 120mm rifled gun with 8 rounds in an autoloader carousel and 30 rounds stored in the hull
Secondary Armament: 1x 7.5mm coaxial machine gun (2,000 rounds), 1x 7.5mm anti-aircraft machine gun (1,8200 rounds)
Powerplant: 800hp Saurer YS-3 12-cylinder V-12 liquid cooled petrol engine
Transmission: 7-gear manual gearbox
Suspension: torsion bar spring mounted support roller drive with hydraulic dampers
Ground clearance: 45cm (normal)
Operational Range: 240km
Speed: 40km/h (road), 27km/h (cross-country)