an average of 1.7 hits were deemed necessary. The vehicle carries 300 rounds, and the ammunition is stowed as follows: 176 rounds in clips inside the turret, 72 rounds in clips in the hull front, and 52 separate (unclipped) rounds in special compartments under the turret floor. Armour-piercing rounds in clips are placed in the rear part of the turret to the left and right of the guns. Empty shell cases and clips are removed via a conveyor belt through a special port in the turret rear into an external metal wire basket on the back of the turret. Armour protection The ZSU-57-2's armour is welded rolled steel sufficient to protect the vehicle from 7.62mm armour-piercing bullets at 250 meters. Armour thickness is as follows: Hull front: (upper) – 13.5 mm; (lower) – 15 mm; at 60 degrees upper Hull sides: (upper) – 15 mm; (lower) – 13.5 mm Hull rear: 8 – 10.6 mm at 45 degrees Hull roof: 15 mm Hull bottom: 13.5 mm Turret sides: 13.5 mm Gun mantlet: 15 mm Turret roof: open Maneuverability The ZSU-57-2 has a maximum road speed of 50 kilometres per hour, which is reduced to around 30 km/h off-road. The vehicle has better acceleration compared with the T-54 because of its better power-to-weight ratio (18.6 hp per tonne). It has an operational range of 420 km on roads and 320 km across country. The vehicle can cross 0.8 m high vertical obstacles, 2.7 m wide trenches, ford 1.4 m deep water obstacles and climb 30° gradients. The ZSU-57-2 uses the same engine as the T-54. It is a water-cooled V-54 4-stroke diesel V12 engine with a displacement of 38.88 litres, which develops 520 hp (388 kW) at 2,000 rpm. The engine itself weighs 895 kg. Fuel capacity is 830 litres carried in three fuel tanks inside the hull (640 L total) and two external fuel tanks on the right fender each of 95 L; fuel capacity was increased in comparison with the T-54. External rear-mounted supplemental fuel tanks can increase the road range to 595 km. The mechanical transmission in the rear part of the hull consists of a change gear quadrant, a primary multiplate clutch unit with metallic friction pads, a manual gearbox with five forward gears, two multiplate planetary steering clutches with band brakes and two in-line final drive groups. The chassis has four twin rubber-tyred road wheels with