of the KV family of tanks in mass production, and was replaced by the ISU-152 on the ChKZ production lines in December 1943. The exact number of SU-152s produced differs even in Russian sources, with the most common figures being 670 or 704. The SU-152s that survived World War II were withdrawn from Soviet Army service in 1958. Construction and design The SU-152 followed the same, fully enclosed casemated design as most other Soviet self-propelled guns. The fully armoured hull was divided into two compartments: one for the crew, gun, and ammunition in the front of the hull, and one for the engine and transmission in the rear. The hull was welded from rolled armour plates of different thickness — 75, 60, 30 and 20 mm. The front hull and superstructure armour plates were sloped for better vehicle protection, while side armour was vertical. Lower front hull and rear armour plates were cylindrical, and relatively complex in their method of production. The ML-20S gun-howitzer was mounted slightly to the right of centre with a limited traverse in a range of 12 degrees. Three of the crew were to the left of the gun, with the driver to the front, then the gunner and lastly the loader. The vehicle commander and breech mechanism operator were to the right. The suspension consisted of 12 torsion bars for the six road wheels (each 600 mm in diameter) on each side. The drive sprockets were at the back. Each track was made up of 90 stamped links, each link of 608 mm width. The normal distance between two connected links was 160 mm. There were three internal fuel tanks, two in the crew area and one in the engine compartment, for a total capacity of 600–615 litres. These were usually enhanced by four unconnected external fuel tanks, which could hold an additional 360 litres of fuel. A 24-volt electrical power supply came from a 1 kW GT-4563A generator with a RRA-24 voltage relay regulator unit and four 6STE-128 accumulator batteries with a total capacity of 256 ampere-hours. This electrical equipment was common in contemporary Soviet armoured vehicles. The generator and accumulator batteries fed all other electrical equipment — the ST-700 electric starter motor, a radio set, an intercom, external and internal lights, and illumination of gunsight scales. For observation from the interior, all roof hatches had periscopes along with two gun sights: the telescopic