artillery, transport 1.9 tonnes of cargo, or carry a half platoon of infantry. Most Soviet BTR-152s were powered by a six-cylinder ZIL-123 in-line water-cooled petrol engine developing 110 hp at 2,900 rpm. Those based on the chassis and components of the ZIL-157 utility truck utilized a slightly different ZIL-137K engine. There are several engine louvers on the front of the hull to prevent overheating; these could be safely closed for short intervals during combat, as long as the driver reduced speed and avoided overtaxing the vehicle. A BTR-152's gearbox comprised five forward gears and one reverse gear with a two-speed transfer box. Fifth gear had an overdrive. The suspension consisted of conventional leaf springs with hydraulic shock absorbers. In the late 1950s, a little over 200 BTR-152s were produced with enclosed hulls, as opposed to the traditionally open-topped design; these were designated BTR-152K and BTR-152K1. They were also known unofficially as "BTR-152 Model D" or "BTR-152 M1961" by some Warsaw Pact armies. The enclosed hull reduced situational awareness but allowed for the installation of central heating and an NBC overpressure system. Two hatches opening to the right were installed on the new roofline. The BTR-152 was originally armed with a single pintle-mounted 7.62mm SG-43 Goryunov (SGMB) medium machine gun, fed by 1,250 rounds of stored on-board ammunition. This was mounted behind the driving position. Additional 7.62mm general-purpose machine guns could be mounted on either side of the hull top as needed. The SGMB machine gun could traverse 45 degrees and elevate between -6 and +24 degrees. Some of the BTRs were fitted with single 12.7mm DShK or 14.5mm KPV heavy machine guns in place of the SGMB. Vehicles designated BTR-152A were ground support vehicles with limited air defense capability. BTR-152As carried twin KPVs in a ZPU-2 anti-aircraft mount. Variations included an Egyptian model with a Czechoslovak M53 Quad mounting for four DShKs, which were normally towed on a two-wheeled trailer, and some modified by the Palestine Liberation Organization to accept 23mm ZU-23-2 anti-aircraft guns. Because the original BTR-152 utilized the chassis and engine of the ZIS-151, it shared that truck's maintenance problems and poor cross-country mobility. Later variants, using ZIL-157 components, had more power and larger, single tires that reduced the vehicle's shortcomings but did not eliminate them. Serviceability and reliability remained low. Variants Former Soviet Union BTR-152 (1950) – Basic APC based on ZIS-151 truck, many of which would