Authored By Dan Alex (Updated: 4/18/2016):
With that said, the M47 was a further development of the M46 Patton, which itself was a development of the wartime M26 Pershing (externally, the entire tank family line shared many similarities in their design). Classified as a medium tank, the M47 formed the backbone of US Army and NATO forces during those critical early years of the Cold War with its escalating arms race and limited conflicts. Intended to replace both the M4 Sherman and M46 Patton classes, the M47 graduated to become the long arm of NATO for decades to follow and was ultimately produced in 8,676 examples and fielded by some 21 nations across the globe - primarily throughout Europe, Asia and the Middle East. While charged to replace the M46, the M47 itself was quickly replaced in US service by the improved M48 beginning in the mid-1950s. However, it is of note that the M47 represented America's first true "all new" tank system developed since the days of World War 2.
The T42 and the Korean War
By the time of the Korean War in 1950, the mainstay force of the post-World War 2 US Army were the M26 Pershing and the M46 Patton tanks. The M46 itself was an interim solution meant to improve upon the drawbacks of the M26 - mainly in its underpowered engine (basically the same as found on the lighter M4 Sherman) and limited mobility. While the M46 fitted a better engine and improved reliability, it was still seen as nothing more than an interim solution for an all-new medium tank design was then in the works to known as the "T42". The T42 showcased a shapely, single-piece, molded turret and five double-wheeled medium-size road wheels to a track side fitted to a wide body hull. However, the ongoing war across the Korean Peninsula brought about the need for a quicker main battle tank solution without those inherent delays as found in a "ground-up" tank design program like the T42.
The M47 is Born
As a result, the turret developed for the T42 was mated to the existing (and proven) M46 chassis with the main armament of the M36 90mm being the gun of choice. The design went under the pilot (prototype) designation of "M46E1" of which only one example was constructed. The new tank then became known under the production designation of M47 (though it was theoretically the "Patton II", the M47 was never officially reported as such). The M47 underwent production at the Detroit Tank Arsenal and American Locomotive Company beginning in June of 1951 almost immediately. Despite this expediency, the 50-ton M47 would arrive too late to see combat actions in the Korean War - the very war that brought about the tank's construction - for the armistice between the North and South was drawn up in 1953. American service units were taking on delivery of the M47 beginning in the summer of 1952. However, delays in receiving the M12 optical rangefinders for the 90mm main guns played a role in the tank missing the war. In fact, M47s were not delivered to the region until August of 1958 - these replacing the M46s stationed there.
M47 armor was all-cast for both the turret and hull with a transverse bulkhead separating the crew from the engine. The crew was made up of five personnel that included the driver and assistant driver (bow gunner) in the forward hull and the tank commander, gunner and loader in the turret. The bow gunner and driver were allowed entry/exit via a pair of top-mounted hatches along the forward hull while the turret featured a further two hatches for the turret crew therein. The oblong turret, with its pointed front end and overhanging rear, was set in the forward portion of the hull and featured full 360-degree rotation with -5 to + 19 traverse for the 90mm main gun. Each track side was characterized by six double-wheeled road wheels and three track return rollers. Suspension was of the torsion bar variety.
Armament centered around the 90mm M36 series main gun of which 71 x 90mm projectiles were allotted. Secondary armament included a .50 caliber heavy Browning M2 air-cooled machine gun for anti-aircraft defense on a pintle mount along the turret roof and manned by the tank commander. This was further complimented by a co-axially mounted .30 caliber M1919A4 machine gun (controlled by the gunner) and an additional .30 caliber M1919A4 machine gun in a bow-mount for anti-infantry defense (the latter was later removed to make space for additional 90mm projectiles, therefore making the M47 the last American tank to feature the bow-mounted machine gun and its extra crew position).