The M26 Pershing is a heavy tank, later designated as a medium tank (Tank, Medium, M26),Autor: Unknown. CHARACTERISTICS - Tank, Medium, M26. 4 pages. Unknown date formerly used by the United States Army during the early years of the Cold War. It was used in the last months of World War II during the Invasion of Germany and extensively during the Korean War. The tank was named after General of the Armies John J. Pershing, who led the American Expeditionary Force in Europe during World War I.
The M26 was intended as a replacement for the M4 Sherman, but a prolonged development period meant that only a small number saw combat in Europe. Based on the criteria of firepower, mobility, and protection, US historian R. P. Hunnicutt ranked the Pershing behind the German Tiger II heavy tank, but ahead of the Tiger I heavy and Panther medium tanks. It was withdrawn in 1951 in favor of its improved derivative, the M46 Patton, which had a more powerful engine and more reliable transmission and an advanced suspension. The lineage of the M26 continued with the M47 Patton, and was reflected in the new designs of the later M48 Patton and M60 tank.
Production history
Development The M26 was the culmination of a series of medium tank prototypes that began with the T20 in 1942, and it was a significant design departure from the previous line of U.S. Army tanks that had ended with the M4 Sherman. Several design features were tested in the prototypes. Some of these were experimental dead-ends, but many became permanent characteristics of subsequent U.S. Army tanks. This series of prototype vehicles began as a medium tank project that was similar to, but more modern than the recently introduced M4 Sherman, and ended several years later as the U.S. Army's first operational heavy tank.
Improving on the M4 The U.S. Army's first lineage of tanks evolved from the M1 Combat Car and progressed to the M2 Light Tank, M2 Medium Tank, M3 Lee, and finally the M4 Sherman. These tanks all had rear-mounted Continental air-cooled radial aircraft engines and a front sprocket drive. This layout required a driveshaft to pass under the turret, which increased the overall height of the tank, a characteristic shared with German tanks of World War II that also used this layout.Jentz 1995, pp. 14–18. In the case of designs for the Panther tank, the rear engine and rear sprocket driven Daimler-Benz VK 30.01 proposal was about lower overall than the rear engine/front sprocket MAN VK 30.02 proposal. The large diameter of the radial engines in M4 tanks added to the hull height. These features accounted for the high silhouette and large side sponsons that were characteristic of the M4 lineage.
In the spring of 1942, as the M4 Sherman was entering production, U.S. Army Ordnance began work on a follow-up tank. The T20 tank reached a mock-up stage in May 1942, and was intended as an improved medium tank to follow the M4. An earlier heavy tank, the M6, had been standardized in February 1942, but proved to be a failure. The U.S. Army had no doctrinal use for a heavy tank at the time.
T20
The T20 was designed to have a more compact hull than the M4. The Ford GAN V-8, a lower silhouette version of the GAA engine used in later variants of the M4, had become available. The engine had originally been an effort by Ford to produce a V-12 liquid-cooled aircraft engine patterned after the Rolls-Royce Merlin, but failed to earn any aircraft orders and so was adapted as a V-8 for use in tanks; use of this lower profile engine together with the choice of a rear transmission and rear sprocket drive layout made it possible to lower the hull silhouette and eliminate the side sponsons.
The T20 was fitted with the new 76 mm M1A1 gun, the 3-inch M7 was considered too heavyChamberlain, Gander – Anti-Tank Weapons, p 49. at about . New stronger steels Hunnicutt, R. P. – Armored Car: A History of American Wheeled Combat Vehicles., p 41 were used to create a weapon weighing about 1,200 lb (540 kg).Hunnicutt, R. P. – Stuart: A History of the American Light Tank, p 295-296. The 3 inch front hull armor was thicker than the front armor of the M4. The glacis plate slope was similar at 46°. The T20's overall weight was approximately the same as the M4.
The T20 used an early version of the horizontal volute spring suspension (HVSS), another improvement compared to the less robust vertical volute spring suspension (VVSS) of the early versions of the M4. Later prototypes of the M26 tested a torsion bar suspension, which became the standard for future U.S. tank suspension systems.
T22 and T23 The T22 series reverted to the M4 transmission because of problems with the early Torqmatic transmission used in the T20. The T22E1 tested an autoloader for the main gun and eliminated the loader's position with a small two-man turret.
Through much of 1943, there was little perceived need within the U.S. Army for a better tank than the 75 mm M4 Sherman, and so, lacking any insights from the rest of the Army as to what was needed, the Ordnance Department then took a developmental detour into electrical transmissions with the T23 series.
The electrical transmission was built by General Electric and had the engine driving a generator that powered two traction motors. The concept was similar to the drive system of the German "Porsche Tiger". It had performance advantages in rough or hilly terrain, where the system could better handle the rapid changes in torque requirements.
The electrical transmission T23 was championed by the Ordnance Department during this phase of development. After the initial prototypes were built in early 1943, an additional 250 T23 tanks were produced from January to December 1944. These were the first tanks in the U.S. Army with the 76 mm M1A1 gun to go into production. However, the T23 would have required that the army adopt an entirely separate line of training, repair, and maintenance, and so was rejected for combat operations.
The primary legacy of the T23 would thus be its production cast turret, which was designed from the outset to be interchangeable with the turret ring of the M4 Sherman. The T23 turret was used on all production versions of the 76 mm M4 Sherman as the original M4 75 mm turret was found to be too small to easily mount the 76 mm M1A1 gun. The first production 76 mm M4 with the T23 turret, the M4E6, was built in the summer of 1943.
T25 and T26
The T25 and T26 lines of tanks came into being in the midst of a heated internal debate within the U.S. Army from mid-1943 to early 1944 over the need for tanks with greater firepower and armor. A 90 mm gun mounted in a massive new turret was installed in both series. The T26 series were given additional frontal hull armor, with the glacis plate increased to . This increased the weight of the T26 series to over and decreased their mobility and durability as the engine and powertrain were not improved to compensate for the weight gain.
The T26E3 was the production version of the T26E1 with a number of minor modifications made as the result of field testing. In February 1945, the T26 was fielded in the European Theater, where its performance received early praise from Army Ordnance officials. The Army named the tank after Army General John J. Pershing when it was redesignated the M26 in March.
After the war After World War II, some 800 M26 tanks were upgraded with improved engines, transmissions, and the improved 90mm gun M3A1. These were designated as the M26E2 and later redesignated as M46 Patton.
Delayed production The M26 was introduced late into World War II and saw only a limited amount of combat. Tank historians, such as R. P. Hunnicutt, George Forty and Steven Zaloga, have generally agreed that the main cause of the delay in production of the M26 was opposition to the tank from the Army Ground Forces, headed by General Lesley McNair. Zaloga in particular has identified several specific factors that led both to the delay of the M26 program and limited improvements in the firepower of the M4:
1. McNair, who was an artillery officer, had promulgated the "tank destroyer doctrine" in the U.S. Army. In this doctrine, tanks were primarily for infantry support and exploitation of breakthroughs. Those tactics dictated that enemy tanks were to be engaged by tank destroyer forces, which were composed of lightly armored but relatively fast vehicles carrying more powerful anti-tank guns, as well as towed versions of these anti-tank guns. Under the tank destroyer doctrine, emphasis was placed only on improving the firepower of the tank destroyers, as there was a strong bias against developing a heavy tank to take on enemy tanks. This also limited improvements in the firepower of the M4 Sherman. The US Army Ground Forces that supported this doctrine got the approval of new TD projects, one of them using the same 90 mm gun, while at the same time they were blocking tank projects. 2. McNair established "battle need" criteria for acquisition of weapons in order to make best use of America's supply line to Europe by preventing the introduction of weapons that would prove unnecessary, extravagant or unreliable on the battlefield. In his view, the introduction of a new heavy tank had problems in terms of transportation, supply, service, and reliability, and was not necessary in 1943 or early 1944. Tank development took time, and so the sudden appearance of a new tank threat could not be met quickly enough under such criteria. 3. A sense of complacency fell upon those in charge of developing tanks in the U.S. Army because the M4 Sherman, in 1942, was considered by the Americans to be superior to the most common German tanks: the Panzer III and early models of the Panzer IV. Even through most of 1943, the 75 mm M4 Sherman was adequate against the majority of German armor, although the widespread appearance of the German 7.5 cm KwK 40 tank gun during this time had led to a growing awareness that the M4 was becoming outgunned. There was insufficient intelligence data processing and forward thinking to understand that an arms race in tanks was in progress and that the U.S. needed to anticipate future German tank threats. The Tiger I and Panther tanks that appeared in 1943 were seen in only very limited numbers by U.S. forces and hence were not considered as major threats. The end result was that, in 1943, the Ordnance Department lacking any guidance from the rest of the army, concentrated its efforts in tank development mainly on its major project, the electrical transmission T23. In contrast, the Russians and British were engaged in a continuous effort to improve tanks; in 1943, the British began development of what became the 51-ton Centurion tank (although this tank reached service just too late to see combat in World War II) and, on the Eastern Front, the tank arms race was emphatically underway, with the Soviets responding to the German heavy tanks by starting development work on the T-34-85 and IS-2 tanks.
From mid-1943 to mid-1944, development of the 90 mm up-armored T26 prototype continued to proceed slowly due to disagreements within the U.S. Army about its future tank needs. The accounts of what exactly happened during this time vary by historian, but all agree that Army Ground Forces was the main source of resistance that delayed production of the T26.