M60 tank
The M60 is an American second-generation main battle tank. It was officially standardized as the Tank, Combat, Full Tracked: 105-mm Gun, M60 in March 1959. Although developed from the M48 Patton, the M60 tank series was never officially christened as a Patton tank. It has been called a "product-improved descendant" of the Patton tank's design. The design similarities are evident comparing the original version of the M60 and the M48A2. The United States fully committed to the MBT doctrine in 1963, when the Marine Corps retired the last heavy tank battalion. The M60 tank series became the American primary main battle tank during the Cold War, reaching a production total of 15,000 M60s. Hull production ended in 1983, but 5,400 older models were converted to the M60A3 variant ending in 1990.
The M60 reached operational capability upon fielding to US Army European units beginning in December 1960. The first combat use of the M60 was by Israel during the 1973 Yom Kippur War, where it saw service under the "Magach 6" designation, performing well in combat against comparable tanks such as the T-62. The Israelis again used the M60 during the 1982 Lebanon War, equipped with upgrades such as explosive reactive armor to defend against guided missiles that proved very effective at destroying tanks. The M60 also saw use in 1983 during Operation Urgent Fury, supporting US Marines in an amphibious assault on Grenada. M60s delivered to Iran also served in the Iran–Iraq War.
The United States' largest deployment of M60s was in the 1991 Gulf War, where the US Marines equipped with M60A1s effectively defeated Iraqi armored forces, including T-72 tanks. The United States retired the M60 from front-line combat after Operation Desert Storm, with the last tanks being retired from National Guard service in 1997. M60-series vehicles continue in front-line service with a number of countries' militaries, though most of these have been highly modified and had their firepower, mobility, and protection upgraded to increase their combat effectiveness on the modern battlefield.
The M60 has undergone many updates over its service life. The interior layout, based on the design of the M48, provided ample room for updates and improvements, extending the vehicle's service life for over four decades. It was widely used by the US and its Cold War allies, especially those in NATO, and remains in service throughout the world, despite having been superseded by the M1 Abrams in the US military. The tank's hull was the basis for a wide variety of Prototype, utility, and support vehicles such as armored recovery vehicles, bridge layers and combat engineering vehicles. Egypt is the largest operator with 1,716 upgraded M60A3s, Turkey is second with 866 upgraded units including M60T tanks in service, and Saudi Arabia is third with over 650 units.
Development
Impetus
The United States entered a period of frenzied activity during the crisis atmosphere of the Korean War, when America seemed to lag behind the Soviet Union in terms of tank quality and quantity. Testing and development cycles occurred simultaneously with production to ensure speedy delivery of new tanks. Such rapid production caused problems but the importance given to rapidly equipping combat units with new tanks precluded detailed testing and evaluation prior to quantity production.The M47 Patton entered production in 1951 and was used by the United States Army and Marine Corps but ongoing technical and production problems kept it from serving in the Korean War. The M48 Patton tank entered US service in 1952 but its early designs were deemed unsatisfactory by Army Field Forces. The improvements to the M48 focused on improving the 90 mm main gun and fire control systems while simultaneously exploring the development of silicas glass composite armor and autoloader systems. The tank continued further development through 1955 in conjunction with its simultaneous mass production. The course of its development during the mid-1950s was the source of widespread debate among Congressional Budget Oversight committees.
The T95 program, which began in 1955 was intended to supersede the M48, featured a host of innovative and experimental components such as its 90mm smoothbore T208 cannon rigidly affixed to its turret, experimental X-shaped engine design using a vapor-cycle power plant fueled by hydrocarbons, composite armor and infrared rangefinder. The burden of developing them, however, slowed the overall program to a crawl.
During the Hungarian Revolution of 1956, a Soviet T-54A medium tank was driven onto the grounds of the British embassy in Budapest by the Hungarians in November. After a brief examination of this tank's armor by British military attaché Lt Col Noel Cowley, it was concluded that the 20-pounder was apparently incapable of consistently defeating its frontal armor with High-Explosive Anti-Tank or Armor-Piercing Capped ammunition. Its 100 mm gun was a significant advancement over the weapon of the T-44.
There were also rumors of an even larger 115 mm gun in the works. These events spurred the United Kingdom to begin upgrading existing tanks with a 105 mm high-velocity rifled gun in 1958, the Royal Ordnance L7 to keep the Centurion viable against this new Soviet tank design. The United States responded by starting development of the XM60 tank in September 1957. This new tank design incorporated many Army Combat Vehicle committee improvements to the M48A2, chiefly the use of diesel engines to increase its operational range and the use of a more powerful main gun.
Choice of components
M68 105 mm main gun
The main gun was chosen after a comparative firing test of six different guns carried out on the Aberdeen Proving Ground in 1958. The factors evaluated were accuracy, lethality of a hit, rate of fire and penetration performance.An M48A2C was fit with the 90 mm M41 and tested with the new T300E53 HEAT round. A smoothbore version of the 90 mm, the T208E9, was mounted on the T95E1 tank and tested the T320E62 Armour-Piercing Discarding Sabot round. An American variant of the British Royal Ordnance L7 tank gun, under the US designation 105 mm T254E1, was mounted on the T95E2 and tested with British APDS ammunition. Finally, two versions of the 120 mm gun from the M103 were trialed, the existing model and a lightened variant known as T123E6 which was mounted on the T95E4.
The T123E6 was preferred by the Ordnance Department because its ammunition, the same as that for the M58 gun, was already at an advanced state of development. However, the ammunition was in two parts, shell and propellant bag, which required significant time to load. In the M103 this was addressed by adding a second loader, but a medium tank would not have the internal space needed for another crewmember and the firing rate would suffer as a result. In testing it demonstrated a maximum rate of 4 rounds per minute vs. the T254's 7 rpm.
Based on these tests, the 105 mm T254E1 was selected, modified to the T254E2 and standardized as the "Cannon, 105 mm Gun, M68". It used a vertical drop breechblock instead of the T254E1's horizontal sliding breechblock. Until American-made barrels could be obtained with comparable accuracy, British X15/L52 barrels were to be used. US built XM24/L52 barrels fitted with an eccentric bore evacuator were used for the M60-series starting in June 1959 but retained interchangeability with the British X15/L52 barrel.
All of the US guns and XM24 barrels were produced at the Watervliet Arsenal, NY and the gun mounts were manufactured at the Rock Island Arsenal, IL. Because the evacuator was positioned lower on the gun's barrel US M68 guns were fitted with an eccentric bore evacuator instead of a concentric model in order to provide more clearance over the rear deck.
The M68E1 gun shares the same firing characteristics as the M68. It featured several design improvements including an updated gun hydraulic configuration, a stabilization upgrade for the gun, a gun elevation kill switch for the loader, improved ballistic drive allowing the accurate firing of long dart penetrators and other component refinements.
The gun is capable of using a wide range of ammunition including APDS-Tracer , Armour-Piercing Fin-Stabilized Discarding Sabot-Tracer , APFSDS Depleted Uranium , HEAT-FS, APDS dummy and target practice rounds, High Explosive Plastic / High-Explosive Squash Head , white phosphorus and canister rounds. Barrels with thermal sleeves were used starting in 1973.
Both the original M60 variant as well as the initial configuration of the M60A1 used the M68 gun. Additionally, many M48A3s armed with a 90 mm gun that were in service with the Army National Guard were retrofitted with the M68 gun during the mid-1970s and redesignated as the M48A5. This was done to maintain training levels of ARNG units as well as using a commonality in ammunition amongst tanks.
M60A1 RISE Passive tanks built after 1977 and all M60A3 tanks were armed with the M68E1 variant of the gun. It had an improved ballistic drive to allow for accurate firing of the M735 APFSDS ammunition. Most M60A1 RISE tanks were retrofitted to this standard by applying the M735 Cam update from the M60A1 PIP Turret Update Kit.
Armor
Composite armor made with fused silica glass sandwiched between plates of steel were intended to be fitted to the hull. This led to a redesign of the front of the hull into the shape of a flat wedge, instead of the M48's elliptical front, as it simplified the installation of this armor. It was also envisioned that the T95E6 turret was to be constructed solely with this special armor. The US Army Ordnance Tank Automotive Command and the Carnegie Institute of Technology began development of the armor in November 1952 at Fort Belvoir VA as Project TT2-782/51 using examples of the T95 tank to conduct the ballistics testing.This composite armor provides protection against HEAT, HEP/HESH and HE rounds. However, field repaired panel castings suffered a loss of kinetic energy protection. Limitations in manufacturing capacity and the added cost led to this armor being dropped by November 1958 and all M60-series tanks were protected with conventional steel armor but the tank retained the capability to employ armor panels.
The M60 was the last tank to feature an escape hatch under the hull. The escape hatch was provided for the driver, whose top-side hatch could easily be blocked by the main gun.
There were two versions of hulls used for the M60-series. The M60 hull had a straight slope and beak compared to the earlier M48's rounded one. The hull bottom had a strong boat-like appearance with a pronounced recess between the upper tracks and external suspension arms and one shock absorber on the first roadwheel pair. The armor was improved, at 6 inches on the front glacis and mantle of solid rolled homogeneous armor, while it was 4.3 inches on the M48. The first prototype hulls did not have shock absorbers and were briefly named M68 in late 1958 before the Ordnance Department renamed it the M60 in March 1959. This hull version was used only on the original M60 variant and early M728 Combat Engineer Vehicles and M60 Armored Vehicle Launched Bridges. This hull model was in production from 1959 to 1962.
The M60A1 hull has basically the same visual characteristics, the noticeable difference was the addition of a second shock absorber at the second roadwheel pair and was also accompanied by a slight relocation of the first return roller. These modifications were needed due to the increased weight of the M60A1 turret as well as the additional hull armor. This hull model was used on the M60A1, M60A2 and M60A3 models of the M60-series as well as the M728A1 CEV and M60A1 AVLB. It was in production from 1962 to 1983.
The M60-series went through a progressive turret design scheme during its production life with four different turrets being manufactured for the M60-series. The T95E5 turret used on the M60 was hemispherically shaped and bore a strong resemblance to the M48 Patton. The M60A1 was the first version to employ the newly designed T95E7 turret with a redesigned bustle increasing the number of rounds for the main gun to 63. The M60A2 featured a specially designed turret for the M162 gun/missile launcher that greatly reduced the frontal arc in comparison to the M60A1's T95E7 turret. The M60A3's turret was similar to the A1's but with increased armor protection for the frontal arc and mantlet in an effort to provide additional protection of the turret's hydraulics system.