LAST OF THE PATTONS

The venerable M60 was standardized in March 1959 by the US Army, and entered production as the world’s first purpose-designed production Main Battle Tank. Some will argue that the Centurion, which was the first to carry the L7 105mm gun, could hold the title of the first Main Battle Tank, but it was initially designed as a cruiser tank, became a Medium Gun Tank when the 20-pdr was developed, and subsequently most were retrofitted with the 105mm gun to become Main Battle Tanks, often five to ten years after manufacture. The M60 series were expected to serve the Main Battle Tank role right off the drawing board.

Over 15,000 M60 series Main Battle Tanks were produced and the type went on to serve the USA into the 1990s. It beat the Chieftain, Leopard and AMX30 into service by five or six years and it continues in use in many armies right up to the present day. It bore the classic features of a lineage that stretched back to the M26 of 1944: a powerful main armament, heavy armour and good mobility.

The M60 earned its reputation as an effective family of combat tanks that bested the T55 and T62 in most encounters during the 1973 Yom Kippur war. This war made Continental Europe’s tank designers re-examine their design priorities and confirmed the importance of protection and firepower in American tank design. Its gun proved effective against any opponent it was called upon to fight. The M60’s excellent powertrain proved adaptable and was widely adopted in Israeli designs to improve tanks like the Centurion and to power their own Merkava.

The M60 program also yielded many improvements that were then applied to the M48A3 and M48A5 to keep older vehicles in service for decades. By any measure, the M60 was a successful tank design, one of the finest of the Cold War era, but one seldom recognised for its overall excellence.

The T95, the T60, and M60.

In the mid-1950s the United States Army was developing a lighter, more powerfully armed, more mobile and better armoured successor to the M48, itself a newly standardised medium tank. This was the T95, a visionary design with tremendous potential, and one that incorporated a great deal of new technology. The T60 was a modernisation of the M48A2, developed from a United States Army requirement for a lower risk medium weight tank alternative to the T95 program and was instituted in mid-1957. The objective of the T60 program was to bring a universal or Main Battle Tank into service with significant improvements over the existing M48A2 within a short time and employing available technology (and M48 derived components) wherever possible. The Main Battle Tank concept was intended to replace the M48 Medium Tank and M103 Heavy Tank with one heavily armed, highly mobile battle tank in the 40 to 55-ton range. The T60 was not originally expected to supersede the T95 program, but rather to supplement the existing M48 fleet as a advanced T95 was still expected to be produced and brought into service in the early 1960s.

The fundamental advantages enjoyed by the T95 over the M48A2 lay in its use of a diesel engine and in its superior fire power. The Army Bureau of Budget saw the M48 series as costly to operate and in need of modernisation or replacement as soon as possible. The quickest means of improving the situation was to replace the M48A2’s gasoline engine with a related Continental product, the AVDS-1790-2, which was simple to place in production and was a relatively mature design. The 750 HP engine was mated to an effective transmission, the CD-850-6, which gave the vehicle far better fuel economy than the M48A2 and a range of nearly 500km.

In 1958 the decision was taken to develop an American version of the Royal Ordnance L7 105mm gun, which became the T254. The British 105mm gun had been developed during the 1956-57 scare caused by the inspection of a T54 on the British embassy grounds in Budapest during the Soviet intervention in 1956. It had been achieved by the simplest of means-by increasing the bore of their existing QF 20-Pounder, an 83.4mm gun of similar dimensions to the M48’s US 90 mm M41 gun. The T254 was adopted as the M68 after extensive testing by the US Army in 1958, and the M116 gun mounting was adapted to the M48A2 turret casting. The M48A2C was still in production at the time and extensive testing was accomplished on modified M48A2s to develop the new tank. This choice of gun simplified the T60’s development considerably (although many changes to the M48A2 turret to suit the T60 were required, including a larger cupola ring).

Like the M48 series the T60 would employ an enclosed commander’s cupola, albeit one much larger than the M1 cupola fitted from the M48A1 onwards- a feature that production M60s retained right up to retirement from American service in the 1990s. The T60 turret’s frontal armour (as per the M48A2C) was a maximum of 180mm thick and 54 105mm rounds could be short- term solution to getting an effective counter to the Soviet T54 into service. At the time the T60 program started, the more carried for the main armament.

The T60’s cast hull was also based on the general layout employed on the M48A2, with some significant alterations. The most noticeable feature was the adoption of a flat glacis slope, compared to the rounded hull front seen on tanks like the M103 and M48 series. The T60’s hull’s frontal armour layout was roughly 100mm thick, and to save weight aluminium was used extensively for the road wheels. The driver, located in the middle of the front of the hull, enjoyed the same ease driving the T60 as its predecessor the M48. A floor escape hatch was provided immediately behind his seat.

The T60 was intended to be able to move and fight at night and was built with night driving in mind right from the start. The driver was provided with three periscopes, the middle of which could be replaced with a M24 infrared vision device. It carried a large Xenon light projector on the gun mantlet in a similar installation to the Crouse Hinds searchlight carried on the M48A2 and infrared sights were provided for the gunner and commander.

The T60 designation was changed to XM60 during the last months of 1958, and was standardised as the M60 in March 1959. It was ordered into production by the end of the year, carrying the Patton nickname used on the M47 and M48 forward, but was never officially to bear that name. The first 360 M60s were built in Delaware at the Chrysler Newark plant, and nearly 1700 more were manufactured at the Detroit Tank Plant.

M60A1

The first M60s entered service at the end of 1960. With the M60 in production, the next two years were spent adapting the best features of the T95’s turret to the M60 design, which resulted in the M60A1, first produced in mid-1962. An estimated 12,000 M60A1s were built and the type remained in production for about two decades (the monthly deliveries increasing after 1973 in response to the need to have a reserve of vehicles in case of crisis or war). The new turret had a maximum frontal armour thickness of 250mm, and was longer, with more crew space. There was increased stowage for 58 rounds of 105mm ammunition. The M60A1 introduced a 120mm thick glacis, an improved powertrain, improved crew positions and an improved suspension. Last of all, the M60A1 introduced new fire controls and improved combination (day and infrared) sights for the commander and gunner. This was the definitive version of the M60 family, which retained the optical rangefinder system of the M60 in improved form, but it still lacked an effective gun stabilisation system.

At around the same time that the M60 entered production, the T95 program was sidelined and eventually cancelled. The M60’s introduction also speeded the M103 heavy tank into retirement, except in the United States Marine Corps (where it was adopted with the significant substitution of the M60’s AVDS-1790 engine and cross-drive transmission). The M48A3 was largely improved as a result of the M60’s component and drivetrain development. It was improved subsequently in the 1970s into the M48A5 as the M60A1 underwent modernisations. 

The adoption of the L7 gun in the UK and its modification for American use as the M68 was a fundamentally important event, because it caused nearly every army that benefitted from American generosity in ammunition production to adopt compatible L7 or M68 based weapons either produced by the British, in the USA or under license from either nation. This influenced the adoption of this type of 105mm gun across nearly all the NATO nations for tanks introduced in the 1960s (with the exception of the French, although the British ironically retired their 105mm armed Centurions between 1967 and 1972 in favour of the Chieftain armed with an L11 120mm rifled gun). The M60 series was adopted in Italy, Israel, Spain, Greece, Turkey and many other friendly nations. The 1970s saw many incremental improvements added during the M60A1 production run and to vehicles which were rebuilt. The most significant came in 1972, a gun stabilisation system to give the M60A1 a fire on the move capability at long last. Besides the add-on gun stabiliser other improvements included new tracks and top-loading air cleaners.

M60A2

The M60A2 was the problem child of the M60 family, with an exceptionally long development time complicated by the fact that its main armament was beset with teething problems. The T95 was succeeded in the US developmental pipeline by the MBT70 concept and here American-West German co-production and co- development proved extremely difficult to coordinate. The MBT70 pursued between 1963 and 1971 was based on innovative, high risk technology and the armament system chosen to arm the American version spilled over into both the air-transportable tank concept (M551)and into the M60 program.

The Ford MGM51 Shillelagh Guided Missile Gun system chosen to arm the US MBT70 was adapted to a special turret designed to be mounted on a standard M60A1 hull in 1964 as the M60A1E1. The MGM51 employed an infrared guidance system, which proved difficult to perfect and difficult to adapt to an MBT fire control system. It also had tactical limitations in an armoured battle. The Shillelagh missile was a weapon that required line of sight control throughout its flight onto its target, which required the gunner’s full concentration at the expense of any sudden threat or any subsequent target acquisition. Other problems were encountered in the combustion of the 152mm conventional round’s cases intended for use when not engaging enemy MBT targets. The cost of the war in Vietnam impacted many weapon systems in the late 1960s. It also highlighted many problems with the 152mm/ Shillelagh system deployed with the M551s. The system’s reputation was sullied- and missile launching tanks came to be viewed with derision by armored corps officers as technical problems piled up. Full resolution of the issues associated with the Shillelagh were never achieved to a satisfactory level.

The Shillelagh-armed version of the M60 was tested over the course of several years and was ordered in 1971 (at around the same time that the MBT70 was cancelled). The turrets had been approved for production and paid for in 1966 and the hulls the following year, so it is unclear if the M60A2s were assembled from 243 existing stored turrets and hulls in 1971 or built from scratch. The M60A2 was a complex vehicle but it was eventually made to work. The Shillelagh missile, if successfully guided to its target, could defeat any tank of its generation, and the system could fire a range of powerful 152mm low velocity rounds when operating in the gun role. Additionally, the M60A2 suffered from a low rate of fire due to the need to purge the gun after each conventional round or the need to remove an obturator plate after each missile was fired. A standard stowage included 13 missiles and 33 rounds of 152mm ammunition of up to three different types.

Overshadowed by advances in gun development in the mid-1970s and by the success of simpler antitank missile systems like the TOW, the M60A2 was withdrawn from service in 1980. It only served in armored regiments for about six years, and it disappeared as soon as the M1 came on line in quantity in 1980. Its crews remember it as a vehicle that absorbed many man hours in maintenance, trouble shooting training and system checks to keep operational. Next to the new M1 Abrams, it might have seemed that the guided missile MBT was a technological dead end. Nearly all of the M60A2s were remanufactured and put to good use after retirement, some becoming bridgelayers, and others becoming M60A3s.

M60A1 RISE

The M60 and M60A1 were adopted throughout the United States Army’s armoured divisions in the early 1960s, and the M48 was supplemented and gradually replaced, except in the USMC and in Army armored units outside of Europe. It saw no action in the Viet Nam conflict, but was instead blooded against some of the best weapons the Soviets had developed in the 1973 Yom Kippur War in Israeli service. The M60A1 underwent a major upgrades from 1975 and 1977 onwards to improve key features, under the acronym RISE (Reliability Improved Selected Equipment). The original RISE program was oriented towards the improvement of the powertrain, introducing the AVDS-1790- 2C engine and improvements to the electrical system. The program was expanded in 1977 to improve turret systems, introducing passive night vision sights for the gunner and commander and new passive driving optics for the driver (these tanks being designated M60A1 RISE PASSIVE). The M60A1 RISE PASSIVE also introduced a fording kit to rival those in use in the Leopard 1 and the AMX30, which allowed the M60A1 to perform river crossings completely submerged.

M60A3

The last production version of the M60 gun tank was introduced in 1978, as the M60A3. This vehicle incorporated fire controls based on new ballistic computer and a new laser rangefinder. These were linked to a new gun stabiliser. The M60A3 thus brought the basic M60A1 configuration up to date for the 1980s, a decade where the arrival of new tanks like the M1, Leopard II and Challenger introduced advances like Chobham armour, hunter killer fire controls and 120mm main armaments. If the M60A3 was overshadowed by the technological marvel that the M1 represented, it honorably held the line with the M60A1 while enough M1s were built. When the Cold War ended the M60A1 and M60A3 disappeared rapidly from the US inventory. Some 5000 M60A1s were remanufactured as M60A3s by that time and the type was very well regarded by its crews.

Conclusion

Over the years some have derided the M60 series because the M68 gun wasn’t quite as powerful as the Chieftain’s L11 120mm, or because it wasn’t as agile as the Leopard or AMX30. It has been criticized for its high silhouette and for its 51- ton weight in some quarters. It cannot be argued that it proved to be a fine combat vehicle and one that earned its spurs the hard way-on the battlefield.  The M60 continues to defy its detractors and is still in service in many countries. Modern upgrades for the venerable M60A1 and M60A3 range from 120mm main armament kits to extensive passive and active armour upgrades, as well as a whole range of improved optics and fire controls in keeping with modern electronic advances. As such, the M60 soldiers on, a remarkable feat of longevity and a tribute to its sound design.

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