December 20, 2011:
So far, over 9,000 American M-1 tanks have been produced and most of them subsequently updated at least once. But the army, seeking to save a billion dollars, sought to close the plant that builds and modifies the M-1. The closure would be for three years, and when it was reopened there would be a backlog of upgrades and parts orders to fill to keep the plant open until, perhaps, an M-1 replacement comes along.
Politicians and the operators of the plant sought to keep the plant open in order to save jobs, votes, and operating profits. Thus in a largely political decision the plant appears to be getting the money (from the taxpayers) to stay open. How long the plant will remain in business is uncertain, as is the future of the M-1 tank.
For the immediate future, the M-1 plant will be needed because the army is planning to maintain its M-1 tank fleet (some 7,000 of them) for another twenty years. There is no replacement in sight and the chances of getting money for a replacement design are, for the near term, slight. The M-1 has already been in service for over two decades and may become the first MBT (main battle tank) design to stay in service for half a century. Technically, some World War II tanks achieved that dubious goal but not in the service of a major power.
The electronics on the M-1 have undergone several upgrades so far, in addition to the larger main gun. More equipment has been added for urban warfare (an outside phone, cameras, reactive armor side panels, thermal sights and shields for the external machine-guns) and new ammo types for the main gun have been developed. A major enhancement was depleted uranium armor, which made the M-1 virtually invulnerable from the front.
The one remaining item in need of improvement is the 1500 horsepower gas turbine engine. Improvements here included electronic monitors on many engine components, an electronic logbook (to record all pertinent engine activity), and a maintenance program that makes the most of all this data. If the engine is monitored closely and constantly, it's possible to carry out maintenance in a more timely (before something fails) manner. The army would also like to develop an improved (more efficient and less expensive to maintain) engine, but that is also a costly item they can't afford at the moment.
New anti-tank weapons are always being developed and the army wants to at least be able to afford new gear to deal with new threats. One threat that is currently ignored is top attack warheads (that put a shape charge type attack against the thin top armor). There are also new types of mines and electronic threats. If the M-1 is to survive for half a century it will have to evolve, as well as endure.
The M-1 Abrams tank is considered the best combat proven tank in the world. But there are many different models of M1s, which vary considerably in their combat capability. The earliest model is only about half as capable as the most recent SEP model. The first of 3,273 M-1 Abrams tanks was produced in 1978. This version had a 105mm gun. The first of 4,796 M1A1s (with a 120mm gun and depleted uranium armor) was produced in 1985 (plus 221 for the U.S. Marines and 555 co-produced with Egypt and another 200 M1A1s for Egypt). Production of the M1A2 (with improved fire control systems) began in 1986, with 77 for the US Army, 315 for Saudi Arabia, and 218 for Kuwait. Another 600 M1s were upgraded to M1A2 standards. Deliveries of these upgrades began in 1998. In 2001 the army began to upgrade 240 M1A2 tanks with better thermal imaging and fire control equipment as well as communications and computer equipment that would allow tanks to operate a full color "battlefield internet" with each other as well as headquarters and warplanes with similar equipment. The army upgraded 700 tanks to the M1A2SEP (System Enhancement Package) standard and built another 240 new M-1A2SEP vehicles.
There were other upgrades, after the 2003 invasion of Iraq, for urban warfare. Hundreds more M-1s had battle damage repaired and upgrades installed at the same time.