A tank is a tracked, armored fighting vehicle designed for front-line combat which combines operational mobility and tactical offensive and defensive capabilities. Although power armor is frequently referred to as making people look like tanks, these armored behemoths fill a combat role power armor cannot. However, in the wasteland, they are exceedingly rare, especially in working order.
The Chimera is a heavily modified Alaskan mining rig that was upgraded by the People's Liberation Army to serve as a battle tank in the harsh conditions of the Alaskan theatre of war. The Chimera itself was originally a screw-propelled vehicle intended to negotiate harsh Alaskan terrain. The chassis rests on the screw, with each powered by a separate motor with plenty of clearance between them. A streamlined hull is mounted to the chassis, with a deployable mining rig resting in the middle of the vehicle. The low profile and organic shape make it easy for the Chimera to transverse the tundra in search of oil fields. It is not clear whether the Chimeras were actually developed by the Chinese, as voice clips intended for use in the game suggest their presence was a fantasy implemented by General Constantine Chase.
The United States military utilized heavy main battle tanks. The main battle tank is a behemoth that employs a pair of tracked chassis, with a single turret mounted on the top. Its key advantage is firepower: The main battle tank is equipped with a pair of large caliber kinetic cannons using conventional ammunition.
This tank is a M4 Sherman battle tank, which has seen extensive modification over the years since its initial service in World War II. Although woefully outdated by the 21st century, in the resource-deprived reality of the wastelands, it is a veritable juggernaut. It is heavy, yes, and very slow, yes, but the sloped steel armor makes it nigh invulnerable to most infantry weapons, short of explosives and anti-tank weaponry. It retains its primary 75mm gun mounted on a fully traversing turret, with a gyrostabilizer enabling the crew to fire with reasonable accuracy while the tank was on the move. However, the range of the gun was reduced severely when raiders tried to rebore the barrel and failed.
Gameplay article: none (mentioned in Fallout Tactics)
The United States military has also utilized heavy duty conventional main battle tanks. This "heavy tank" (wiki description) has a single tracked chassis, with a single turret mounted on the top. This model appears to have a single large caliber kinetic cannon using conventional ammunition and some sort of side mounted device.
The IS-2 was the heavy tank of the Soviet Union's Red Army in the late stages of World War II. The entire IS tank line was developed as a replacement of the aging and outdated KV tank series. Lighter, faster, and harder hitting than the old KVs, the IS was equipped with a 122mm gun capable of penetrating any German tank or fortification it came across and was primarily used as a breakthrough tank in assaults. The IS series saw new variants developed after the war but became obsolete after the emergence of the main battle tank concept. The Soviets retired the IS from service but continued its service in other communist countries.
Retaining many of the features of the Mark One through Five tank series, the Mark Eight nonetheless introduced a number of changes to the design, the most important of which was the introduction of compartmentalization, separating the working engine from the crew, shielding them against noise, fumes, and heat. Otherwise, it was a typical First World War line tank: Huge, slow - top speed was just 5.25 mph (8 km/h) - and poorly armored, though with a pair of 57mm guns it could project excellent firepower. It was originally intended for the 1919 offensive against the Central Powers, with initial production runs fielded in Europe as soon as possible, but delays caused it to enter service after the capitulation of the Central Powers. Ultimately, it failed to make an impression and all existing tanks were scrapped by 1940.
The M46 Patton started its life as an upgrade of the M26 Pershing and eventually developed into a new type of tank - one of the main medium tanks of the United States in the early stages of the Cold War (1949-1950s). Restricted primarily to United States service, its key upgrade was the replacement of the original power plant with the Continental AV1790-3 engine and Allison CD-850-1 cross-drive transmission and the 90mm M3 gun of the M26 Pershing into the M3A1 with bore extractor. Its only known period of service was during the Korean War.
The United States military utilized modern, conventional main battle tanks as late as 2066. It can be seen in a photograph from 2066 showing American troops moving against the Chinese in Alaska. It should be noted, however, that this is a slightly modified photo of a M46 Patton from the Korean War which has had a second tank added to it, and only appears once as a 2066 tank on a newspaper in a Fallout 3 official trailer.
↑Fallout Bible 0: "2067 The first suit of Power Armor is deployed in Alaska. While lacking the full mobility of future versions, this Power Armor is incredibly effective against Chinese tanks and infantry. Its ability to carry heavy ordinance becomes key in various localized conflicts, and it has the power to destroy entire towns without endangering the wearer. China rushes to create its own versions, but they are many years behind the United States."
↑The Lone Wanderer: "What exactly IS a Chimera?" Thomas Morgan: "Put simply, it's a co-opted mining rig that's been changed into an armored vehicle -- bigger and tougher than any tank we have in our arsenal. The Chinese fitted the vehicle with multiple weapons, reinforced the armor and outfitted them for long range." (DLC02LtMorgan.txt)
↑Original image was used as a photograph on the prop newspaper in the trailer.