A BattleMech (often abbreviated 'Mech, although that could technically also refer to IndustrialMechs) is an armored combat vehicle of roughly humanoid shape, some 10 to 20 meters tall and typically massing from 20 to 100 tons. 'Mechs are best suited for ground combat, although they are also capable of operation underwater, in vacuums and/or in zero-g environments (space).
A single 'Mech can easily destroy a city block. A BattleMech's only true equal is another 'Mech—artillery, aircraft, and tanks are disadvantaged against them without BattleMech support or a strong advantage in numbers.
The first BattleMech was the Mackie, often described as a 100-ton box with legs. It was developed in 2439 by the Terran Hegemony, first deployed in 2443, and produced throughout the rest of the Inner Sphere after the BattleMech construction plans were stolen in 2455. Hundreds of distinctive BattleMech models have emerged since then.
The Succession Wars plunged the Inner Sphere into centuries of interstellar warfare soon afterwards. In this technological and cultural dark age of Lostech, the Successor States of humanity soon fought with 'Mechs and other equipment that was literally decades, if not centuries, old and in a sorry state of repair. Ancient automated factories continued to produce BattleMechs even when their technology was not understood anymore. Over time, equipment shortages, system failures and similar problems sparked innumerable variants of the classic designs. Field modifications and makeshift repairs became commonplace.
During the the invasion of the Clans in 3050, the Inner Sphere got its first look at technology advanced even beyond the lost technology of the old Star League. Enstranged from the rest of humanity for centuries, the invaders fielded unknown BattleMech designs that became known under different names among the Clans and in the Inner Sphere, respectively. For example, the Clan Timberwolf was nick-named the Mad Cat because the battle computers of Inner Sphere 'Mechs alternated between Marauder and Catapult when they tried to identify the unknown design; the Clan Summoner was dubbed as the Thor by House Steiner's forces because of its deliverance of "thunder and lightning" by its Autocannon and PPC, and the Dire Wolf became known as Daishi ("great death") among forces of House Kurita. The Mad Dog even received different names, being dubbed Vulture by the Federated Commonwealth and Hagetaka in the Draconis Combine.
 BattleMech Construction
BattleMechs are built around an internal structure resembling a skeleton. The musculature (actuators) consists of myomer, an artificial polymer fiber which contracts in the presence of an electrical current. The artificial skeleton and musculature, combined with a large gyroscope system, provides stability for the BattleMech and allows for bipedal movement. Some 'Mechs have jump jets that provide thrust bursts for short leaps.
The power required for the actuators, weapons, and other systems is provided by a Fusion Engine mounted in the torso. Although all 'Mechs have heat sinks, heat buildup is a frequent problem. Intense combat action can lead to overheating that puts physical strain on the pilot, and may even cause an emergency reactor shutdown.
Most BattleMechs copy the human form to an extent, which is the deciding factor in their versatility and ultimately, their superior combat performance. The entire system is controlled by a pilot wearing a neurohelmet which links the 'Mech's central computer to the pilot's sense of balance and nervous system. Augmented by a combination of throttle, joystick, and dual pedal system, the 'Mech pilot controls the BattleMech like an extension of his own body, comparable to a very large combat suit. Many 'Mechs have fully articulated hands that can be used to climb or grab items.
OmniMechs, a concept introduced by the Clans and later adopted by the Successor States of the Inner Sphere, feature hardpoints with interchangeable weaponry whereas classic BattleMechs have a fixed configuration.
Designed as combat vehicles, BattleMechs are modular to an extent and thus relatively easy to repair and maintain. Even throughout the Lostech era of the Succession Wars, scavenged battlefield salvage could keep them operational despite their technology not being understood anymore.
 Chassis Types
Covering the vast majority of the types of BattleMechs, bipedal 'Mechs come in two types:Wasp, Phoenix Hawk, Warhammer, Atlas and Summoner (Thor). Locust, Catapult, Marauder, and Timber Wolf (Mad Cat).
 TripodalColossal class Ares 'Mechs which appeared in the early 3130s. The Hedgehog was previously mentioned as a tripodal 'Mech from the Star League era, having allegedly been introduced in 2602, but it is not considered canonical.
 QuadrupedalQuad 'Mech uses its "arms" for legs which gives these designs some additional stability and maneuverability (such as sidestepping, also known as lateral shift movement). The concept was much maligned for sacrificing the overall versatility of BattleMechs and the early designs, notably the Scorpion and the Goliath, proved flawed, being notoriously difficult to maintain and highly susceptible to breakdowns. It was only around the year 3060 that improved technology led to new quadrupedal 'Mech designs, although the stigma associated with the general concept still lingers. Bipedal BattleMechs remain the vastly more common 'Mech.
 Land-Air 'Mech (LAM)LAM) can transform from a regular BattleMech form into an Aerospace Fighter, or an intermediate form referred to as LAM Mode. While performing just like a conventional BattleMech or Aerospace Fighter in the respective form (to the point of being kept in either 'Mech bays or fighter hangars aboard DropShips), in LAM Mode these 'Mechs can quickly traverse great distances, giving them a tactical advantage in ground combat although their real niche apparently is reconnaissance. However, their delicate technology is unduly susceptible to damage and the combat performance of Land-Air 'Mechs fell short of expectations by a long margin, especially considering their exorbitant production and maintenance costs. Land-Air 'Mechs were only produced in small numbers and the ability to maintain and repair (or even produce) them was largely lost early on in the succession wars. The concept quickly faded into obscurity from a combination of small numbers, maintenance shortfalls and combat attrition.
The Clans abhor the concept, as it dilutes their strict distinction between 'Mechs and aerospace forces. Clan Nova Cat famously took great care to raze the last remaining LAM factory to the ground. Only Clan Jade Falcon is known to have delved into LAM research, but the project was terminated in 3059 after only two prototypes (Evil Twin One and Evil Twin Two) had been built; the scientists found the Land-Air Mechs to be too unstable to field in normal combat.
Although it is technically possible to build "ultralight" 'Mechs of 15 or even 10 tons, most 'Mechs in this range are IndustrialMech designs. Designated BattleMechs do not normally come below 20 tons save for a few rare exceptions.
The arguably most famous ultralight design (and also the first that was ever published) is the FLE-14 subvariant of the Flea, massing 15 tons while most other variants weigh in at 20 tons.
Ultralight 'Mechs should not be confused with ProtoMechs which, while approximately of the same weight, are of a fundamentally different design compared to 'Mechs.
All 'Mechs weighing from 20 up to 35 tons are classified as "light". Their skeleton can only carry limited armor, but the higher efficiency of smaller fusion reactors means that light 'Mechs benefit from superior mobility. They are typically fast but lightly armed and armored. These 'Mechs are generally used as scout 'Mechs and anti-personnel units instead of frontline combat duty, but some are designated combat 'Mechs with relatively heavy armament. Their low production cost, high proliferation, and relatively good supply of spare parts meant that they saw widespread use throughout history in virtually any role.
Famous light scout 'Mechs include the Locust, Stinger, and Wasp, while the Commando, Jenner, and Panther are powerful combat units for their size. Clan technology provides their designs such as the Adder (Puma) with firepower equalling Inner Sphere 'Mechs twice their size.
Medium 'Mechs are the workhorse 'Mechs of most armies. Weighing between 40 and 55 tons they naturally fall somewhere in between the agile light 'Mechs and the powerfully armed heavy 'Mechs. While matching neither in their respective niche, medium 'Mechs tend to have the best combination between speed, armor, and payload which gives them unmatched versatility. The fastest medium 'Mechs often serve as command units among light 'Mechs with similar speed. Better armed than light 'Mechs, medium 'Mechs can often outmaneuver heavier opponents in combat and bring their weapons to bear with better effect to the point of being superior combatants in single combat, given time and suitable terrain.
Heavy 'Mechs are those designed for frontline combat duty, and weigh in between 60 and 75 tons. They are slightly less versatile and generally slower than medium 'Mechs, but tend to have much heavier armor and weapon payloads. Capable of delivering sustained heavy fire over long ranges while retaining adequate mobility, they are formidable and powerful foes. Some designs are adapted to special roles in combat which greatly improves the combat performance of their unit but makes them a poor choice in single combat situations.
Assault 'Mechs are the heaviest regular class of BattleMechs, weighing in between 80 and 100 tons. Some of these huge 'Mechs can mount up to 50 tons of weapons as well as very thick armor protection. They can project tremendous firepower, and perform best as the spearhead of frontal assaults or in defending entrenched positions. The trade-off is in speed and maneuverability, as assault 'Mechs are generally very slow. As such, they often require friendly units to protect them from being outmaneuvered. Assault 'Mechs are typically used as command units, heavy assault platforms, and in fire-support roles, but due to their prohibitive costs and limited production, they actually make up only a small fraction of all BattleMechs.
Since the late 28th century, designers had attempted to construct BattleMechs in excess of 100 tons. While most of these efforts were unsuccessful and even scorned (most famously Amaris' Folly), the Word of Blake was able to produce successful prototype "Omega" towards the end of the Jihad.
In the early 3120s, Colossal BattleMechs began appearing as an experimental technology. The Ares Colossal 'Mechs was manned by a crew of three (Pilot, Gunner, and Engineer) and tipped the scales at 135 tons. The known variants are called "Hades", "Hera", "Zeus", and "Poseidon".
 Industrial 'Mechs
IndustrialMechs (also known as WorkMechs, UtilityMechs or, where applicable, ICE 'Mechs), though far less glamorous than their war-faring counterparts, are very important in the everyday life of the BattleTech universe. There are AgroMechs, ForestryMechs and LoggerMechs, LoaderMechs, MiningMechs, and many other types for many different industries including even armed SecurityMechs. Many of these 'Mechs use an internal combustion engine (ICE), usually diesel, due to the high cost of fusion reactors.
Industrial 'Mechs have occasionally been modified for war when normal 'Mechs are out of reach (most often in the MechWarrior: Dark Age saga), although the modified WorkMech is usually far less capable than a BattleMech of the same tonnage. They tend to be equipped with relatively light armor, but can pack a deadly punch in close combat with varying array of industrial-grade tools including saws, drills and utility lasers.
 Additional Components
 BattleMech Listings
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