A BattleMech (Mech), in the science fiction of BattleTech, is a war machine about 10-12 meters in height, and 20 to 100 tonnes in weight. These vehicles are powered by fusion reactors and are capable of fighting underwater and in outer space.
BattleMechs use a muscle-like artificial fibre called myomer to allow the 'Mech to walk and move. Powerful gyroscopes provide stability, which the pilot controls with a neurohelmet that effectively links the 'Mech's computer into the pilot's sense of balance and nervous system. The movement of a 'Mech is controlled by joystick.
BattleMechs are armed with a frightening array of weaponry, including lasers, machine guns, autocannons, gauss rifles, flamers, particle projection cannons (PPCs), short, medium, and long range missiles, (interestingly, BattleTech missiles are far shorter ranged than their modern counterparts which was explained by guidance technology being lost over time, through the Succession Wars), and the 'Mech's own arms and legs. A single 'Mech can easily destroy a city. A BattleMech's only true rival is another 'Mech - artillery, aircraft, and tanks are nearly worthless against them without BattleMech support or a strong advantage in numbers.
The first BattleMech ever developed was the Mackie, a well-described 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.
The LAM had the ability to transform into a conventional aircraft and revert to BattleMech mode, enabling it to quickly traverse great distances in a short time. However its weight limit, real life legal conflicts with Harmony Gold (The LAMs, as well as several other 'Mechs, were based heavily off of 'Mecha designs from The Super Dimension Fortress Macross and other anime series) would end its official existence within the universe. The Wasp, Stinger and Phoenix Hawk were famous LAMs. These Land Air 'Mechs can be found in the original edition of Technical Readout: 3025, along with the other "lost" or "unseen" BattleMechs such as the Marauder, Crusader, Warhammer, and the non-LAM versions of the Stinger, Wasp, and Phoenix Hawk.
The Quad 'Mech, though much maligned, has experienced a bit of a renaissance in the years after 3060. With the rediscovery of more efficient weapons, internal structure, and armor, the Quad 'Mech's stability and ability to carry heavy weapons has much improved. However, the stigma associated with the general design still lingers, leaving the normal dual-legged BattleMech the vastly more common 'Mech. Notable Quad designs include the 55 tonne Scorpion, 80 ton Goliath, 70 ton Barghest, and 100 ton Sirocco
Certain 'Mechs have become iconic within the BattleTech Universe. The birdlike 75 tonne Timber Wolf/Mad Cat (pictured in the Legend of The Jade Phoenix novel cover above right) is popular both for its aesthetic quality and in-game performance. The Timber Wolf is a very popular subject for art, both in official BattleTech material and fan artwork. The Timber Wolf is known as the Mad Cat to the Inner Sphere armies because of its similarities to the MAD 'Marauder' (the low slung arms) and the CAT 'Catapult' (the reverse jointed legs and twin LRM 20 (long range missile) launchers on it shoulders. In the Btech universe itself, the Timber Wolf has become a symbol of the Clan invasion.
Primary characters in BattleTech stories often use customized 'Mechs. For example, Kai Allard-Liao pilots a unique Centurion medium BattleMech called "Yen-Lo-Wang" which features a slightly different weapons configuration than a standard centurion. Prince Victor Steiner-Davion uses a custom Dire Wolf/Daishi Assault 'Mech with more high-calibre weapons (the usual configuration sports multiple small and medium weight weapons). Jade Falcon hero Aidan Pryde pilots a custom jump-capable Timber Wolf. Gray Norton piloted a customized Rifleman fire support and anti aircraft 'Mech dubbed "Legend Killer", and although exactly what modifications were made to the chassis are unknown, they transformed the otherwise mediocre rifleman into a deadly area fighter. Finally, Natasha "The Black Widow" Kerensky piloted a customized Dire Wolf somewhat similar to Victor's.