Essay: BattleMech Technology

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This essay was written by MekTek/MWO Mercs/MWLL forum poster Pht and posted here by him.


An in-depth look at the various technologies and systems of a BattleMech and their operation in concert with the MechWarrior to animate a BattleMech.

Internal Composition[edit]

BattleMechs have a large amount of articulation (joints). The basic design approach is to mimic the skeletal structure of humans by using an endo-skeleton. This means that most BattleMech systems are mounted to the exterior of the internals ("bones") instead of being caged in a frame. This is somewhat similar to how a human skeleton supports muscles, organs, and the rest of the human body. It is the internal structure ("bones") that support the whole structure. A 'Mech's armor only looks like it could hold it together... 'Mech armor is actually quite thin and unable to support much weight.

The Internals[edit]

'Mechs normally have around sixteen to twenty five bones. The low number of bones compared to human structure is due to couple of reasons: some structures that encompass a dozen or more bones in a human - for example the ribcage - are a one piece structure in 'Mechs. In other areas, simplified components serve the function of several bones. The human foot is a very complex structure of bones, yet it is replaced effectively with simple shock pads. This structural streamlining results in 'Mechs generally being less articulated and flexible than a purely human bone structure would allow.

The exterior of the bones are configured to mount the assorted equipment 'Mechs carry. Struts extend outward from the bones to hold the armor shell. Attachment points for the myomer "muscles" and various electrical servo motors are built onto the bones. All of the internal structure (bones) are rigged for easy attachment of sensors and equipment.

Weapons frame attachments, however, are custom designed into the internals for each 'Mech. Sometimes a bone is built around a weapon which attaches directly to that bone, such as the Panther's PPC. Sometimes weapons are attached on an independent mount which "sits between" the weapon and the bone and is attached to both, such as the Shadowhawk-K's shoulder PPC mount. In fact, different weapon models (even of the same class, like two different models of medium lasers) require different mountings. For these reasons there is always some customization, design, and engineering work required to mount different types or classes of weapons or even different models of the same weapon class in any particular BattleMech. OmniMechs are much easier to configure for mounting weapons because OmniMechs are designed to be modular.

Standard Internals[edit]

Standard Internals are formed of multi-part structures with a core of ultra-light foamed aluminum, shrouded in directionally oriented stressed sheets of silicon carbide mono-filament fibers. The fiber layer is also rigged with structural sensors and data lines. This core is then clad with titanium-alloyed steel.

Endo-Steel Internals[edit]

Endo-Steel internal structures are of the same basic configuration as Standard Internals. The major difference is in materials. Endo-Steel structures are made of endomorphic steel.

Endo-Steel is much stronger than standard internal structure allowing endo-steel internals to be built with structurally thinner walls and no fiber wrap reinforcement around their core (they still have the sensor and data lines wired into them, though). Endo-steel has the same strength as thicker walled standard internals which results in a lighter structure that is bulkier.

The downside is that the thinner walls make endo-steel internals less stiff than same diameter of Standard Internals, which means that endo-steel bones must be made with larger cores. It is necessary to understand that stiffness and strength are not the same qualities. For example a thick cardboard panel is stiffer... less likely to buckle, than a thin sheet of metal, even though the metal is far stronger. Endo-Steel is stronger, but its thinner structures are far more likely to buckle, requiring a physically larger core to support the same amount of weight that standard internal structure can.

Due to its composition, endo-steel must be made in zero-g to avoid chemical segregation (think of oil and water) which would severely weaken the alloy and make it brittle. Endo-Steel's foamed aluminum core is also formed in zero-g, which promotes a more regular pore size, giving the core superior strength. Zero g production makes endo-steel more expensive, but allows the elimination of the fiber layer, meaning faster production than standard internal structure.


'Mech joints are generally referred to as actuators. The term "actuators" refers to a 'Mech's joints, associated myomers, and Motor Control Units. The joints themselves are usually ball type, like hips, or hinge type, like elbows. These are sealed joints which are normally filled with dry lubricants like graphite or hexagonal boron nitride. Each actuator has a degree of local motor control and feedback. These joints are moved by the myomers in a similar fashion to how human muscles motivate their attached structures. These actuators are too slow and too clumsy to provide the quick, fine movements necessary to maintain balance by themselves.

Motor Control Units[edit]

Each joint has a Motor Control Unit (MCU) that controls the joint by sending electrical power to the appropriate myomer bundles and monitoring feedback. For redundancy, the power controls for myomer strands are mounted at both ends. The MCUs manage the thousands of myomer fibers in each myomer bundle, contracting them on demand. MCUs can self-adjust a 'Mech's actuators at humanly undetectable levels without input from the MechWarrior. In fact, Clan actuators are advanced enough that they can adjust for a slight breeze, compensating by subtle shifts of the 'Mech to lean it into the wind.

The MCU's also monitor feedback from sensors wired into the actuator structures, which provides the positional information of the joint relative to the rest of the BattleMech to the MCUs. The MCU's then take this positional information along with all known programmed movements and pulses this information to the Diagnostic Interpretation computer (DI).

The DI computer then takes these inputs and cross-references them with data from the Battle Computer and the Gyro system and distributes it back to the MCU's in order to maintain the balance of the 'Mech. The entire group of MCUs together is known as the 'Mech Movement Sub-System (MMSS). The MMSS system receives data from the DI computer about the current tension, strength, position, and power usage level of all of the various myomers in the 'Mech, along with already mentioned balance data from the Gyro system. This data is used by the MMSS to to keep the 'Mech upright and stable and also to make any adjustments that the Battle Computer is requesting.

Lastly, when a BattleMech is shut down, the actuators lock into place, keeping the 'Mech upright (or however it was when it experienced shutdown).


Myomers are made up of microscopically thin polyacetylene tubes filled with a contracting substance. Each individual tube is extruded in microscopic forms and spun into a bundle (this bundle also contains sensors and data/control lines). The contractile filling - "acti-strandular fiber" - is produced by genetically engineered bacteria in vats. This acti-strandular precursor material is then strained out of the vats, and combined with specific polymer fillers. This combination is squirted into the polyacetylene tubes. The tubes are then electrified, which causes the acti-strandular precursor material to self arrange into complex nanoscale structures somewhat like the contractile protein filaments (myosin and actin) in natural muscle.

When enough electrical energy is applied to activate the myomer strand the fibers contract in a process virtually identical to the contraction of protein filaments in natural muscles, excepting that the power is applied in a direct electrical form instead of a chemical one. This contraction is an all or nothing process - the level of force generated by myomer bundles is controlled by the number of myomer tubes contracted, rather than the amount of electrical current applied to the myomers. Because myomers are far more powerful for their weight than human muscle and can be built on larger scales, they make BattleMech scale movement possible.

Myomers are not merely 'Mech scale plastic muscles. Rather, they are very powerful electrical motors. For reference, the myomer bundles in a 'Mechs fingers are multi-kilowatt motors. The leg myomers are far more powerful. The downside of myomers is that they aren't efficient electrical motors due to high internal electrical resistance. Myomers are roughly as wasteful of energy as natural muscle or internal combustion engines... much of the energy required to activate them is simply wasted into heat. Myomers can actually generate enough waste heat to cook themselves, and so the Myomer bundles are laced with a network of flexible tubing which carries coolant fluids to and from the BattleMech's Heat Sink system to handle this waste heat.

As an important side note, it is a misconception that lightning or PPC fire (which actually is nothing like lightning) can spasm a 'Mech and cause it to rip its myomers apart. 'Mech structure and armor provides a very low resistance conduit to earth ground and as such will protect the myomers from the electrical energy. The WOB 'Mech tasers work because they provide a much closer ground (lower resistance path) to the feed channel of the taser - whatever is in between the contacts (or is electrically connected to the area between the contacts) of the mech-taser is subjected to massive amperage (it's amps that do the damage, not volts).

Triple Strength Myomers[edit]

"Triple strength myomers" are very much like normal Myomers but they operate more efficiently in a specific range of higher heat because of a simple endothermic chemical reaction within the myomers.


The gyroscope is the device that provides the swift, fine changes in force necessary to keep a BattleMech upright. Even the best 'Mech actuators are too slow and imprecise to apply the force needed to keep a 'Mech upright. Without an active gyroscope a BattleMech can not move - it will fall over and will not be able to get up.

A 'Mech's gyro system consists of a balance-sensing mechanism and a force-generating mechanism.


A BattleMech's internal balance sensing component usually encompasses a small computer in the cockpit incorporating balance-sensors. The sensors operate in differing manners - some use laser ring gyroscopes, or harmonic vibration gyroscopes, or even mercury bead setups. These sensors can also act as a 'Mech's inertial navigation system.

While an effective system for keeping the 'Mech upright, these balance sensing systems can be fooled fairly easily. High speed impacts, sudden changes in altitude, and especially the loss of one or more frames of reference (such as falling in mid air - the loss of gravity as a frame of reference).

Also, 'Mechs are not good at determining when they should be off-balance, which is surprisingly useful in combat. Leaning away from an attack, or leaning into a physical attack, and a myriad of other tactics are essential on the battlefield.

While it is not a part of the dedicated balance sensing system proper, the Diagnostic Interpretation computer, via its vast network of status sensors, can compensate for incoming fire by having the 'Mech "lean into" it... the Diagnostic Interpretation computer also compensates for the recoil of the BattleMech's autocannons and other recoil generating weapons, in both instances in order to try and maintain the 'Mech's balance. However, it is the MechWarrior's sense of balance, as translated by the Neurohelmet, that handles what the balance sensors and Diagnostic Interpretation computer cannot cope with or predict for.


Located in the torso is a multi-ton assembly of reaction wheels. Reaction wheels are spinning rings.

The gyro is made of two major assemblies. The first is the housing, made of a carbon nanotube reinforced polymer inner shell and a light ceramic outer layer. The internally mounted reaction rings are made of carbon nanotube reinforced graphite.

When a 'Mech loses its balance, the gyro mechanism will stop one of the (very) fast-spinning wheels and impart a reaction in the direction the wheel was spinning, or it will speed up a ring and as a reaction will impart a shove in the opposite direction of the push on the wheel.

Gyroscope configurations vary from manufacturer to manufacturer. Most gyros have at least three reaction wheels set at 90 degrees to each other. Some gyroscopes mount the reaction rings in a free-spinning sphere in order to avoid the reaction wheels inhibiting a BattleMech's movement with unwanted gyroscopic effects. This design requires locking the outside sphere in order to use the reaction wheels. Some gyroscopes use six reaction wheels set up in three counter-rotating pairs, also to cancel gyroscopic problems. None of these designs is necessarily more capable than the others.

The Neurohelmet[edit]

The neurohelmet's main job is to enable the MechWarrior to control the balance of the BattleMech. The MechWarrior uses the neurohelmet to tell a 'Mech when and in what direction it should be off balance, and also to help the 'Mech regain its bearings when its balance systems cannot compensate enough for the 'Mech's condition. The neurohelmet is also used as a part of the security system of a 'Mech. First, a pilot must match the neurohelmet tuning profile, or they most likely will not be able to plot the 'Mech. Second, if a pilot does pass the 'Mech's security tests, the 'Mech's computers can use the neurohelmet to scramble a would-be thief’s brains.

Putting Data In[edit]

The massive neurohelmets of the Succession Wars, which sat on the shoulders and inhibited the MechWarriors ability to turn their head, compressed a 360-degree view from external cameras and sensors into a 160-degree HUD display in the helmet with the different firing arcs delineated and having their own reticules for weapons visible in those firing arcs. More capable and more modern neurohelmets, such as Clan versions, are smaller and lighter, having large visors and while not requiring the old style HUD display in the helmet. Modern (post 3050) neurohelmets that do not have an internal HUD can be modified to display one.

Neurohelmets also have audio systems which generate audible cues, alerting a MechWarrior to threats. Modern Neurohelmets generate these cues in three dimensions, allowing the MechWarrior to quickly locate a threat.

The first Star League did develop some very capable neurohelmets, the best of which were massive units used in aerospace fighters. Advanced neurohelmets are capable of providing sensor and balance information from the 'Mech's sensors to the MechWarrior. This "direct neural virtual reality" is very weak, because even the best neurohelmets cannot put enough signal power into the brain to overwhelm the natural biological sensory signals without cooking brain cells. This input limitation is due to the wireless method that neurohelmets use to send information into the user's brain cells.

Getting Data Out[edit]

Getting information out is far easier, being a passive process. The achilles heel of getting complex information out of a brain via a neurohelmet is that of the complexity of the human brain, which makes it a hard thing to read. Because of this, neurohelmets "watch" a few specific centers of the brain which are easily translated into commands. The end result of this is an interface that makes it possible for MechWarriors to communicate their basic intentions to their 'Mech more quickly and clearly than speech controls would allow for. This overall process is not quick or smooth, but it does work. For instance, when charging at another 'Mech, the pilot would use the neurohelmet to, at a very visceral low level, command the 'Mech to throw itself off balance towards the targeted 'Mech.

Neurohelmets often include the ability to change communications channels by clenching and unclenching the jaw, or opening the mouth fully.

Fine Tuning[edit]

Because of the plasticity of the human brain in order to "watch" and transmit to the appropriate brain centers most neurohelmets have to be fine-tuned to each MechWarrior.

The Outside Limits[edit]

While the neurohelmet can help translate the MechWarrior's basic intentions to the BattleMech and give a small amount of feedback to the MechWarrior, they aren't capable of real-time "mind reading" that would be necessary in order to directly control a BattleMech's movements, nor can they input enough data to a MechWarrior to replace the cockpit information systems.

The first Star League could not make helmets capable of this and neither can the Clans.


Standard Armor[edit]

BattleMech armor is formed in tightly bonded multiple layers, just two of which can properly be called armor.

The outer layer is an extremely strong, extremely hard layer of steel. It fragments projectiles. It ablates and conducts heat to provide protection from energy attacks. The crystalline structure of this steel is carefully aligned and radiation treated for maximum hardness and strength. Because of its phenomenal strength and hardness, the outer layer suffers the trade off of being quite brittle. It is so brittle that the second layer of armor - a ceramic, cubic boron nitride - has to act as a backstop for fragments of the outer layer, molten outer armor, and even outer armor converted into plasma by heavy attack.

The second layer, cubic boron nitride - a very hard layer in its own right - is processed to avoid porosity and includes a micro fiber web of man made diamond mono-filament fibers, along with sensors and data/control lines. This weave imparts a little bit of flexibility for this second layer that acts as a backstop to the outer layer. This layer also stops High Explosive Armor Piercing (HEAP) rounds and fast neutrons.

The next layer is a titanium alloy honeycomb. This layer provides no armor protection - it is instead used to support the outer armor layers. The first and second armor layers are millimeter- and centimeter-level thin in order to cover the massive surface area of a 'Mech with a proportionately small quantity of armor. This makes the armor very thin for its length and width. As such, the titanium honeycomb holds the armor in place and keeps it from flexing so much that it shatters like a pane of glass. The comment about strength and stiffness of endo-steel applies here. This tendency to shatter due to its extreme hardness is one of the contributing factors in why BattleMechs lose armor when they fall, suffer physical attacks from other BattleMechs, or collide with structures - flex any armor panel too far and it shatters like a piece of glass pushed beyond its limits.

The various plates of armor are mounted onto struts that extend outwards from the internal structure of the BattleMech. These mountings and the armor plates are configured so that the armor plates overlap each other, leaving only relatively small gaps, just large enough for atmosphere or liquids to traverse.

The last layer is a polymer sealant, which seals off the gaps between the individual armor plates, making a BattleMech air tight and water proof. The polymers used usually have some self-sealing capability (just enough to handle small punctures and gaps) and are heat resistant in order to survive the high internal temperatures of a BattleMech in combat.

There are other types of armor on 'Mechs. Actuator armoring can be from a wide range of protective materials - ballistic or ablative fabrics to articulated plates of standard armor. Cockpit view screens use a large selection of transparent armors in combination, anything from ferroglass to alternating diamond and polymer sheets.

Ferro-fibrous Armor[edit]

Ferro-fibrous armor adds a weave of diamond fibers to the outer steel layer itself. This is quite the trick because steel is a combination of iron and carbon, would normally mean the diamond weave, which is pure carbon, would dissolve into the iron component of the steel. The techniques used to keep the diamond from melting into the iron component results in bulkier but lighter armor. Originally researched and made in the first Star League era, the technology became "lostech" in the inner sphere for a long time. Clan ferro-fibrous is denser and is more capable of being shaped, allowing maximization of internal space in a 'Mech. Inner Sphere ferro-fibrous doesn't shape well into anything other than flat plates due to its bulk.

There are various types of ferro-fibrous armor in the Inner Sphere providing varying levels of protection by mass and weight. This is achieved by changing the amount of diamond fibers in the armor.

Light ferro-fibrous armor has fewer fibers. It is less bulky but also less protective by weight. Heavy ferro-fibrous armor has more fiber and has better protective capability by weight than even Clan armor, but the downside is massive bulk.

Stealth Armor[edit]

Stealth armor is a Capellan development that is actually a variation on standard ferro-fibrous armor. It is an attempt to duplicate the functions of the first Star League's Null Signature System. Stealth armor, though, has to use a separate guardian ECM suite in order to attain its capabilities. Stealth armor incorporates a number of emission suppressing materials that are fairly heavy, which makes it roughly as protective as standard armor by weight. The suppressing effect is not attained through materials alone - the BattleMech's structure has to be set up to use stealth armor - heat sinks are rerouted so they can be suppressed, corners and surfaces molded to control radar reflections, and internal baffles are used to mask the massive magnetic field of the fusion engine itself.

Fusion Engines[edit]

Fusion reactors generate huge quantities of electrical power by fusing light elements like hydrogen into heavier elements like helium. Nuclear fission, on the other hand, splits heavy elements like uranium into lighter materials.

The usual fuel used in modern fusion engines is normal hydrogen, the protium isotope to be specific. Historically other fuels were used in early fusion reactors. Anything from heavier hydrogen isotopes like deuterium and tritium, to the helium-3 isotope and even lithium. These heavier isotopes are easier to use, but the fusion engines that operated on them generated more nuclear waste than the modern fusion engines.

In modern fusion reactors, the normal hydrogen used for fuel is extracted from any number of sources - particularly water. Because of this is most military fusion engines include an electrolysis unit to extract hydrogen from water.

In the early days some BattleMech designers experimented with using fusion engines that produced more power than a particular chassis needed. The idea was that the extra power produced would provide some nebulous benefits in combat. However, this turned out to not only be false, but the oversized engines actuall would generate too much heat and would either cook off explosive ammo stored in the BattleMech; or the engine safeties would cut in and automatically shut down the engine. A BattleMech can only use so much power... trying to force it to use more simply does not work.

Containment and Power Generation[edit]

The fusion engine utilizes a super hot (tens of millions of degrees Celsius) ball of hydrogen plasma which converts into helium to create energy. In order to keep the plasma ball from melting the engine it is contained within a magnetic field. This is possible because plasma is electrically charged and thus it can be positioned and shaped by magnetic fields. There are magnetic fields inside the plasma ball and fields generated outside the plasma. In fact, the plasma never (normally) touches the walls of the engine. The reactor chamber is kept as a vacuum for heat insulation. Also, because punctured fusion engines are ruined by contact with superheated oxygen (this causes almost instantaneous oxidization - "rust") fusion engine safety settings will normally shut down the fusion when the engine's external shielding suffers too much damage.

Power is extracted in two ways - the first is called "magnetohydrodynamics" or MHD. The shorter and mostly correct description of this process is that the plasma is like a dynamo, generating electrical currents in conductor loops that wrap around the reactor. MHD directly converts heat from the fuel into electricity. By operating at extreme temperatures MHD can exceed 90 percent efficiency in turning heat into electricity.

The second way of generating power is purely secondary and is called regenerative cooling. Regenerative cooling uses waste heat to generate power. Usually this is done with a closed-cycle gas or steam turbine. In a small way this is a part of the 'Mechs cooling system, even though this is not a part of the heat sink system proper - these are the "free" heatsinks in the engine. While the regenerative cooling machinery is very different from purpose built heat sinks, it still benefits from the materials and technology advances that have made "double strength" heat sinks possible. The regenerative cooling system adds negligible volume to the engine, due to its using the existing plumbing of the engine's cooling system. It would be quite useful if all the waste heat from an engine could be soaked up by these so-called "integral heat sinks," but practical limitations mean only so much energy can be extracted from this lower-quality source. Bigger engines make more waste heat and can have larger regenerative cooling systems, but most 'Mechs will use some conventional heat sinks placed elsewhere to handle the excess.

It is important to note that excessive heat from combat or other conditions can cause the magnetic fields to be disrupted. If this happens there is the potential for an uncontrolled fusion reaction, which could irradiate the inside of the BattleMech and expose the MechWarrior to lethal levels of radiation.

Shielding and Fusion Engine Types[edit]

All fusion reactions generate radiation. Fusion reactors irradiate their interiors, which causes problems when the reactor must be serviced or decommissioned. Also, Because of this radiation shielding is the largest portion of a 'Mech scale fusion engine's mass.

Standard fusion engines use a very dense ceramic for shielding, usually tungsten carbide reinforced with short boron ceramic fibers mixed into the carbide. This shielding is actually thick enough to survive battle damage and act as a heat sink (thermal mass) that can disperse the heat from the plasma should the magnetic containment fields fail and allow the plasma ball to expand and touch the walls.

Extra-light (XL) engines reduce the mass of the tungsten carbide reactor walls but reinforces them with an oriented crystalline plastic that creates a bulkier but lighter engine. Making large blocks of this shielding is very hard for engine manufacturers and the scrap rate is massive which accounts for some of the high price of XL engines.

So-called "light engines" use layered shielding materials and secondary magnetic screens. They are not quite as light as XL engines but they are less bulky.

Engine Cooling Systems[edit]

Fusion engines also have their own integral cooling system outside of the regenerative cooling system which is separate from the rest of the heat sink network. Liquid nitrogen jackets are used over key components, which allows minimal engine operations without using the external heat sink systems. Any more use of the engine requires the larger cooling capacity of the main heat sink and regenerative systems.

Fusion engine explosions[edit]

This is an urban legend that will not die ... fusion engines going critical and exploding as mini-nukes.

The magnetic fields which contain the plasma also protect the plasma from the frigid (relative to the temperature of the plasma) reactor chamber walls. The fusion reactions in a BattleMech fusion reactor only occur in a very narrow band of temperature and pressure conditions. The hotter and the higher the pressure, the faster the reactions occur.

When heat is added to a gas, it expands. If it can't expand, its pressure goes up. Thus when the reactions spike a bit the plasma gets hotter and in turn it tries to expand. However, the magnetic fields aren't rigid so they will expand a little a bit, allowing the plasma ball to expand, which, in turn, lowers the pressure in the plasma - which cools the plasma and allows it to collapse to its normal size. There is a little bit of extra room in the reactor chamber for just this reason.

There are, however, other ways the reaction can cool down. If the magnetic fields don't do their job, the plasma ball can actually touch the frigid walls of the core which results in the plasma ball "blinking out." This barely even scuffs the walls of the reactor. When the plasma ball contacts with the frigid walls of the fusion reactor the fusion reactions in the plasma stop almost instantly because there is no stored thermal mass in the plasma ball. All of the heat in the plasma comes from active reactions. The multi-ton reactor walls (comparative to the plasma ball) have so much thermal mass that they can soak up the heat of the reaction and barely heat up. The plasma ball does not normally have enough thermal energy to do more than add a little heat to the walls of the engine around it.

Fusion reactors do on very rare occasions die in a spectacular manner, but the majority of those times isn't due to an exploding reactor.

What normally happens is that the reactor core is breached allowing a large quantity of relatively cold air into the vacuum of the reactor chamber which puts out the fusion reaction instantly... but in so doing, the intruding air in the reactor chamber soaks up all the heat and comes blasting back out in a white-hot blinding gout of flame. Considering that it takes massive damage to breach a reactor core so quickly that the safety fields can't drop down before something intrudes into the chamber... the visual end effect is that the 'Mech has very nearly been blasted in half, followed very quickly by a blinding fireball. This is a spectacular way to decommission a fusion reactor - a rampaging super-hot oxygen flash fire - but it is not a nuclear blast.

In the last instance it will happen that a MechWarrior will figure out that they can overcharge the engine, causing the plasma ball to heat up to an amazingly high temperature - far beyond their normal operating range - and than kill the magnetic field quickly, causing the extremely overheated plasma to hit the reactor walls which causes the reactor lining to explosively evaporate. The result of this is that the reactor is over pressurized, which causes a respectable explosion - but again, not a nuclear explosion.

Cooling Systems[edit]

Heat Effects[edit]

BattleMechs are sealed and insulated vehicles, allowing them to fight under nearly any conditions. This prevents heat from venting off and 'Mechs have a lot of heat to shunt from the continuous megawatts of power they consume, not to mention heat from weapons fire and the environment. Excessive heat can impair or even damage a BattleMech's computers, electronics, and myomers, causing the 'Mech to move sluggishly and also to be inaccurate with its weapons.

High heat levels can be dangerous to the safety of the MechWarrior, causing heat stroke. Excess heat can also cause any stored explosive ammunition to cook off explosively - usually a catastrophic event for the 'Mech and its MechWarrior.

Heat Sinks[edit]

There is quite a bit of confusion about what BattleMech heat sinks really are. "Heat sink" is actually the wrong name. 'Mech "heat sinks" are actually heat pumps. However, the rest of this article will continue to use the term "heat sinks" instead of "heat pumps."

Heat sources[edit]

The fusion engine generates heat waste heat, in spite of converting most of the heat into energy. The balancing act of keeping a fusion reaction going often results in more fusion reactions being produced than needed for current energy demands. These extra reactions create waste heat, since they aren't converted into electricity. Energy weapons are inefficient at converting electricity into laser or particle beams, ballistic weapons create heat in their bores and barrels, and jump jets create a lot of waste heat. Lastly, myomers generate a large volume of comparatively lower temperature waste heat. Incidentally, myomers impose one of the primary limitations on the temperature a BattleMech can operate at, because as the myomers heat up, they become more resistive, less efficient, and less predictable at the same time. The acti-strandular materials in Myomers do not respond well to high temperatures. If Myomers become too hot, they will actually cook themselves, which results in the black smoke seen rising from extremely overheated BattleMechs in combat.

Collecting Heat[edit]

The engine and weapons have cooling jackets hooked to tubes which are networked into their frames. These tubes connect to the heat sink network. Myomer bundles have coolant lines laced through them in a manner not unlike a vascular system. All of these coolant lines run into collection systems that connect to the heat pumps and radiators that dump the heat.

Coolant fluids differ between depending on the manufacturer of the heat sink. Oils, chlorofluorocarbons, water-based solutions, liquid nitrogen, gaseous nitrogen, gaseous helium and other formulations are used. There are no 'Mechs using molten metals like the Tharkad City fusion engine - that would simply be too hazardous in combat. This coolant solution is then circulated through the 'Mech by a wide variety of pumps. Most modern heat sinks no longer use mechanical pumps. Instead they use myomer wrapped flexible tubing that pulses (peristaltic) in order to circulate coolants. This setup is more tolerant of damage than centrally located mechanical pumps. In addition, the whole system of coolant lines employs many computer-controlled cut off valves to stop catastrophic loss of coolant due to damage, and computer controls can also reroute coolant around damaged systems.

Heat Pumps[edit]

Heat pumps collect and condense heat until it can be easily shunted out through the radiators, even into environments hotter than the 'Mech. Many different heat pumps are used by different manufacturers. There are vapor-compression systems, sonic cooling systems, magneto-caloric systems, expansion compression systems, heat expansion systems, and others.

Dumping Heat[edit]

At one end of the heat sink assembly is the radiator. BattleMech radiators aren't very different from car or refrigerator radiators. Radiators consist of finned tubing carrying hot coolant that is either air or water cooled. They are usually made of graphite which is five times more thermally conductive than copper. These radiators are always hidden under armored grills. Some Periphery nations have used copper for heat sink radiators which actually works fairly well because copper allows for thinner construction, meaning more surface area to radiate heat from. The net performance drop from using copper radiators is fairly negligible.

The wonder plastics of the first Star League had a big hand in enhancing radiators. While these semi-crystalline polymers don't quite have graphite's thermal conductivity, they are dramatically lighter, allowing larger radiators for the same mass as standard heat sinks. This what allows for "double strength" heat sinks. Unlike most recovered lostech in the Inner Sphere these double strength heat sinks did not originate from the helm memory core. The New Avalon Institute of Science was experimenting with this tech before the helm core was found. The Clans never lost this technology and they even improved on it by making the material more crystalline, which makes for a more thermally conductive and compact but more brittle radiator. The required reinforcements keep the Clan double strength heat sinks at about the same mass as Inner Sphere versions.

Radiators are why "heat sinks" actually have to use heat pumps. The laws of thermodynamics state that heat flows from hot to cold. Thus, if your 'Mech is operating in a very hot environment, the radiators would actually send heat into your 'Mech's coolant system.

Jump Jets[edit]

Jump jets work by ingesting atmosphere via a system of turbo compressors to be used as reaction mass in reaction chambers. The system hits the compressed reaction mass with electron beams powered by the magnetohydrodynamic tap from the fusion engine, which converts the compressed reaction mass into an explosion of plasma. This superheated plasma is than channeled through a magnetically sealed venturi baffle, resulting in a controlled and concentrated flow out of the jump jet exhaust port. BattleMech jump jets don't add plasma vented from the fusion engine - only aerofighters do this. Because jump jets work with plasma, their reaction chambers closely resemble fusion reactors; down to the magnetic containment fields.

Jump jets can only be run for so long due to a couple of reasons; the first being that they can not survive their operating temperatures for an extended amount of time, and the second is that they normally ingest oxygen rich atmosphere for reaction mass - the super heated oxygen would destroy the assembly if it were continuously used. BattleMechs normally carry a small supply of reaction mass - usually hydrogen, water, or mercury - in order to operate where there is no atmosphere.

Why underwater jump jets will not work. Firing a jump jet filled with incompressible water generates enough pressure to rupture even the toughened jump jet casings. Jump jets can not use stored reaction mass under water either - the jets will not work with water plugging their nozzles.

Major Computer Systems & Sensors[edit]

Battle Computer/Targeting & Tracking system[edit]

The Battle Computer (BC), located in the cockpit, coordinates and monitors the overall movement and weapons fire. It is the BC that makes sure that the MechWarrior's commands have priority. The BC makes certain that weapons are pointed towards what the MechWarrior is indicating, even if that requires overriding other systems and warnings and putting an arm through the wall of a nearby building. It is the BC that does the computing for "Targeting and Tracking."

The BC is the "gateway" that filters the data from the DI computer, converting it to information that is useful for the MechWarrior so the MechWarrior does not need to interpret it. It also coordinates all of the weapons Targeting and Tracking (T&T) systems, feeding them and the MechWarrior data on internal checks that the DI computer has run. The BC also controls the Target Interlock Circuits (TIC) of the 'Mech.

BattleMech targeting and tracking systems consist more than just the BC - the system is a network of sophisticated sensors, sub-computers, and programming. Thermal imaging, light amplification, radar, laser tracking, uv tracking, and magnetic anomaly sensors are generally used as primary sensors, supplemented by seismic sensors, motion detectors, chemical analyzers, microwave, tracking, and many others, depending on what equipment a 'Mech mounts. However, MechWarriors are not overwhelmed with raw data... The BC compresses, interprets, and prioritizes the information. When the MechWarrior gets the info, it is displayed on the cockpit displays or on the neurohelmet heads-up display (HUD) in with all the various selected sensor information synthesized into a single viewing mode, with important things tagged by the computer with graphic icons onscreen.

Sensor readouts can either overlap a target or reveal an area. For example, thermal sensors display a green (cold) to white (hot) image of the battlefield. The MechWarrior can opt to display other 'Mechs with thermal imaging and leave the battlefield in true colors. Extra sensor readings can be added or subtracted from the displays as the MechWarrior wishes. Normally the battle computer will synthesize all of the various sensor inputs onto the display, although in a simplified form.

Identify Friend/Foe (IFF) is a key ability of the T&T system. It eases the burden of identifying targets for MechWarriors in battle conditions, especially in poor visibility. Friendly and enemy 'Mechs are tagged with differing graphic tokens. IFF broadcast beacons are used by the BattleMech's targeting and tracking system to avoid accidental missile fire at a friendly 'Mech, though the system can be manually overridden.

BattleMech sensory processors and programming stand out for their ability to recognize other units and classify them by type and as friend or foe. Virtually all T&T suites can tell what type of unit is being detected, and can even make educated guesses at what variant that unit is. The system is surprisingly intuitive and at times it will present an interesting "guess." For example, the famous Inner Sphere naming of the Clan Timber Wolf OmniMech. The first Inner Sphere BattleMech to encounter one saw it as a cross between two designs it already knew - the Marauder and Catapult designs, thus the name "Mad Cat" was born.

BattleMechs can also share some sensor data. Specialized C3, C3i, and other hardware takes this to new heights, but all BattleMechs can at the least handle basic sensory data from friendly 'Mechs in order to pinpoint enemy positions, or share more detailed information. This is usually done with a separate communications channel, and can be difficult to maintain during battle.

In a pinch, the BC can stand in for the DI computer, but this reduces the amount of information gathered and degrades the overall performance of the BattleMech to about 60% of normal. This translates to 60% of the sensors giving "old" or inaccurate data and weapons systems being unable to track and accurately hit whatever the pilot is indicating.

Diagnostic Interpretation Computer[edit]

The DI computer is a network of distributed computers that monitor and coordinate the most of the internal functions and components of a BattleMech. As noted earlier, the internal structure, armor, actuators, myomers, and other components are wired with sensors and data/control lines. The DI computer uses this network to monitor the health and status of all of the connected components. In so doing, the DI tracks the 'Mechs state of readiness and feeds this to the Battle Damage Assessment computer (BDA) which in turn translates and displays this information on readouts for the MechWarrior. All other interpretive computers and all sensors are subordinated to the DI.

However, the DI handles more than simple status assessment. The DI also uses its network of lines as a back-up data feed to other components. For example, if a BattleMech's hand is dangling by a piece of armor, the DI can determine the status of the finger actuators through data lines in the armor. While the BattleMech would not be able to do much with the hand, it would be able to communicate with it. This capability allows BattleMechs to function even as they suffer from massive internal damage. The DI computer itself is quite redundant and damage resistant. The DI locates some key hardware in the cockpit, but the rest of its hardware is scattered throughout the BattleMech nearer to systems the DI hardware controls. These sub-processing units are setup very redundantly and are capable of managing systems for other damaged DI sub-systems. For example, DI computers located in the engine might wind up handling leg actuators after a penetrating shot lobotomizes the DI processors in the legs. It is the DI, via sensors attached to the ammo bins in a 'Mech, that activates the automated pilot ejection system in the case of an ammunition explosion.

The DI can stand in for a damaged Battle Computer, but the 'Mech operates at about 70% of its normal effectiveness.


The DI computer manages all the systems in a BattleMech. All components have their own controlling sub-computers which are brought together by the DI system. The DI, for example, sends commands to actuator MCUs in order to promote smooth limb motions. Each weapon system sub-computer will send its state of readiness or malfunction to the DI computer. More advanced DI computers will indicate to the MechWarrior what the cause of the problem is and try to fix the malfunction, all with no input from the MechWarrior. The DI also keeps the 'Mech from damaging itself. For instance, it will cut back on systems that generate heat when the 'Mech suffers from heat sink damage or is in a very hot environment. It is also capable of overriding the "common sense" of the component level systems. When the MechWarrior demands it, the DI will run the engine hot even if the engine control computer is trying to keep the engine cool. When a MechWarrior pushes the throttle forward, it is the DI controls the engine power, the gyro, and coordinates actuators. When a BattleMech takes damage, the DI is what reconfigures leaking heat sinks, bypasses severed myomers and tries to re-route power to disconnected weapons.


The DI also handles 'Mech security. Normal security routines involve the MechWarrior thinking his way through several commands while wearing the neurohelmet, along with voice recognition, codes input from the keyboard, or even 'Mech gesture "code keys." The DI computer also decides whether or not to scramble a would-be thief's brain with the neurohelmet. Clanners normally do not pay attention to this aspect of security, since, according to them, "there are no thieves in Clan society."

Systems status sensors[edit]

BattleMechs have an extensive network of status sensors that send information about various systems up to higher-level systems. There are jump jet ready indicators, ammo low/critical indicators, heat build-up, proximity warning, incoming transmission warnings, IFF engaged/disabled, limb overstress indicators, engine shielding sensors that track the status of the fusion reactor core and magnetic shielding, armor sensors, and various others.

The internal structures, myomer, armor, and other systems are laced with sensors and data lines connected to the various computer systems of the BattleMechs . Sensors will transfer their information across any part of the 'Mechs internal data network that is not damaged. This sensor information is usually sent via multiple routes, in case one route is damaged. 'Mech sensors are very redundant in this right.

All of the sensor, MechWarrior condition, and communications data are recorded into capable "black box" computers that can survive virtually any kind of damage... from an ammo explosion to a failed orbital drop. This is the so-called "BattleROM" box. It uses read only rom chips, which are very hard to modify in the field. Because of this, battleROM data is used for court martials and other such sensitive proceedings. BattleROM boxes usually record the last 200 active hours of a BattleMech.


BattleMechs are ground vehicles, yet their cockpits are more similar to those of aerospace fighters than other types of units. Inner Sphere cockpits normally include features tailored towards long engagements. Clan cockpits, however, do not usually incorporate these features, and are smaller and narrower than Inner Sphere cockpits, reflecting the clan ethos of efficiency and short, brutal campaigns.

Life Support[edit]

BattleMech cockpits are sealed, pressurized, and equipped with life support systems. There is a lot of gear that must be built into a cockpit, and this limits life support systems. BattleMech life support systems are not capable of unlimited air and water recycling - there simply isn't enough weight and space available to build systems that can do so. 'Mechs can operate for a few hours to several days in vacuum depending on the design. In environments with oxygen or water, the life support system can make oxygen as long as the fusion engine is running. In order to achieve this the life support system pulls in oxygen through filters or uses an electrolysis system to separate the oxygen out of water. If the 'Mech is shut down, most life support units have ports for conventional personal battery packs that can keep them running for hours.

The filtration systems in common use around the time of the late Succession Wars, however, are not capable of filtering out the chemical weapons used by the Word of Blake. Many 'Mechs still use such filtration systems.

Climate control systems are of utmost importance in BattleMechs. Although it is very rare, 'Mech cockpits can get too cold for the pilot. There are fusion-powered heaters that kick in to bring the temperature up to levels that are more comfortable. The vast majority of time a 'Mech cockpit bears more resemblance to a sauna... overheating is a serious issue. BattleMech cockpits have robust cooling systems, but unfortunately, 'Mechs can and do run hot enough to heat the cockpit up to unsafe levels. The cockpit can get so hot that if the life support systems aren't functioning the pilot can be killed by the heat, although modern life support systems are normally capable of preventing heat stroke. Technological advances have provided old Star League style pilot suits that will keep a MechWarrior cooler, but unfortunately these advanced suits are not common. This is why MechWarriors pilot their 'Mechs wearing uniforms more appropriate for a beach than the cockpit of an armored combat vehicle.

Amenities & Storage[edit]

Most BattleMech cockpits have storage lockers for rations, field gear, medical and other supplies. They will also have a sizable amount of water for the MechWarrior's use in a cooled or insulated container. Larger cockpits are sometimes well equipped with amenities, such as small microwave ovens, refrigerated food storage, and even sleeping and sanitary amenities for extended engagements in the field. Most command chairs have a small storage locker for emergency supplies in the case of command seat emergency ejection.

Most 'Mechs have a foldout passenger seat; some 'Mechs even include a full ejection seat for passengers and give them access to some controls, such as communications systems. Most Inner Sphere BattleMechs have one more seat in the cockpit - a foldout toilet. Most 'Mechs dispose of the waste via a high-powered electrical arc or microwaves, and will capture water produced by incineration for flushing the waste out... the amount of endurance a 'Mech has in the field can be limited by how much toilet paper a MechWarrior chooses to carry. Spartan Clan cockpits rarely have toilets.

In terms of ergonomics and layout, there is no such thing as a truly "standard" cockpit. Layouts vary between manufacturers. That said, there is enough similarity between cockpits that a MechWarrior can usually acclimate to the controls of a new BattleMech in a short amount of time.


Configurability or the lack thereof is a source of much debate. Inner Sphere 'Mech designs tend to go through cycles of either being setup with multi-function displays and programmable switches or with fixed displays with single function switches. Fixed function setups are somewhat more damage tolerant in that one destroyed control won't take out an entire suite of functions. Proponents of fixed control setups also say they allow for quicker operation, because controls never change. Ironically, adjustable control setup proponents also claim reflex advantages. They say this because a MechWarrior can customize his controls and displays to suit his preferences, which supposedly allows for quicker operation. In reality, the difference in speed is not much, if it even exists. This is mostly because MechWarriors have so much to learn just to qualify to pilot a 'Mech that most pilots don't alter their control setups. In fact, standard training 'Mech layouts are very similar between the Clans and the Inner Sphere. Thus, virtually all 'Mech cockpits and default configurations are similar. OmniMechs, though, practically require configurable and customizable controls.

Displays & Audibles[edit]

While 'Mechs have dashboard and HUD displays, neurohelmets have often used an internal HUD. The average MechWarrior will customize the way the data is presented to him in his cockpit. These preferences can be saved on the battleROM chips that MechWarriors usually carry, in order to transfer settings between 'Mechs. Audible cues and verbal commands are also used to control a BattleMech. BattleMechs have generally had excellent speech recognition systems that are capable of understanding commands from the MechWarrior when he is screaming in combat, wounded, or otherwise engaged. Most Inner Sphere MechWarriors use the speech recognition only for 'Mech security. Audio cues are usually handled via speakers mounted in the neurohelmet that generate either warning tones, or 3-D positional alarms to help a MechWarrior quickly locate threats.


The actual controls for a BattleMech are fairly simple, regardless of the complexity of the average BattleMech. This is not because the of the ignorant idea that the MechWarrior links directly with the BattleMech through the neurohelmet. BattleMech controls are simple because the 'Mech handles the majority of the mundane details of operation. 'Mechs usually have two or three main control sticks.

Again, not all BattleMechs will have the exact same setup, but most 'Mechs utilize control setups fairly similar to each other, much like how most Ground car controls (steering wheel, brakes, accelerator, shift control, light and wiper controls, etc.) are similar.

Provided for reference, the cockpit control setup of a T-IT-N10M Grand Titan:

On the left[edit]

The throttle, which has a toggle for MASC, if the 'Mech is so equipped. Reverse movement is accomplished by switching the toggle in the front center bank of mode switches to activate reverse mode and pulling back on the throttle. Some 'Mechs will include a secondary Joystick on the left side as well, with the throttle stick moved behind it to accommodate its placement. This secondary stick allows finer control over secondary weapons targeting and arm movements.

The left weapons status display for half of the 'Mech's weapons (and any associated ammunition) with toggles for locking the various weapons into any of the target interlock circuits. This display also shows the recharge or reload status of the weapons it tracks.

The primary screen mode toggles, which controls what is viewed on the primary cockpit screen (the HUD). There is a toggle for active/passive sensor mode, a toggle to activate IFF transponder tracking, and toggles for the various sensor tracking modes, and a toggle for a searchlight (if the 'Mech is so equipped).

Speaker and microphone controls - this controls the pilot's microphone and the 'Mechs external microphones, along with the 'Mech's internal and external speaker systems.

In the center[edit]

Between the MechWarrior's legs on the floor (or hanging from the top of the command chair on some 'Mechs) are the emergency ejection handles, which activate explosive bolts that blow out cockpit panels and disconnects the neurohelmet before ejecting the pilot from the 'Mech. Some BattleMechs, such as the Hatchetman, are designed to eject the entire head of the 'Mech instead of just the command chair, providing greater protection for the MechWarrior in hostile environments.

The computer message relay which relays status information from the 'Mechs DI computer on the 'Mechs condition.

The main control switches - reverse movement mode, torso rotation mode, target interlock configuration switch, sensor configuration switch, and the overheat lockout over-ride.

The primary view screen (the HUD). The targeting reticule, tracking display, and other information readouts are displayed here. Alternative sensor modes, indicators, and tags are also possible on this screen. This is also the polarized cockpit central view screen, which, along with the other view screens, is darkened in response to blinding flashes of light. Target lock quality is usually indicated by color-coding of the reticule. Red is normally indicative of poor or no weapons tracking, while Gold (along with an audible) is usually indicative of the best weapons tracking.

The 'Mech's heat readout, below the primary view screen.

The secondary view screen and its controls, below the heat readout indicator and HUD. This screen usually monitors the 'Mech's armor and systems status, sensor readouts, target 'Mech status, and other functions.

The battle computer keypad and information storage input slot, below the secondary view screen. This keypad interfaces with the DI computer. Information readout for this is on the secondary view screen. This keypad is used to normally used to control the 'Mech's security systems and to transfer control of functions between the various 'Mech computer systems.

The Anti-missile warning system, on 'Mechs equipped with AMS. It lights to indicate incoming missiles, has an AMS ammunition readout and a toggle for activating/deactivating the system.

Physical combat and interaction mode switches - these activate the physical combat modes which switch the foot pedals and joysticks to control kicking, punching, and carrying, and other similar functions. Waldo gloves, located on either side of the command couch, are used on older 'Mechs for more intricate arm and hand controls; while newer 'Mechs have more capable computers, programming, and sensor controls that allow for some more complex movements such as grasping an improvised club, carefully carrying an unconscious pilot, or engaging in large-scale battlefield engineering, all without much pilot input. Physical combat is otherwise a simple point at the target you want and pull the trigger to kick or punch affair. Engaging any of these modes activates a boosted neurohelmet priority mode for greater feedback to the pilot and greater control by the pilot.

Gyroscope start up and calibration controls, for starting up the gyroscope and controlling the level of balance input to the 'Mech from the neurohelmet.

The foot pedals, on the floor at the front, which control turning, kick mode, and jump jets. To turn you depress the pedal on the side you wish to turn to (push down on the left pedal to turn left). The pedals can be unlocked and can tilt, swivel, or otherwise pivot in order to control other movement modes, such as side stepping and more complex functions. Depressing both pedals quickly all the way to the floor activates the 'Mechs jump jets. Once activated, left and right feathering of the jump jets is achieved by depressing either the left or right foot pedal. It is also possible to indicate a landing target with the main or secondary joystick via point and click while in jump mode. The 'Mech will attempt to land at the target area indicated. The jump jets are deactivated by quickly depressing both foot pedals to the floor again.

DI computer access and control panel - this allows the MechWarrior to activate or deactivate the DI computer.

Security circuit control - down near the foot pedals, it contains the hardware with the 'Mechs security access codes.

On the right[edit]

The main joystick. This is the primary control for targeting the weapons systems and control of the 'Mech's arms. It has firing triggers for each of the target interlock circuits (TIC), with as many as six triggers. Weapons aiming is achieved by using this stick to "point" with the reticule on the primary view screen and "clicking" with the desired weapons triggers. The finger rests are sensitive and are used to help control the 'Mech's hands in physical modes. When in physical mode the joystick moves up and down as well as side to side.

The right weapons status display for half of the 'Mech's weapons (and any associated ammunition) with toggles for locking the various weapons into any of the target interlock circuits. This display also shows the recharge or reload status of the weapons it tracks.

Emergency ammo dumping control - used in conjunction with the left and right weapons status displays to eject unused ammo.

Communications controls - used to interact with and control communications networks which the 'Mech is capable of interacting with, be they conventional RF (radio frequency), satellite, microwave, laser link, or land line hookup and the various secure communications modes these methods employ. Some neurohelmets include sensors that facilitate channel switching. ECM, Tag, C3/C3i, standard jamming modes, communications interception and decryption, and Artemis IV/V fire control systems are associated with the communications controls.

Life support controls - these control the cockpit environmental systems and give a readout of the cockpit temperature and life support systems status.

Coolant lines hookup and control - the MechWarrior's coolant vest is attached to and controlled from this panel.

The emergency cockpit blast away system - activates the explosive bolts on the cockpit view ports but does not activate the ejection system.

Ignition switch - a large red bar which is used to bring the fusion reactor up to minimal operational levels which powers the gyro and cockpit systems for BattleMech startup. It locks into place upon startup.

The rear cockpit wall[edit]

The neurohelmet cable hookup, known by the acronym NCCI. This hookup is designed such that the cables will break away cleanly if they do not automatically disconnect in the event of emergency pilot ejection.

The air supply and recirculation system which contains about ten hours of air in tanks and a recirculator which filters and brings in external air when in atmosphere.

The potty - self explanatory.

Lockers, storage space, and cargo netting.

The command Chair[edit]

These are designed to move in order to compensate for shocks and they have a full seat belt harness to hold the MechWarrior In place. Built into the seat is an emergency rocket ejection system, a parachute or rockets for landing, a homing beacon under the seat cushion, and the aforementioned storage locker. There is also a pistol holster (most clan 'Mechs don't have this feature). The seat cushions double as personal flotation devices.

Overall 'Mech functionality[edit]

Structure, actuators and myomers for mobility; armor; gyroscope; the fusion engine; the commanding cockpit; the Battle Computer for Targeting and Tracking; and the DI computer. The neurohelmet can not function as a direct brain-machine link. Well, then, what coordinates all these systems? The DI computer.

BattleMechs are actually quite capable well-programmed robots, with most of that capability stemming from the DI computer network and programming. That said, 'Mechs are not built or programmed to be autonomous, mostly because they carry a huge amount of firepower and are so large. MechWarriors handle all of the higher-level decisions, essentially handling "higher level thinking" and balance tasks for their 'Mech. What the BattleMech computers do handle is a massive amount of lower-level decision making.

The Battle Computer system sorts, processes and translates sensor data and displays it for the MechWarrior, so that the MechWarrior needs only look at his readouts to ascertain his situation on the battlefield. Targeting for a MechWarrior is a simple act of using a control stick to aim a reticule on his targeting display... it is the BattleMech that actually does the calculations and tries to aim the weapons at the target the MechWarrior is indicating. It is the BattleMech that does the majority of recoil compensation and compensates for blasts of incoming hostile fire. While a MechWarrior can help the BattleMech balance, such as telling the 'Mech when to ride with recoil rather than leaning into it, or when to throw itself off-balance at another 'Mech, it is still the DI that handles most of this sort of decision making.

Moving is yet another task that the BattleMech does a lot of work at. Though a BattleMech may have proportionately large feet, it still must choose every footstep with care in order to compensate for outside forces or in anticipation of environmental features. Again, it is the DI that handles this, via a 'Mech's many sensors. Hand actuators are also tools that the BattleMech will handle via the DI network, especially more modern 'Mechs, which are programmed with very capable and complex actuator routines. BattleMechs will actually move their limbs and torso to avoid collisions. The agile movements of a light BattleMech threading its way through a forest is not only the result of a talented MechWarrior, but the 'Mech's own DI computer avoiding the trees.

However, BattleMechs do sometimes simply crash their way through forests, clip buildings, or trip down into ravines. This is because BattleMechs are programmed to obey their pilots, regardless of the "common sense" programmed into the 'Mech. For instance, a 'Mech will swing its arms through the side of a building if that is what's required to bring weapons to bear on a target. BattleMechs will give collision warnings, but they don't override their pilots. Ironically, this is one of the reasons why it takes a long time to train good MechWarriors. MechWarriors actually have to learn how to think for their 'Mech and exploit the machine's "intelligence" in order to get the results they want.