Editing Tank (section)

==Design==
[[File:M1 Abrams-TUSK.svg|upright=2|thumb|Labelled diagram of an M1 Abrams]]

The three traditional factors determining a tank's capability effectiveness are its ''firepower'', ''protection'', and ''mobility''.<ref>{{Cite book|title=Tiger Tank Battalions in World War II|last=Forty|first=George|publisher=Compendium Publishing, Ltd.|year=2008|isbn=978-0-7603-3049-4|location=London|pages=107}}</ref><ref>{{Cite book|title=Blood, Sweat and Arrogance: The Myths of Churchill's War|last=Corrigan|first=Gordon|publisher=Weidenfeld & Nicolson|year=2012|isbn=978-1-78022-555-5|location=London}}</ref> Firepower is the ability of a tank's crew to identify, engage, and destroy enemy tanks and other targets using its large-caliber cannon. Protection is the degree to which the tank's armour, profile and camouflage enables the tank crew to evade detection, protect themselves from enemy fire, and retain vehicle functionality during and after combat. Mobility includes how well the tank can be transported by rail, sea, or air to the operational staging area; from the staging area by road or over terrain towards the enemy; and tactical movement by the tank over the battlefield during combat, including traversing of obstacles and rough terrain. The variations of tank designs have been determined by the way these three fundamental features are blended. For instance, in 1937, the French doctrine focused on firepower and protection more than mobility because tanks worked in intimate liaison with the infantry.<ref>{{Cite book|title=The Seeds of Disaster: The Development of French Army Doctrine, 1919–39|author1-link=Robert A. Doughty|last=Doughty|first=Robert|publisher=Stackpole Books|year=1985|isbn=978-0-8117-1460-0|location=Mechanicsburg, PA|pages=162}}</ref> There was also the case of the development of a heavy cruiser tank, which focused on armour and firepower to challenge Germany's Tiger and Panther tanks.<ref>{{Cite book|title=The Centurion Tank|last=Ware|first=Pat|publisher=Pen & Sword Military|year=2012|isbn=978-1-78159-011-9|location=South Yorkshire|pages=7–8}}</ref>

===Classification===
{{main|Tank classification}}
{{unreferenced section|date=August 2017}}
[[File:Purwarupa Harimau MT saat FAT (Factory Acceptance Test) 24 - 25 Februari 2022.jpg|thumb|[[Kaplan MT / Harimau|The Kaplan/Harimau tank]] made in [[Indonesia]] and [[Turkey|Türkiye]] is a medium-quality tank programmed for areas that are difficult for large tanks to reach.]]
Tanks have been classified by weight, role, or other criteria, that has changed over time and place. Classification is determined by the prevailing theories of armoured warfare, which have been altered in turn by rapid advances in technology. No one classification system works across all periods or all nations; in particular, weight-based classification is inconsistent between countries and eras.

In World War I, the first tank designs focused on crossing wide trenches, requiring very long and large vehicles, such as the British Mark I; these became classified as [[heavy tank]]s. Tanks that fulfilled other combat roles were smaller, like the French Renault FT; these were classified as [[light tank]]s or [[tankette]]s. Many late-war and inter-war tank designs diverged from these according to new, though mostly untried, concepts for future tank roles and tactics. Tank classifications varied considerably according to each nation's own tank development, such as "cavalry tanks", "fast tanks", and "breakthrough tanks".

During World War II, many tank concepts were found unsatisfactory and discarded, mostly leaving the more multi-role tanks; these became easier to classify. Tank classes based on weight (and the corresponding transport and logistical needs) led to new definitions of heavy and light tank classes, with [[medium tank]]s covering the balance of those between. The British maintained [[cruiser tank]]s, focused on speed, and [[infantry tank]]s that traded speed for more armour. [[Tank destroyer]]s are tanks or other [[armoured fighting vehicle]]s specifically designed to defeat enemy tanks. [[Assault gun]]s are armoured fighting vehicles that could combine the roles of infantry tanks and [[tank destroyer]]s. Some tanks were converted to [[flame tank]]s, specializing on close-in attacks on enemy strongholds with [[flamethrower]]s. As the war went on, tanks tended to become larger and more powerful, shifting some tank classifications and leading to [[super-heavy tank]]s.

Experience and technology advances during the [[Cold War]] continued to consolidate tank roles. With the worldwide adoption of the modern [[main battle tank]] designs, which favour a modular universal design, most other classifications are dropped from modern terminology. All main battle tanks tend to have a good balance of speed, armour, and firepower, even while technology continues to improve all three. Being fairly large, main battle tanks can be complemented with light tanks, [[armoured personnel carrier]]s, [[infantry fighting vehicle]]s or similar relatively lighter armoured fighting vehicles, typically in the roles of [[armoured reconnaissance]], [[Amphibious warfare|amphibious]] or [[air assault]] operations, or against enemies lacking main battle tanks.

===Offensive capabilities===
{{Main|Tank gun}}

[[File:105mm tank gun Rifling.jpg|thumb|upright| A sectioned 105mm [[rifling|rifled]] [[Royal Ordnance L7]] tank gun]]

The [[tank gun|main weapon]] of modern tanks is typically a single, large-[[caliber]] [[cannon]] mounted in a [[Gun laying|fully traversing]] (rotating) [[gun turret]]. The typical modern tank gun is a [[smoothbore]] weapon capable of firing a variety of ammunition, including [[armour-piercing]] [[kinetic energy penetrator]]s (KEP), also known as [[armour-piercing discarding sabot]] (APDS), and/or [[APFSDS|armour-piercing fin-stabilized discarding sabot]] (APFSDS) and [[high-explosive anti-tank]] (HEAT) [[shell (projectile)|shells]], and/or [[high-explosive squash head]] (HESH) and/or [[anti-tank guided missile]]s (ATGM) to destroy armoured targets, as well as [[High-explosive fragmentation|high-explosive]] (HE) [[High-explosive fragmentation|shells]] for shooting at "soft" targets (unarmoured vehicles or troops) or [[fortifications]]. [[Canister shot]] may be used in close or urban combat situations where the risk of hitting friendly forces with [[Shrapnel (fragment)|shrapnel]] from HE rounds is unacceptably high.<ref name = "USAToday2005b">[[#USAToday2005b|USA Today (2005)]], ''Tanks adapted for urban fights they once avoided''</ref>

A [[gyroscope]] is used to stabilise the main gun, allowing it to be effectively aimed and fired at the "short halt" or on the move. Modern tank guns are also commonly fitted with [[thermal insulation|insulating]] [[thermal sleeve]]s to reduce gun-barrel warping caused by uneven [[thermal expansion]], [[bore evacuator]]s to minimise gun firing fumes entering the crew compartment and sometimes [[muzzle brake]]s to minimise the effect of [[recoil]] on accuracy and [[rate of fire]].

[[File:German Leopard 2A6 from 3rd Panzer Battalion fires it's main gun during the shoot-off of Strong Europe Tank Challenge (40964003420) (cropped).jpg|left|thumb|German [[Leopard 2]]A6 from a Panzerbattalion fires its main gun during the shoot-off of [[Strong Europe Tank Challenge]].]]
[[File:Flickr - Israel Defense Forces - 188th Brigade Training Day, March 2008-cropped.jpg|thumb|left|A [[Merkava]] Mk IIID Baz firing]]
Traditionally, target detection relied on visual identification. This was accomplished from within the tank through [[telescope|telescopic]] [[periscope]]s; often, however, tank commanders would open up the hatch to view the outside surroundings, which improved situational awareness but incurred the penalty of vulnerability to sniper fire. Though several developments in target detection have taken place, these methods are still common practice. In the 2010s, more electronic target detection methods are available.

In some cases [[spotting rifle]]s were used to confirm proper trajectory and range to a target. These spotting rifles were mounted co-axially to the main gun, and fired [[tracer ammunition]] ballistically matched to the gun itself. The gunner would track the movement of the tracer round in flight, and upon impact with a hard surface, it would give off a flash and a puff of smoke, after which the main gun was immediately fired. However this slow method has been mostly superseded by [[laser rangefinder|laser rangefinding]] equipment.

Modern tanks also use sophisticated [[night vision device|light intensification]] and [[thermal imaging]] equipment to improve fighting capability at night, in poor weather and in smoke. The accuracy of modern tank guns is pushed to the mechanical limit by computerized [[fire-control system]]s. A fire-control system uses a laser rangefinder to determine the range to the target, a [[thermocouple]], [[anemometer]] and [[wind vane]] to correct for weather effects and a muzzle referencing system to correct for gun-barrel temperature, warping and wear. Two sightings of a target with the range-finder enable calculation of the target movement [[Vector (geometric)|vector]]. This information is combined with the known movement of the tank and the principles of [[External ballistics|ballistics]] to calculate the [[elevation (ballistics)|elevation]] and [[Aiming point|aim point]] that maximises the probability of hitting the target.

Usually, tanks carry smaller caliber armament for short-range defense where fire from the main weapon would be ineffective or wasteful, for example when engaging [[infantry]], [[Armoured car (military)|light vehicles]] or [[close air support]] aircraft. A typical complement of secondary weapons is a general-purpose machine gun mounted [[coaxial weapon|coaxially]] with the main gun, and a heavier [[anti-aircraft]]-capable machine gun on the turret roof. Some tanks also have a hull-mounted machine gun. These weapons are often modified variants of those used by infantry, and so use the same kinds of ammunition.

===Protection and countermeasures===
[[File:T-90 tank during the Victory Day parade in 2009.jpg|thumb|right|The Russian [[T-90]] is fitted with a "three-tiered" protection systems:<br />1: [[Composite armour]] in the turret<br /> 2: Third generation [[Kontakt-5]] [[explosive reactive armour|ERA]]<br /> 3: [[Shtora]]-1 countermeasures suite.]]

{{See also|Anti-tank warfare}}
The measure of a tank's protection is the combination of its ability to avoid detection (due to having a low profile and through the use of camouflage), to avoid being hit by enemy fire, its resistance to the effects of enemy fire, and its capacity to sustain damage whilst still completing its objective, or at least protecting its crew. This is done by a variety of countermeasures, such as armour plating and reactive defenses, as well as more complex ones such as heat-emissions reduction.

In common with most unit types, tanks are subject to additional hazards in dense wooded and urban combat environments which largely negate the advantages of the tank's long-range firepower and mobility, limit the crew's detection capabilities and can restrict turret traverse. Despite these disadvantages, tanks retain high [[survivability]] against previous-generation [[rocket-propelled grenade]]s aimed at the most-armoured sections.

However, as effective and advanced as armour plating has become, tank survivability against newer-generation [[tandem-warhead]] anti-tank missiles is a concern for military planners.<ref>[[#BBCNews2006|BBC News (2006)]] ''Tough lessons for Israeli armour''</ref> Tandem-warhead RPGs use two warheads to fool active protection systems; a first dummy warhead is fired first, to trigger the active defenses, with the real warhead following it. For example, the [[RPG-29]] from the 1980s is able to penetrate the frontal hull armour of the Challenger II<ref>{{cite news|title=MoD kept failure of best tank quiet|author=Sean Rayment|work=[[Sunday Telegraph]]|date=12 May 2007|url=https://www.telegraph.co.uk/news/uknews/1551418/MoD-kept-failure-of-best-tank-quiet.html|url-status=live|archive-url=https://web.archive.org/web/20150704200640/http://www.telegraph.co.uk/news/uknews/1551418/MoD-kept-failure-of-best-tank-quiet.html|archive-date=4 July 2015}}</ref> and also managed to damage a M1 Abrams.<ref>{{cite news |title=Operation in Sadr City Is an Iraqi Success, So Far |author=Michael R. Gordon |work=[[The New York Times]] |date=21 May 2008 |url=https://www.nytimes.com/2008/05/21/world/middleeast/21sadr.html?_r=2&hp&oref=slogin&oref=slogin |url-status=live |archive-url=https://web.archive.org/web/20170623214243/http://www.nytimes.com/2008/05/21/world/middleeast/21sadr.html?_r=2&hp&oref=slogin&oref=slogin |archive-date=23 June 2017 }}</ref> As well, even tanks with advanced armour plating can have their tracks or gear cogs damaged by RPGs, which may render them immobile or hinder their mobility. Despite all of the advances in armour plating, a tank with its hatches open remains vulnerable to [[Molotov cocktail]] (gasoline bombs) and grenades. Even a "buttoned up" tank may have components which are vulnerable to Molotov cocktails, such as optics, extra gas cans and extra ammunition stored on the outside of the tank.

====Avoiding detection====
{{Further|Military deception}}
[[File:Type 99 MBT front right.jpg|thumb|left|[[People's Liberation Army|PLA]]'s [[Type 99a tank]] with [[disruptive coloration|disruptive]] camouflage painting]]
A tank avoids detection using the doctrine of [[countermeasure]]s known as CCD: [[military camouflage|camouflage]] (looks the same as the surroundings), concealment (cannot be seen) and deception (looks like something else).

=====Camouflage=====
{{further|Military camouflage}}
[[File:Challenger 2-Megatron MOD 45161486.jpg|alt=|thumb|A British [[Challenger 2]] Theatre Entry Standard fitted with a mobile camouflage system.]]
Camouflage can include disruptive painted shapes on the tank to break up the distinctive appearance and silhouette of a tank. Netting or actual branches from the surrounding landscape are also used. Prior to development of infrared technology, tanks were often given a coating of camouflage paint that, depending on environmental region or season, would allow it to blend in with the rest of its environment. A tank operating in wooded areas would typically get a green and brown paintjob; a tank in a winter environment would get white paint (often mixed with some darker colors); tanks in the desert often get khaki paintjobs.

The Russian [[Nakidka]] camouflage kit was designed to reduce the [[optical]], [[Thermal radiation|thermal]], [[infrared]], and [[radar]] signatures of a tank, so that acquisition of the tank would be difficult. According to Nii Stali, the designers of Nakidka, Nakidka would reduce the probabilities of detection via "visual and near-IR bands by 30%, the thermal band by 2–3-fold, radar band by 6-fold, and radar-thermal band to near-background levels.<ref>[https://web.archive.org/web/20090707002753/http://www.niistali.ru/pr_secure/nobron_en.htm#7 "Nakidka" kit for protection against surveillance and precision-guided systems](archive)</ref>

=====Concealment=====
{{unreferenced section|date=November 2018}}

Concealment can include hiding the tank among trees or digging in the tank by having a combat bulldozer dig out part of a hill, so that much of the tank will be hidden. A tank commander can conceal the tank by using "hull down" approaches to going over upward-sloping hills, so that she or he can look out the commander's cupola without the distinctive-looking main cannon cresting over the hill. Adopting a turret-down or [[hull-down]] position reduces the visible silhouette of a tank as well as providing the added protection of a position in [[Enfilade and defilade#Defilade|defilade]].

Working against efforts to avoid detection is the fact that a tank is a large metallic object with a distinctive, angular [[silhouette]] that emits copious [[thermal imaging|heat]] and engine noise. A tank that is operating in cold weather or which needs to use its radio or other communications or target-detecting electronics will need to start its engine regularly to maintain its battery power, which will create engine noise. Consequently, it is difficult to effectively camouflage a tank in the absence of some form of cover or concealment (e.g., woods) it can [[hull-down|hide]] its hull behind. The tank becomes easier to detect when moving (typically, whenever it is in use) due to the large, distinctive auditory, vibration and thermal signature of its engine and power plant. Tank tracks and dust clouds also betray past or present tank movement.

Switched-off tanks are vulnerable to infra-red [[thermal imaging|detection]] due to differences between the [[thermal conductivity]] and therefore [[heat#Heat dissipation|heat dissipation]] of the metallic tank and its surroundings. At close range the tank can be detected even when powered down and fully concealed due to the [[heat haze|column of warmer air]] above the tank and the smell of diesel or gasoline. Thermal blankets slow the rate of heat emission and some thermal camouflage nets use a mix of materials with differing thermal properties to operate in the infra-red as well as the [[visible spectrum]].

[[Grenade launcher]]s can rapidly deploy a [[smoke screen]] that is opaque to [[infrared]] light, to hide it from the thermal viewer of another tank. In addition to using its own grenade launchers, a tank commander could call in an artillery unit to provide smoke cover. Some tanks can produce a smoke screen.

Sometimes camouflage and concealment are used at the same time. For example, a camouflage-painted and branch-covered tank (camouflage) may be hidden in a behind a hill or in a dug-in-emplacement (concealment).

=====Deception=====
[[File:E04934.jpg|thumb|right|upright=0.9|Troops carry a lightweight wood-framed "dummy" tank into position.]]
Some [[armoured recovery vehicle]]s (often tracked, tank chassis-based "tow trucks" for tanks) have dummy turrets and cannons. This makes it less likely that enemy tanks will fire on these vehicles. Some armies have fake "dummy" tanks made of wood which troops can carry into position and hide behind obstacles. These "dummy" tanks may cause the enemy to think that there are more tanks than are actually possessed.

====Armour====
{{unreferenced section|date=January 2013}}
{{Main|Vehicle armour}}
{{multiple image|perrow = 2|total_width=300
| image1 = M1 Abrams Hull Front Special Armor.jpg
| image2 = M1 Abrams Turret Bustle Side Special Armor.png
| image3 = M1 Abrams Hull Side Special Armor.jpg
| image4 = M1 Abrams Gun Shield Special Armor.jpg
| footer = Configuration of M1 Abrams [[Chobham armor|Chobham]] Special Armor. Clockwise from upper left: Hull front, turret bustle, hull side, gun shield.
}}
[[File:Challenger2-Bergen-Hohne-Training-Area-2.jpg|thumb|right|The British [[Challenger 2|Challenger II]] is protected by second-generation [[Chobham armour]]]]

To effectively protect the tank and its crew, tank armour must counter a wide variety of antitank threats. Protection against [[kinetic energy penetrator]]s and [[high-explosive anti-tank]] (HEAT) shells fired by other tanks is of primary importance, but tank armour also aims to protect against infantry [[Mortar (weapon)|mortars]], [[grenades]], [[rocket-propelled grenade]]s, [[anti-tank guided missile]]s, [[land mine|anti-tank mines]], [[anti-tank rifles]], [[bomb]]s, direct [[artillery]] hits, and (less often) [[Weapon of mass destruction|nuclear, biological and chemical]] threats, any of which could disable or destroy a tank or its crew.

[[rolled homogeneous armour|Steel armour plate]] was the earliest type of armour. The Germans pioneered the use of [[carbon steel#Case hardening|face hardened]] steel during World War II and the Soviets also achieved improved protection with [[sloped armour]] technology. World War II developments led to the obsolescence of homogeneous steel armour with the development of [[shaped-charge]] warheads, exemplified by the [[Panzerfaust]] and [[bazooka]] infantry-carried weapons which were effective, despite some early success with [[spaced armour]]. Magnetic mines led to the development of [[diamagnetism|anti-magnetic]] paste and paint. From WWII to the modern era, troops have added improvised armour to tanks while in combat settings, such as sandbags or pieces of old armour plating.

British tank researchers took the next step with the development of [[Chobham armour]], or more generally [[composite armour]], incorporating [[ceramic]]s and plastics in a [[resin]] matrix between steel plates, which provided good protection against HEAT weapons. [[High-explosive squash head]] warheads led to [[spall|anti-spall]] armour linings, and kinetic energy penetrators led to the inclusion of exotic materials like a matrix of [[depleted uranium]] into a composite armour configuration.

[[File:M60A1-Patton-Blazer-latrun-2.jpg|thumb|Blazer [[explosive reactive armour]] (ERA) blocks on an Israeli M-60]]
[[Reactive armour]] consists of small explosive-filled metal boxes that detonate when hit by the metallic jet projected by an exploding HEAT warhead, causing their metal plates to disrupt it. [[Tandem warhead]]s defeat reactive armour by causing the armour to detonate prematurely. Modern reactive armour protects itself from Tandem warheads by having a thicker front metal plate to prevent the precursor charge from detonating the explosive in the reactive armour. Reactive armours can also reduce the penetrative abilities of [[kinetic energy penetrator]]s by deforming the penetrator with the metal plates on the Reactive armour, thereby reducing its effectiveness against the main armour of the tank.

====Active protection system====
[[File:Flickr - Israel Defense Forces - Storming Ahead.jpg|thumb|right|[[Israel Defense Forces|IDF]] [[Merkava]] Mk4 tank with [[Trophy (countermeasure)|Trophy]] [[active protection system|APS]] ("מעיל רוח") during training]]

The latest generation of protective measures for tanks are [[active protection system]]s. The term "active" is used to contrast these approaches with the armour used as the primary protective approach in earlier tanks.
* [[Soft kill]] measures, such as the Russian [[Shtora]] countermeasure system, provide protection by interfering with enemy targeting and fire-control systems, thus making it harder for the enemy threats to lock onto the targeted tank.
* Hard kill systems intercept incoming threats with a projectile(s) of its own, destroying the threat. For example, the Israeli [[Trophy (countermeasure)|Trophy]] destroys an incoming rocket or missile with shotgun-like projectiles. The Soviet [[Drozd]], the Russian [[Arena active protection system|Arena]], the Israeli [[Trophy (countermeasure)|Trophy]] and [[Iron Fist (countermeasure)|Iron Fist]], Polish [[ERAWA]], and the American [[Quick Kill]] systems show the potential to dramatically improve protection for tanks against [[anti-tank missile|missiles]], [[rocket-propelled grenade|RPGs]] and potentially kinetic energy penetrator attacks, but concerns regarding a [[Friendly fire|danger zone for nearby troops]] remain.{{citation needed|date=June 2015}}

===Mobility===
[[File:Zwei Leopard 2A5 beim durchqueren eines Gewässer.ogv|thumb|right|Two [[German Army]] Leopard 2s demonstrate their [[Amphibious vehicle#Deep fording|deep-wading]] capabilities]]

The mobility of a tank is described by its battlefield or tactical mobility, its operational mobility, and its strategic mobility.<ref name="logistics_burden">{{cite book |date= 1999 |title= Reducing the Logistics Burden for the Army After Next: Doing More with Less|url=https://nap.nationalacademies.org/read/6402/chapter/1 |location=Washington, DC, USA |publisher=National Academy Press |doi= 10.17226/6402|isbn=9780309063784}}</ref>
* '''Tactical mobility''' is the tank's ability to move through the battle area. This could include acceleration, braking, speed and rate of turn on varying terrain, and obstacle clearance: the tank's ability to travel over or through obstacles like walls, trenches, and water.
* '''Operational mobility''' is the ability to move tanks hundreds of kilometers from a staging area to the battle area, for example, by using transport helicopters. 
* '''Strategic mobility''' is the ability of the tanks to be transported over long distances, usually by air or sea. For tanks to be transported efficiently by air, weight and volume must be kept within the transport aircraft's capabilities.<ref name="logistics_burden" />

[[File:M1 strategic mobility.jpg|thumb|right|[[M1 Abrams]] offloading from [[Landing Craft Air Cushioned]] vehicle.]]
Tanks have high tactical  mobility and can travel over most types of terrain due to their [[continuous track]]s and advanced suspension. The tracks disperse the weight of the vehicle over a large area, resulting in less [[ground pressure]]. A tank can travel at approximately {{convert|40|km/h|mph}} across flat terrain and up to {{convert|70|km/h|mph}} on roads, but due to the mechanical strain this places on the vehicle and the logistical strain on fuel delivery and tank maintenance, these must be considered exceptional "burst" speeds.

Tanks are susceptible to mechanical failure of engine and transmission systems, particularly at maximum burst speeds. Consequently, wheeled tank transporters and rail transport are used wherever possible for non-combat tank transport. Tank mobility is very restricted compared to wheeled [[armoured fighting vehicle]]s. Most operational mobility in blitzkrieg tank operations was conducted at the pedestrian pace of {{convert|5|km/h|mph}}, and that was only achieved on the roads of France.<ref>[[#Deighton1979|Deighton (1979)]], ''Blitzkrieg, From the rise of Hitler to the fall of Dunkirk'', p. 180</ref>
[[File:M88 pulling M1 engine.jpg|right|thumb|The [[M1 Abrams]] is powered by a {{convert|1500|shp}} [[Honeywell]] [[AGT-1500|AGT 1500]] gas turbine engine, giving it a governed top speed of {{convert|45|mph|km/h|abbr=on}} on paved roads, and {{convert|30|mph|km/h|abbr=on}} cross-country.]]

===Suspension and running gear===

Tank agility is a function of the weight of the tank due to its inertia while manoeuvring and its [[ground pressure]], the power output of the installed power plant and the tank [[Transmission (mechanics)|transmission]] and [[Continuous track|track]] design. In addition, rough terrain effectively limits the tank's speed through the stress it puts on the [[suspension (vehicle)#Armoured fighting vehicle suspension|suspension]] and the crew. A breakthrough in this area was achieved during World War II when improved suspension systems were developed that allowed better cross-country performance and limited firing on the move. Systems like the earlier [[Christie suspension|Christie]] or later [[torsion-bar]] suspension developed by [[Ferdinand Porsche]] dramatically improved the tank's cross-country performance and overall mobility.<ref>[[#Deighton1979|Deighton (1979)]], ''Blitzkrieg, From the rise of Hitler to the fall of Dunkirk'', p. 154</ref>

=== Engine ===
The tank's power plant supplies [[kinetic energy]] to move the tank, and [[electric current|electric]] power via a [[Electrical generator#Vehicle-mounted generators|generator]] to components such as the [[gun turret|turret]] rotation motors and the tank's electronic systems.

The tank power plant evolved from predominantly petrol and adapted large-displacement aeronautical or automotive [[internal combustion engines|engines]] to [[diesel engine]]s. Japan was the first to begin transitioning to this engine type beginning with the [[Type 89B]] in 1934. The main advantage of diesel is their higher [[fuel efficiency|fuel economy]], which allows for greater operating ranges. Diesel engines can also run on a variety of fuels, such as aviation kerosene and even gasoline. Advanced [[multi-fuel]] [[Diesel engine#Quality and variety of fuels|diesel engines]] have been adopted.{{sfn|Ogorkiewicz|1991|p=247-249}} [[Gas turbine#Tanks|Gas turbines]] are powerful per unit weight but fuel-hungry; they have been used in a few tanks, including the Soviet [[T-80]] and American [[M1 Abrams]].

{| class="wikitable" style="text-align:center;"
|-
|+Tank power output and [[torque]] in context:{{citation needed|date=December 2013}}
|-
! colspan=2 |Vehicle
! Power output
! Power/weight
!Torque
|-
! Mid-sized car 
| [[Toyota Camry]] 2.4&nbsp;L
| {{convert|158|hp|kW|order=flip|abbr=on}}
| {{convert|106|hp/t|kW/t|order=flip|abbr=on}}
| {{convert|218|Nm|abbr=on}}
|-
! Sports car 
| [[Lamborghini Murciélago]] 6.5&nbsp;L
| {{convert|632|hp|kW|order=flip|abbr=on}}
| {{convert|383|hp/t|kW/t|order=flip|abbr=on}}
| {{convert|660|Nm|abbr=on}}
|-
! Racing car 
| [[Formula One car]] 3.0&nbsp;L
| {{convert|950|hp|kW|order=flip|abbr=on}}
| {{convert|1428|hp/t|kW/t|order=flip|abbr=on}}
| {{convert|350|Nm|abbr=on}}
|-
! Main battle tank 
| [[Leopard 2]], [[M1 Abrams]]
| {{convert|1500|hp|kW|order=flip|abbr=on}}
| {{convert|24.2|to|24.5|hp/t|kW/t|order=flip|abbr=on}}
| {{convert|4700|Nm|abbr=on}}
|-
! Locomotive 
| [[SNCF Class T 2000]]
| {{convert|2581|hp|kW|order=flip|abbr=on}}
| {{convert|11.5|hp/t|kW/t|order=flip|abbr=on}}
|
|}

===Fording===
In the absence of [[combat engineer]]s, most tanks can only [[Ford (crossing)|ford]] small rivers. The typical fording depth for MBTs is approximately {{convert|1|m|ft|abbr=on}}, being limited by the height of the engine air intake and driver's position. Modern tanks such as the Russian [[T-90]] and the German [[Leopard 1]] and [[Leopard 2]] tanks can ford to a depth of {{convert|3|to|4|m|ft|abbr=on}} when properly prepared and equipped with a [[Vehicle snorkel|snorkel]] to supply air for the crew and engine. Tank crews usually strongly dislike deep fording, but it adds considerable scope for [[List of military tactics|surprise]] and tactical flexibility in water-crossing operations by opening new and unexpected avenues of attack.

[[Amphibious tank]]s are specially designed or adapted for water operations, such as by including snorkels and skirts, but they are rare in modern armies. Purpose-built [[amphibious assault vehicle]]s or [[armoured personnel carrier]]s are used, without tanks, in [[Amphibious warfare#Post–World War II|amphibious assaults]]. Advances such as the [[EFA (mobile bridge)|EFA mobile bridge]] and [[Armoured vehicle-launched bridge|armoured vehicle-launched scissors bridges]] have also reduced the impediment to tank advance that rivers posed in World War II.<ref>[[#Deighton1979|Deighton (1979)]], ''Blitzkrieg, From the rise of Hitler to the fall of Dunkirk'', pp. 234–52</ref>

===Crew===
{{redirect|Tank commander}}
[[File:Leclerc-IMG 1717.jpg|thumb|The tank commander's position in an [[AMX Leclerc]]]]
[[File:T72B3-Crew.svg|thumb|Positions of crew members in a Russian [[T-72]]B3 tank. The driver (3) is seated in the front, commander (1) and gunner (2) are in the turret, directly above the carousel (4), which contains the ammunition for the autoloading mechanism.]]
{{Army units}}
Most modern tanks most often have four crew members, or three if an [[auto-loader]] is installed. These are the:
* [[Commanding officer|Commander]] – The commander is responsible for commanding the tank, with all-round vision devices rather than the limited vision of the driver and gunner. He guides the gunner roughly onto target and guides the driver around turns and obstacles.
* [[Gunner (artillery)|Gunner]] – The gunner is responsible for [[Gun laying|laying (aiming) the gun]]. It may be laying for direct fire, where the gun is aimed similarly to a rifle, or indirect fire, where firing data is calculated and applied to the sights. The term includes automated aiming using, for example, radar-derived target data and computer-controlled guns. Gun laying involves moving the axis of the bore of the barrel in two planes, horizontal and vertical. A gun is "traversed" (rotated in a horizontal plane) to align it with the target, and "elevated" (moved in the vertical plane) to range it to the target.
* Loader – The loader loads the gun, with a round appropriate to the target (HEAT, smoke, etc.) as ordered by either the commander or the gunner. The loader is usually the lowest-ranked member of the crew. In tanks with auto-loaders this position is omitted.
* [[Driver (person)|Driver]] – The driver drives the tank, and also performs routine maintenance on the automotive features.
[[File:3rd ID M1A1 Abrams TC and Gunner 2008.jpg|thumb|A view in a M1A1 Abrams tank of the gunner's station (bottom left) and commander's station (top right)]]

Operating a tank is a team effort. For example, the loader is assisted by the rest of the crew in stowing ammunition. The driver is assisted in maintaining the automotive features.<ref>{{cite web|url=http://www.theshermantank.com/sherman/the-crew-and-their-stations-the-human-part-of-the-tank/| title = The Crew And Their Stations: The Human Part Of The Tank, How They Lived, Worked, And Fought| date = 22 November 2015}}</ref>

Historically, crews have varied from two to twelve members. First World War tanks carried the crew needed to man the multiple guns and machine guns, and up to four crewmen  to drive the tank: the commander drove the tank and manned the brakes, steering via orders to his gears-men; a co-driver operated the gearbox and throttle; and two gears-men, one for each track, steered by setting their side to idle, allowing the track on the other side to slew the tank to one side. Pre-World War II French tanks were noted for having a two-man crew, in which the overworked commander had to load and fire the gun in addition to commanding the tank.

With World War II the multi-turreted tanks proved impracticable, and as the single turret on a low hull design became standard, crews became standardized around a crew of four or five. In those tanks with a fifth crew member, usually three were located in the turret (as described above) while the fifth was most often seated in the hull next to the driver, and operated the hull machine gun in addition to acting as a co-driver or radio operator. Well-designed crew stations, giving proper consideration to comfort and ergonomics, are important to the combat-effectiveness of a tank, as they limit fatigue and speed up individual actions.

===Engineering constraints===
[[File:Arjun MBT bump track test.JPG|thumb|The Indian [[Arjun MBT]]'s [[hydropneumatic suspension]] at work, while moving over a bump track.]]
A noted author on the subject of tank design engineering, [[Richard Ogorkiewicz]], outlined the following basic engineering sub-systems that are commonly incorporated into a tank's technological development:{{sfn|Ogorkiewicz|1991|p=}}{{page needed|date=May 2012}}
* Mobility  (through chassis design)
* [[Engine#Combustion engine|Engines]]
* [[Transmission (mechanics)|Transmissions]]
* [[Suspension (vehicle)|Suspensions]] and [[running gear]]
* Soil-vehicle mechanics
* [[Tank gun|Guns]] and [[Ammunition#Ordnance ammunition|ammunition]]
* [[Ballistics]] and mechanics of guns
* Vision and sighting systems
* Illuminating and [[Night Vision#Night vision technologies|night vision]] systems
* [[Fire-control system|Fire control systems]] for main and auxiliary weapons
* [[Gun data computer|Gun control systems]]
* [[Precision-guided munition|Guided weapons]]
* [[Vehicle armour#Armoured fighting vehicles|Armour]] protection
* Configuration
To the above can be added unit communication systems and electronic anti-tank countermeasures, crew ergonomic and survival systems (including flame suppression), and provision for technological upgrading.
Few tank designs have survived their entire service lives without some upgrading or modernization, particularly during wartime, including some that have changed almost beyond recognition, such as the latest Israeli [[Magach#Versions|Magach]] versions.

The characteristics of a tank are determined by the performance criteria required for the tank. The obstacles that must be traversed affect the vehicle's front and rear profiles. The types of terrain specified to be traversed determine the maximum permissible track ground pressure.<ref name="performance reqs">{{Citation|title=Journal of the United Service Institution of India, Volume 98|year=1968|publisher=United Service Institution of India|url=https://books.google.com/books?id=iZI8AQAAIAAJ|page=58|url-status=live|archive-url=https://web.archive.org/web/20180327160324/https://books.google.com/books?id=iZI8AQAAIAAJ|archive-date=27 March 2018}}</ref>

Tank design is a compromise between technological and budgetary constraints and tactical capability requirements. It is not possible to maximise firepower, protection and mobility simultaneously, while also incorporating the latest technology and being economically viable.
For example, in the case of tactical capability requirements, increasing protection by adding armour will result in an increase in weight and therefore decrease in mobility; increasing firepower by installing a larger gun will force the designer team to increase armour, the therefore weight of the tank by retaining same internal volume to ensure crew efficiency during combat. In the case of the Abrams MBT which has good firepower, speed and armour, these advantages are counterbalanced by its engine's notably high fuel consumption, which ultimately reduces its range, and in a larger sense its mobility. And most enhancements add to cost.

Since the Second World War the economics of tank production, governed by the complexity of manufacture and cost and the impact of a given tank design on logistics and field maintenance capabilities, have also been accepted as important in determining how many tanks a nation can afford to field in its force structure.

Some tank designs that were fielded in significant numbers, such as [[Tiger I]] and [[M60A2 Starship|M60A2]] proved to be too complex or expensive to manufacture, and made unsustainable demands on the logistics services support of the armed forces. The ''affordability of the design'' therefore takes precedence over the combat capability requirements.
Nowhere was this principle illustrated better than during the Second World War when two Allied designs, the Soviet [[T-34]] and the US [[M4 Sherman]], although both simple designs which accepted engineering compromises, were used successfully against more sophisticated designs by Germany that were more complex and expensive to produce, and more demanding on overstretched logistics of the Wehrmacht. Given that a tank crew will spend most of its time occupied with maintenance of the vehicle, engineering simplicity has become the primary constraint on tank design since the Second World War despite advances in mechanical, electrical and electronics technologies.

Since the Second World War, tank development has incorporated experimenting with significant mechanical changes to the tank design while focusing on technological advances in the tank's many subsystems to improve its performance. However, a number of novel designs appeared, with mixed success, including the firepower of the Soviet [[IT-1]] and [[T-64]], and the crew protection of the Israeli [[Merkava]] and Swedish [[S-tank]], while for decades the US's [[M551]] remained the only light tank deployable by parachute.

{{Further|Tank classification}}