For the feature with similar functionality, see Crew
Overview
All tanks have modules which are necessary for the tank to perform in battle. These are separate entities from the tank's hull, and the damage or destruction of one of these modules can severely hinder a tank's effectiveness.
Researchable Modules
Engines
The engine is the powerplant of the tank. Its job is to drive the tank's tracks. Destruction of this module will render a tank motionless. Additionally, this module is prone to catching fire when hit, which will gradually damage the tank if it is not extinguished. In the case of the engine's destruction, the tank will drift to a halt, while the tracks, if damaged, immediately stop the tank.
Guns
The gun is arguably the most important module of a tank. Without the gun, a tank would be nothing more than a heavy, tracked vehicle. This module is a tank's main offensive weapon, and destroying this module will limit the tank's offensive capabilities to deal damage.
Suspensions
The suspension (a.k.a. chassis, running gear, or tracks) is the "wheels" of the tank. The largest and (usually) most exposed module of any tank, this module is the most vulnerable to enemy fire. When hit, it has a high chance of being destroyed, which could be bad for you if you are out in the open. If only one track is destroyed, you may be able to use the other track, but this rarely does any good as you can only drive in tight circles.
Turrets
On most tanks, the turret houses the gun. Most turrets allow for a full 360 degrees of aiming freedom, but if the turning mechanism is hit, this may be reduced to 0. While is it still possible to fight effectively without a functional turret by turning your hull, it is recommended that you find cover and wait for your crew to repair it. Turning to aim will often expose your weak spots to enemy fire and should only be done when absolutely necessary.
Technically, the Turret & Turret Ring are two different things, but in the game, they are counted as the same module. However, for the sake of this page, we'll keep them together.
Most tank destroyers do not have turrets.
The turret is the only module that when hit lowers the tank's main HP, and has a submodule, being the Turret Ring.
The turret ring is what allows the turrets to turn. If it's damaged, it slows your turret's turning speed, and even stops it completely when critically hit.
Sometimes, when a turreted tank is destroyed, its turret will detach from the tank in an explosion, also known as a Catastrophic Kill. This happens when a shell detonates the ammunition of a tank (also known as the ammo rack), causing the ammunition to blow. This creates such a force that rips the entire turret off of the tank. A hit from a larger gun seems to make the explosion more violent. There have been some cases where a light tank is traveling at full speed when it is destroyed, causing the turret to "fly" far from the tank's resting place.
Non-Researchable Modules
Fuel Tank(s)
A fuel tank provides the engine with fuel. Like engines, fuel tanks can catch fire when hit.
Ammo Rack
The ammo rack is where ammo is kept in a tank. If it gets damaged, your loading speed decreases, as your crew has to be careful when handling damaged shells. When it gets critically damaged, the ammo explodes. This is referred to as being "Ammo Racked", or simply "Racked".
This module is technically researchable as it is included with the gun. However, since it is a separate entity from the gun in battle and not researchable by itself, it is included here as a non-researchable module.
Sights
The sights are what allows your commander & gunner to spot and acquire targets. When this module gets damaged, it decreases your effective view range.
This module is technically researchable as it is included with the turret. However, since it is a separate entity from the turret in battle and not researchable by itself, it is included here as a non-researchable module.
Hidden Modules
Radios
The purpose of radios is unknown, but they nevertheless exist in the game files. Radios are the only module that cannot be damaged or destroyed, and thus have no hitbox in the tank model.