Tank’s modules have their own hitpoints although they are not displayed anywhere in the GUI. When a round hits a module, the game calculates the damage and applies it to the module. If the damage is not enough to break the module, the module’s hitpoints are decreased and the shooter hears only a “ding!” sound without the game saying “Critical hit”. The affected module will be displayed in orange-ish (or yellow, depends how you look at it :)).
BTW, sometimes, when you hit, for example, a side of a track, and the round doesn’t penetrate through the track AND the hull, you only hear a ding but the enemy’s hps don’t go down and he continues driving. This is because you only decreased the track’s hps, which are separate from the tank’s hps.
If the damage is enought to break the module, the shooter hears a ding, the game says “Critical Hit” and the module goes red. After awhile (depending on your crew’s percentages, their Repair skill as well as on whether you have a Toolbox installed), the module is repaired and it’s functional again but only partially (gun’s accuracy is worse, turret rotates slower, engine is slower, etc.). Some of the module’s hps are restored but obviously not to the full. Unfortunately, the game displays such modules with the same color as the slightly damaged ones (orange-ish/yellow), so AFAIK you can’t tell, just by looking at them, which ones have their performance reduced and which ones were just slightly damaged.
Obviously, the repaired modules are easier to break again.
When you fire at the enemy and hear “critical hit”, you don’t really know for sure what exactly you broke. Often you can tell by observing the enemy - tracks fall off (duh), tanks slows down - engine, enemy doesn’t shoot for a long while - gun, enemy takes longer to reload - ammo box or the loader.
BTW everything above also applies to crew members, only those don’t come back to life on their own.
Most people I know tend to bring consumables with them. That’s why sometimes you see an enemy lose his track and then get it back up within a second. I tend to use consumables when the damage affects my combat abilities - accuracy, loading times. Although there are situations where you really don’t want to be sitting and waiting for your track to be repaired automatically.
IMO consumables are very helpful and, at higher tiers, they are totally worth it. They cost 3K but they also allow you to live longer and fight better thus allowing you to get more credits (and exp) as a result.
