there are a few tank designs that just look sort of odd for example the French AMX 13. that's because the AMX 13 uses what is known as an oscillating turret the turret itself is split into two parts one for rotation and one for elevation in this video I'll walk you through the design how it works the advantages the disadvantages and the Fatal flaw that meant that this type of turret has no real place on the modern Battlefield conventional tank turrets work as follows the turret is mounted on a turret ring which is set into the hull of the vehicle the turret can rotate 360 degrees in this ring the gun is mounted onto the front of the turret in such a way that it can pivot up and down rotating around the mounting point this means that the gun can be pointed in any direction by rotating the turret and can be elevated or depressed in order to aim at something above or below the tank this has been a system used on the vast majority of armored fighting vehicles from the ft-17 to the M1 Abrams an oscillating turret achieves rotation and elevation in a very different way firstly the turret itself is split into two parts the lower turret sometimes called the color works the same as a conventional one it engages with the turret ring and can spin 360 Degrees providing the rotation the upper turret contains the entire gun and importantly the gun is fixed to this upper turret and cannot Elevate or depress on its own instead in the gun the entire upper turret pivots up and down rotating around trunion set into the lower turret but this seems quite complicated right right but it does have some pretty huge advantages firstly it means the turret ring can be smaller you have to remember that the visible gun poking out of the tank is only part of the assembly inside the turret you have the large blocky gun breach that the loader puts the shells into so when the gun is elevated I.E pointing up the breach drops down and in a conventional turret the turret ring has to be large enough to allow the breach to drop through on an oscillating turret this is no issue when the upper turret pivots to elevate the gun the pivot point is much farther back meaning the breach drops a smaller distance and so you can get away with a smaller turret ring and by extension a smaller turret the terroring diameter is also a huge driver in how wide a vehicle has to be so using an oscillating turret means you can ride a big gun on a small tank as is the case with the AMX 13. when a conventional turret aims upward or elevates the gun the breach sinks down into the turret ring if the Gunner aims down or depresses the gun the bridge Rises and The Gun depression of the vehicle is usually limited by how far the bridge can rise before it hits the roof of the turret gun depression is an incredibly important feature as vehicles with more gun depression can expose a lot less of their tank when shooting over Hills and other Terrain Again by mounting the gun rigid inside the upper turret oscillating turret Vehicles don't have this issue and usually have quite good gun depression as a result limited more by physical features such as the shape of the lower part of the turret or the gun hitting the hull of the tank itself in terms of gun depression and elevation though these vehicles do have a disadvantage the breach may not hit the turret ring but the rear of the turret itself can hit the engine deck when elevating the gun you can see this clearly on the AMX 13. the gun can't actually Elevate all that much because the turret bustle would strike the rear of the hull to combat this and maximize elevation and depression oscillating turrets try to mount the gun as high as possible in the upper turret this comes with its own pros and cons it means the vehicle can peek over obstacles and expose very little of the turret but it means oscillating turrets tend to be quite tall like you can see in the AMX 50. the other major advantage of the oscillating turret design concerns loading the gun the loader is inside this upper turret and so he is moving along with the gun meaning the breach is in the same relative position to him at all times but the real kicker is when you want to fit your vehicle with an auto loader the autoloader is a device that automatically takes rhymes from the ammunition stowage and rounds them into the gun breach and this works fine in conventional turrets as long as the gun is completely level at zero degrees elevation or what is known as the index position but when the gun is elevated away from this index position the auto loader can struggle conventional turrets can solve this in two ways either use a more complex autoloader that can load the gun at any elevation or simply bring the gun back down to the index position between every shot the first option is expensive and the second isn't ideal aiming you've gone away from your target after firing is a huge disadvantage for obvious reasons an oscillating turret provides a neat solution as the autoloader mounted in the upper turret will be in line with the breach at all times so a vehicle with an oscillating turret and the autoloader can be small fast and pack a big punch but there is a catch splitting the turret into two as we discussed comes with a lot of advantages but there is one major disadvantage there's a gap between these two parts this means that vehicles with oscillating turrets are almost impossible to seal against the elements against water and critically against NBC threats NBC stands for nuclear biological chemical and almost every time today is fully protected against these threats through excellent ceiling and state-of-the-art air conditioning and filtration systems oscillating terrorists just cannot be sealed to the same level as some sort of Gap is required between its building parts for them to actually function properly this means that it's subjected to a gas attack or exposed to nuclear fallout the vehicle's Crews would be incredibly vulnerable and at the end of the day it doesn't matter how good your vehicle is if your entire crew is incapacitated the oscillating turret had its golden age in the 50s 60s and 70s spearheaded by French designs like the AMX 13 panhard EBR and amx50 many countries created their own oscillating turret vehicles with few actually entering service however an oscillating turret vehicle did enter service to the US Army in 2007 the m1128 striker mobile gun system or MGS the MGs features an unmanned 105 millimeter armed oscillating turret with its own Auto loader in theory this design would have all the benefits of an oscillating turret with none of the drawbacks as all of the crew is in the fully NBC protected Hull in this case it was not to be the vehicle's autoloader had a large number of issues and the entire system was just too expensive to be worth it so while oscillating turrets may not be cutting edge or even that relevant anymore it was an interesting idea that certainly had its advantages at the time and the look of those 60s and 70s oscillators is just so iconic and so space-age if you have an idea for what I should explain the next please do leave it down in the comments or feel free to put it in the Discord as always if you enjoyed the video leave a like and if you want to see some more do consider subscribing I'll see in the next one