In 2006, Uralvagonzavod first showed the new T-72B2 tank, which differed from the previous family vehicles in a number of innovations. One of the main features of the new combat vehicle was the upgraded 2A46M-5 cannon. This weapon with the ability to launch guided missiles is a further development of the 2A46 family of weapons and differs from older guns in a number of design features and related characteristics. According to the official information of the Yekaterinburg "Plant No. 9", which created the 2A46M-5 gun, the use of new technical solutions made it possible to significantly increase its characteristics and ensure superiority over other weapons of the family.
It should be noted that the designers of "Plant No. 9" simultaneously developed two new modifications of the 2A46M gun: 2A46M-5 and 2A46M-4. These guns have several differences due to their purpose. The 2A46M-5 gun was proposed to be installed on the upgraded T-72 and T-90 tanks, and the 2A46M-4 was intended to equip the T-80 vehicles. The most noticeable difference between these guns is the different design of the left fence. The fencing of the 2A46M-5 gun was developed taking into account the use of the "Tagil" automatic loader, and the fencing of the 2A46M-4 is compatible with the loading mechanism of the T-80 tank. All other units and assemblies of implements are unified. Due to the minimal differences, we will further consider both guns using the example of 2A46M-5.
The new tank guns of both models are modernized versions of the previous guns of the family, developed using several new ideas. The main methods for achieving higher characteristics were increasing the rigidity of the cantilever part of the barrel, improving the dynamic balance of the gun, tighter tolerances in the manufacture of the barrel and an updated system of fastening the barrel in the cradle.
The 2A46M-5 cannon can be mounted on the same mounting systems as the 2A46M. The 2A46M-4, in turn, is interchangeable with the 2A46M-1 at its mounting location. The most noticeable external difference between the updated guns is the barrel bend counting device. The device itself is installed above the breech of the barrel, and a reflector is attached near the muzzle. The bend meter detects the deviation of the barrel axis from the neutral position and sends this data to the fire control system. The use of data on barrel bending in the calculations allows to increase the accuracy during intensive shooting and to compensate for the deformation of the barrel tube caused by heating.
During the modernization, the gun cradle has undergone major changes. So, to reduce the cantilever of the barrel, it was proposed to use a cradle with a neck extended by 160 mm. The modified throat has greater rigidity in comparison with the parts of the previous guns of the family. In addition, a second prismatic bushing made of bronze is used in the construction of the cradle.
In the 2A46M-5 / 2A46M-4 project, the barrel geometry tolerances have been reduced. However, in the manufacture of tools, backlash may occur when the barrel is installed in the cradle. For a tight fit of the trunk in the cradle, the latter is equipped with two backlash-selecting devices, in the front and rear of the upper surface. Each of these devices includes two bushings with rollers, placed in special shafts in the cradle and pressed with screw plugs. Four rollers reliably press the barrel against the lower inner surface of the cradle and get rid of backlash.
The design of the supports for the retractable parts of the gun has been changed. The front support consists of two bronze annular bushings, the back one consists of four rectangular overlays of the same material. The rear support has been moved to the carrier part of the cradle. Such improvements made it possible to improve the fixation of the barrel on the supports, as well as to eliminate the overturning moment during rollback.
The cradle of the 2A46M-5 gun is equipped with new devices for mounting in the tank. In particular, new backlash-free trunnion bearings with hollow rollers with an elastic surface are used. Such bearings reduce the backlash when installing the gun, and also improve the fixation of the trunnions in the turret of the armored vehicle.
Like the previous armament of the family, the 2A46M-5 gun is equipped with a smooth 125 mm barrel, 6 m long. The length of the charging chamber is 840 mm. To improve the accuracy of shooting, the modernized guns received a barrel manufactured with smaller tolerances. During the development of the project and production technologies, it was possible to optimize the geometry of the barrel while maintaining the required characteristics. So, the stiffness of the trunk pipe increased by 10% to 420 kg / cm. In addition, the difference in wall thickness of the muzzle of the barrel at a length of 1 m has been reduced. At the request of the customer, the barrel bore can be chrome-plated, which increases its resource.
To simplify maintenance, the barrel of the 2A46M-5 gun is attached to the breech using a bayonet connection. When dismantling the barrel, you need to put on a special key on its octagonal part, turn the barrel 45 ° and squeeze it out of the breech. Using a crane with a lifting capacity of up to 2 tons, the repair department can replace the barrel in about 4 hours. Dismantling the turret is not required, which is a characteristic feature of the guns of the 2A46M family.
During rollback, an overturning moment acts on the gun barrel. To reduce it, the design of the 2A46M-5 cannon used recoil devices with a diagonal arrangement of recoil brakes. One of them is located in the upper right (when viewed from the breech of the gun) part of the breech, the second is in the lower left. A knurler is provided to the right of the lower brake. All hydraulic components of the implement are equipped with visual monitoring devices for the amount of fluid.
The purpose of projects 2A46M-5 / 2A46M-4 was to improve the characteristics of fire. The main characteristics, such as the firing range or the power of the ammunition, remained the same or depend on the type of projectile used. At the same time, the accuracy characteristics have significantly increased. In comparison with the 2A46M gun, the accuracy of fire is increased by 17-20%. The total dispersion when firing in motion is reduced by 1, 7 times.
The 2A46M-5 and 2A46M-4 guns can use the entire range of 125mm ammunition for the 2A46 family guns. In addition, they can be used as a launcher for the Cobra and Reflex guided missiles. Improving the characteristics of the gun allows you to increase the effectiveness of fire, even when using existing ammunition.
The 2A46M-5 and 2A46M-4 cannons are intended for installation on tanks of the T-72, T-90 and T-80 families. Provided the ability to mount guns not only on new combat vehicles, but also on existing equipment in the course of its repair and modernization. According to some reports, in 2006-2007, the upgraded 2A46M-5 / 2A46M-4 gun was adopted by the Russian army and installed on new tanks.
