How the USSR Studied the Leopard 2 Road Rollers

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How the USSR Studied the Leopard 2 Road Rollers

It is no secret that Soviet tank builders paid special attention to technological innovations, original design solutions and other technical nuances used in the production of Western tanks. tanks. And not only because awareness in this regard made it possible to evaluate certain qualities of foreign technology, but also because some ideas could be adopted and used in domestic production.

It is noteworthy that these ideas sometimes related, at first glance, to components of the tank that were completely insignificant in terms of the originality of the design idea. An example of this is the road wheels of the German Leopard 2 - strangely enough, domestic researchers also managed to thoroughly study them and even found a lot of useful things in their design, and what exactly - you can read in the report from 1988, which we publish here.




Features of the road wheels of the main tank "Leopard 2"


In foreign tank building, much attention is paid to improving the chassis, increasing its reliability, and improving volume-mass indicators. An example of this is the support roller of the West German tank "Leopard-2".

The predecessor of this tank, the Leopard 1, weighing 12 tons less with the same number of road wheels (14 units), used double-row road wheels with massive tires with a diameter of 660 mm and a rim width of 118 mm in combination with a rubberized track. The Leopard 2 tank, apparently in order to reduce costs, uses tracks with articulated tracks with a metal tread and a staggered overlap of the gap between the tracks. The diameter of the road wheel and the rim width of the disk of this tank are increased to 700 and 140 mm, respectively. In order to improve the interaction of the rubber tire of the road wheel with the metal tread of the track when the roller moves from track to track, the shape of the edge of the tread on the track has been changed.

Compared with the road wheels of the domestic T-80 and T-72 tanks, the massive tires of the Leopard 2 tank road wheels are 1,4–1,5 times smaller in height and 1,2–1,3 times smaller in width. The weight of the disk with the tire for the road wheels of the Leopard 2 tank is 46 kg, which is 20% less than that of domestic tanks. At the same time, the loading mode of the road wheels of the Leopard 2 tank is quite intense, as evidenced by the heating of the rubber massif during prolonged movement up to 200°C. The road wheel of the Leopard 2 tank is detachable and consists of two identical disks with tires. The road wheel disk (Fig. 1) is made of aluminum alloy and has a disc shape.

The disc shape is very technologically advanced and practically eliminates the possibility of soil accumulation in the roller opening. In the center of the disc there is a hole with a diameter of 205 mm for mounting on the hub and 8 evenly spaced around the circumference mounting holes with a diameter of 23 mm. In the area of ​​interaction with the track ridges on the inner side of the aluminum disc there is a wear-resistant coating on the annular surface with a width of ~75 mm, a thickness of 4 mm, having a color characteristic of oxidized iron.


Fig. 1. The disk of the support roller with a solid tire of the Leopard-2 tank: 1 - sections from the sprues of the rubber tire; 2 - holes for fastening the disk to the hub

In the cross-section of the disk (Fig. 2), the interface between this coating and the base metal has a saw-tooth profile (relief) with triangular teeth - their pitch and depth are 1,5 mm. The wear-resistant coating is also applied to the edge of the disk, beveled at an angle of 45° at the transition from the flat end surface to the surface of the disk rim, which ensures that the outer edge of the wear-resistant layer is covered by an overhanging tongue of the rubber mass. This is necessary to exclude direct impact on the end of the coating of the track ridges. On the outer sidewall of the tire, protruding bosses are visible along its entire circumference, which are probably the remains of cut sprues (see Fig. 1).

In terms of chemical composition, the main material of the support roller disc is an aluminum-based alloy, alloyed with copper, magnesium, manganese and silicon (Table 1).

The closest domestic analogue is the deformable aluminum alloy of the AK-8 brand. The mechanical properties of the disk material in terms of relative elongation differ significantly in samples cut from the rim (1,2...5,6%) and hub (6,8...10,4%). Similar values ​​have the relative elongation of the AK-8 alloy in samples cut across the grain (3%) and along it (8%).


Fig. 2. Cross-section of the disk with the tire of the support roller of the Leopard-2 tank: 1 - disk; 2 - wear-resistant layer; 3 - solid tire

Analysis of the macro- and microstructure of the disk material showed that it was manufactured by hot volume stamping from an original cast blank. When cutting the disk with cutters made of P18 grade tool steel, the wear-resistant layer crumbled in the form of a black powder with shiny metal inclusions; significant wear of the cutting tool was observed.


Table 1. Chemical composition of the support roller disk of the Leopard 2 tank, % by weight

The wear-resistant layer is close in composition to steel containing 0,3...0,5% carbon, alloyed with 12% chromium and having 5% oxygen (Table 2). The hardness of this layer at the surface is 40...41 HRC. The adhesion strength to the layer tearing off from the base material of the disk is 4 MPa.

The microstructure of the wear-resistant layer contains gray and white phases and pores. Micro-X-ray spectral analysis has established that the white phase is steel alloyed with chromium (8...12%). The gray phase, in addition to iron and chromium, contains 25...30% oxygen, i.e. it is a complex oxide of the spinel type (Fe, Cr)n Оm. The microhardness of different phases of the wear-resistant coating varies from 3500...4500 to 5700...6500 MPa.


Table 2. Chemical composition of the wear-resistant layer for the support roller disk of the Leopard-2 tank, % by weight

The high content of oxygen and nitrogen in the coating in the form of supersaturated solutions is apparently caused by saturation with gases during the spraying process during the interaction of these particles with the atmosphere and working gases at high particle cooling rates. The microsections show a layered structure (Fig. 3) resulting from strong deformation and rapid crystallization of the sprayed particles. The connection of the wear-resistant layer with the base material of the roller disk is tight, with a clearly defined boundary. In some places, incomplete adhesion of the layer to the base material with a width of 2–4 μm is observed. No signs of the presence of glue and other binders at the boundary or diffuse bonding of the layer with aluminum were found. According to preliminary estimates, the wear resistance of the coating material is not lower than the wear resistance of steels used to manufacture the flanges of the support rollers of domestic VGMs (usually steel grade 38ХС with bulk hardening).


Fig. 3. The structure of the connection of the wear-resistant layer (1) and the disk metal (2) at a multiplicity of 100

Thus, the wear-resistant layer is a powder material consisting of 70...75% steel, close in composition to grade 30X13 steel, and 25...30% spinel-type oxide. It can be assumed that the coating was obtained by plasma or arc spraying of two types of powders (steel and oxide) onto the corrugated surface of a rotating disk.

It has been noted in foreign literature that the destruction of the coating applied by various spraying methods to aluminum disks of support rollers, in turn, causes the destruction of the rubber mass of tires. Options for solving this problem are being considered, in particular, by replacing the wear-resistant layer with a pressed steel flange. This indicates that with all the advantages of using a wear-resistant coating on aluminum disks of rollers (reduced roller weight, manufacturability, better interaction with track ridges), this solution requires careful development and testing in a wide range of operating conditions.

Studies of the rubber mass of the tires showed that it is made on the basis of butadiene-styrene rubber (the domestic analogue is oil-filled rubber of the SKS-30ARKM-15 type) and is characterized by a high content of softener. In terms of physical and mechanical properties, this rubber is close to the domestic 4E-1386 and surpasses the 34RI-14 rubber. Unlike domestic solid tires, the West German tire is made by injection molding or injection molding. Vulcanization of the rubber is carried out using sulfur - zinc oxide was used as an activator. The rubber mass is attached to the rim using glue.

An analysis of the design and technological features of the road wheel of the Leopard 2 tank showed the feasibility of studying the possibility of using two technical solutions for road wheels in domestic tank building:

1. A wear-resistant coating on aluminum disks, applied by spraying instead of steel flanges, allows to reduce the weight of the support roller by 5...6%, reduce the labor intensity of its manufacture and improve the interaction of the roller with the track ridges.

2. The casting method for manufacturing solid tires from high-strength rubber increases the homogeneity of the rubber mass structure and the stability of the tire manufacturing quality, and consequently, the service life of the support rollers as a whole.

Source:
"Features of the road wheels of the main tank "Leopard 2"". V. A. Varchev, B. V. Gladkikh, Yu. N. Istomin, G. M. Tereshchenko
23 comments
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  1. BAI
    0
    14 January 2025 06: 04
    staggered overlap of the gap between the tracks.

    A worthy successor to the Tiger
    1. -1
      14 January 2025 06: 07
      Quote: BAI
      A worthy successor to the Tiger
      I remember during the war, German tankers were even teased with these "chess rollers" wink
      1. 0
        14 January 2025 09: 51
        I remember during the war, German tankers were even teased with these "chess rollers"

        The staggered arrangement allowed to increase the number of rollers and reduce the load on the rubber bandage, and accordingly increase the service life of the rollers and tracks.
        1. +6
          14 January 2025 10: 15
          What do rollers have to do with it? We're talking about tracks.
        2. +3
          14 January 2025 10: 34
          The staggered arrangement allowed to increase the number of rollers and reduce the load on the rubber bandage
          The staggered arrangement seriously complicated maintenance and repair of the tank, especially in field conditions...
        3. +4
          14 January 2025 10: 41
          And it was also patented by the head of the 6th department, Mr. Knimpkamp, ​​and, lo and behold, only tanks with a checkerboard arrangement went into production.
        4. -1
          28 January 2025 16: 10
          And when clogged with mud, they took off their shoes... and in winter they simply froze... Well, and repairs... that's brutal... By the way, ours also take off their shoes... T-64 is the leader and T-80 in severe contamination... T72 is the best in this matter... but the rubber bandages are destroyed by angular impacts.
      2. +6
        14 January 2025 10: 07
        I don't know if they were teasing them or not, but replacing or repairing such rollers in field conditions, and possibly under fire, was quite a job. But the ride was smooth, which affected the results of shooting on the move. Subsequently, they abandoned the staggered arrangement of rollers due to the more difficult maintenance.
  2. +5
    14 January 2025 07: 22
    The chassis is very important not only for the convenience of using the tank, it should provide a smooth ride on any soil, this provides better stabilization when shooting and at the right moment it can play as intended. The smaller the rollers and the more of them, the softer and smoother the relief flow.
  3. +3
    14 January 2025 09: 46
    Very interesting.
    In general, now in Russia it is necessary to create an easily accessible base of technologies for the production of basic parts - gears, axles, etc.
    1. +9
      14 January 2025 10: 16
      This entire base has existed for a long time. The issue is not the base, but the colonial administration.
  4. +2
    14 January 2025 11: 47
    Did they steal the whole "kitty" or did they roll the steamroller away?
  5. +2
    14 January 2025 12: 55
    The Germans are talking about replacing spraying with steel pressing, and ours are talking about replacing pressing with spraying ))))
  6. +2
    14 January 2025 14: 55
    A very interesting article for me, from the point of view of materials science and technology. Thank you.
  7. +1
    14 January 2025 21: 33
    As I understand it, first you need to calculate the load on the disk and then compare the mass-strength characteristics and wear resistance.
  8. +1
    15 January 2025 00: 02
    Our people could cast titanium rollers instead of selling titanium products to Boeing.
    They would be better in all respects than both aluminum and steel, and no coatings, sprays or other crap are needed.
  9. +1
    15 January 2025 00: 53
    and the Germans use glue to attach the bandage...like everyone else. If the rubber has a high softener content, injection molding is more likely. Spraying is an interesting thing...but the Germans themselves don't like the result. Should we rush to repeat their mistake?
    1. kig
      -1
      15 January 2025 10: 56
      Quote from moneron
      shall we rush to repeat their mistake?
      this text is from 1988, all the mistakes have already been repeated
      1. -2
        15 January 2025 14: 37
        Quote: kig
        this text is from 1988, all the mistakes have already been repeated

        After the "mistake" (read as "betrayal") of 1990-1991, everything else fades into obscurity.
  10. +1
    15 January 2025 13: 53
    Oh how I love such a meticulous analysis with details! Thank you author!
  11. 0
    15 January 2025 19: 08
    German glue solved...
  12. -1
    18 January 2025 10: 54
    The plate-type chassis of the Tiger and Panther really did provide good bonuses to the smoothness of the ride and gun aiming. There is also an opinion that the Panthers could shoot on the move, but at low speed. Alas, the T-34 and T-34-85 did not have such an advantage, they had to stop (which is like death) due to the lack of a stabilizer. But due to the vagaries of the Panther's chassis and transmission, which are prone to overheating, shooting on the move was prohibited.
    1. -1
      20 January 2025 16: 05
      They outshot the USSR tanks in terms of range and penetration