The quieter you go, the further you go: tank suspension
Until the beginning of the 1912th century, a reliable chassis for combat vehicles simply did not exist. In XNUMX, the Holt crawler tractor appeared exclusively for civilian purposes. It was his chassis that was used as a model for the creation of the first tanks. However, soon the paths of engineering thought in different countries diverged. The British put a Holt undercarriage on their Little Willia, but were unhappy with the cross-country ability and, as a result, completely changed the suspension. The road wheels were rigidly fixed to the body, and the track was launched along its perimeter. The scheme was used on all diamond-shaped tanks and provided good maneuverability. The only caveat was that the crew was shaking mercilessly, but this did not prevent the design from being used until the end of the First World War. Meanwhile, the designers of the Renault FT have tried to soften the shaking. The suspension block of this machine was rigidly attached to the rear of the body, and shock absorbers were installed in front. This suspension was called semi-rigid.
The Germans and the French also worked with a slightly altered Holt chassis, but by the end of the 1920s it was finally clear that it would be impossible to create a full-fledged modern tank on a tractor chassis. It could no longer cope with the requirements for speed, cross-country ability and smoothness. Soon the American engineer W. Christie came up with his own type of suspension. It consisted of large-diameter rollers (each of which was sprung with a separate spiral spring) and was located vertically in a special shaft in the tank hull. Thanks to this solution, tanks could move both on tracks and on wheels to save resources. To do this, the tracks were removed, and the mechanic installed the steering wheel and drove almost like an ordinary driver.
Christie's suspension was also used on the Soviet T-34 tank. In order to reduce the height of its body and increase survivability, the springs were positioned at an angle. A similar chassis was installed on the Soviet BT, as well as on the British "Crusaders", "Cromwells" and "Comets".
At the same time, the French tanks "Saint-Chamond", "Schneider" and German A7Vs used a locked suspension. In it, several rollers (2,3 or 4) were located in a row and combined into a cart, which, in turn, was connected to the body by a common spring. The main advantages of this design were ease of manufacture, high maintainability and smooth running at low speeds.
Another type of suspension is French scissors. It is considered simple and "soft", and got its name because of its widespread use on military vehicles in France. The spring is spring-loaded, and there are two rollers in the trolley.
The British Vickers 6-ton tank also has a unique suspension. It features 4 rollers on one bogie and leaf springs, which made life easier for the gunners. The same type was used on the Soviet T-26 tank.
One of the reasons for the popularity of tanks on a locked suspension is their low sway. After all, the more rollers in the cart, the higher the smoothness of the ride. In the 1920s, designers experimented with machines and combined all rollers into one cart. But soon the idea was abandoned and they began to make a choice in favor of increasing the number of carts to increase the maximum speed.
The locked suspension was perhaps the most common during the Second World War, but it also has its drawbacks in the form of too vulnerable nodes, sloths and springs. They are located outside the tank, which means they need protection. To do this, the designers covered them with armor (for example, on Matilda and T-28 tanks) or placed them as low as possible, leading them out of the firing zone (this is how the T-26 works).
The concept of using tanks in the Soviet army of the 1930s provided for various uses of the vehicles in service. T-28s broke through enemy defenses, T-35s strengthened them, suppressing defense nodes and fending off tank counterattacks, T-26, meanwhile, helped the infantry to break through the front line. Tanks with a blocked suspension were engaged in breaking into the enemy's defense, and after them BT entered the breakthrough. Their task was to break out into the operational space and build on their success. Here the speed was needed, which was provided by the independent suspension. It is worth noting that tanks with such a suspension rocked heavily on the move.
To save the crew from shaking, the British successfully used hydraulic shock absorbers. Meanwhile, not every country managed to establish the production of these units, so the German designers abandoned the Christie suspension and first applied individual suspension of the rollers on their Pz.Kpfw. II, and then began to use a torsion bar chassis. However, there were some pitfalls. For its manufacture, high-quality steel was needed, and if the torsion bar broke, it was necessary to carry out complex repair work.
There was also a torsion bar suspension on Soviet cars. It was used both on heavy KV tanks and on light T-50 and amphibious T-40s. Also in those years, combined types of pendants were used. For example, a Porsche chassis was installed on the Ferdinand self-propelled gun. It had torsion bars and rubber cushions, and every two adjacent rollers were combined into carts (3 units on each side).
Another significant German invention is the staggered roller suspension. It was created by engineer Heinrich Kniepkamp in the early 1930s. A large number of rollers reduced the load on each of them separately, which ensured a smooth ride and increased shooting accuracy. This suspension was bulky, heavy, not very durable, and extremely difficult to repair. As a result, even the Germans abandoned it after the Second World War.
For more details on running combat vehicles, see the video from Wargaming.
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