## 4. Constructional and Functional Aspects of Chains  
### Types, Materials, and Applications  
Chains can be classified according to their type (construction), material, and intended application. The classification presented in Figure 4 was developed based on the authors' expertise and an extensive literature base [1, 33, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64]. Figure 4. _Cont._  
In technical applications, three main types of chains are most commonly used: ring (link) chains, ladder chains, and plate chains. Ring chains (Figure 5a) have such a wide range of applications that it is impossible to list them all comprehensively. In the maritime industry, they are used for anchoring, mooring vessels, and securing cargo on deck. In construction, they serve as load-bearing elements for lifting and moving heavy structures, as well as for securing scaffolding. In mining and extractive industries, these chains are employed for transporting raw materials, anchoring mining equipment, and stabilizing structural components. In transport and logistics, they are used to secure cargo during transit and in warehouse loading and unloading systems. In agriculture, livestock farming, and forestry, chains are used for towing, stabilizing, and other high-strength operations. In the energy and petroleum sectors, they are applied in handling drilling equipment, pipe transport on platforms, and underwater installations. The entertainment industry uses ring chains for suspending heavy stage components, such as lighting and rigging systems. Outside of industry, they are also widely used in daily life, for example, to secure gates, doors, or vehicles against theft. In all these cases, proper material selection, chain strength, and corrosion resistance are critical to ensuring durability and reliability under varying operational conditions. Figure 4: Classification of chains according to (**a**) type, (**b**) material, and (**c**) application. Figure 5: Basic types of chains: ring chains (**a**), ladder chains (**b**), and plate chains (**c**). Ladder chains (Figure 5b), including pin, roller, and bushing types, are primarily used as tensile elements in chain drives. In mechanical and manufacturing industries, they are widely used in drive systems where they enable effective transmission of force and motion. Their construction provides increased stability and precision in power transmission, which is crucial for high-performance machines such as presses and assembly lines. Plate chains (Figure 5c) are mainly used as load-bearing tension members in the construction of trolley systems. A specific variant of the plate chain is the cutting chain, used in devices such as chainsaws. Chains designed for lifting (e.g., when used with a hoist), pulling, or securing (e.g., in bicycle locks) typically have toroidal links, enabling movement in two directions. Chains used in power transmission within machinery have specially shaped links that mesh with sprockets and are designed to articulate in a single direction only. Delicate chains made of precious metals, in which links often take on complex and refined forms, are popular jewelry products. Small chains used as personal adornment are generally decorative counterparts of the technical chain types described above. Various engineering materials are used in the production of chains [15]. Material selection plays a critical role in ensuring durability, operational efficiency, and resistance to specific environmental conditions. The choice of material depends on application-specific requirements, such as load-bearing capacity, operating environment, and usage conditions. Technological advancements in the chain industry have significantly influenced material choices, leading to improved performance and greater environmental sustainability. Stainless steel remains one of the most commonly used materials. It is characterized by excellent corrosion resistance, making it ideal for humid environments or those involving chemical exposure.