Closed chains, chain nets, snow chains, protective tire chains, and other chain systems are not adjustable in terms of length and width (in the case of grid or ladder chains) unless the chain is opened and/or individual chain links are opened in order to remove or add chain links. The same applies for jewelry chains.
Many variants for connecting the last links in a finite chain by way of a special connecting element are also known in the art. Such a connection becomes necessary most frequently when chains break; for example, breaks on snow chains of motor vehicles or on protective tire chains of utility vehicles operating in stone quarries and similar environments. The problem that emerges when two ends of a broken chain must be connected is the fact that, most of the time, no suitable tools are available on site where the break occurred in order to install a regular chain link that was cut open for that purpose and must be welded closed again after having been inserted. Welding on the wheel is generally not possible because this may cause damage to the tire. Any removal of the chain armor from protective chains is extremely complex and creates, moreover, costs associated with the disruption of operations during the disassembly, repair work, and new installation.
Accordingly, repair chain links are already known in the prior art that can be connected to the links of the broken chain right on the vehicle. The repair chain links are often comprised of a ring with an overlapping thread that extends over a certain area in the way of a helical line. Chain links of this type can be inserted directly on the wheel into the outermost-lying chain links and then pressed together with the assistance of a strong pair of pliers. Also known are, furthermore, repair links that feature an (open) C-form; the only way to guide them around the neighboring chain links is with a pair of pliers, and then they must be bent in a backward direction. Reconnecting a broken chain without the use of tools is not possible with any of the known prior art repair links. Moreover, the repair links are usually only a short-term solution because, since they must be bendable after installation, they may not be manufactured of a hardened material. At a later time they must be replaced at a repair shop with other durable links. This requires additional expense.