## 4 Conclusions  
Based on the results of all the above tests, we can conclude the following:  
1. The tests generally confirmed the expected advantages of bolted friction joints, according to the solution described in patent no. PL 238010 B1. This also established the load capacity of the vertical bolted connection nodes in the faces and girders of light cranes (with the parameters listed in Table 1). Finally, this confirmed the possibility of using local machining on surfaces, connecting the nodes of flange plates or gusset plates (with the help of spacer-bearing machining rings to obtain complete contact between all load-bearing friction elements) without the need for machining of the entire plate surface. 2. Maintaining the geometric and mechanical parameters of spacer-bearing rings in innovative connectors--at least for those that are not inferior to those of the rings created for this research--is a fundamental condition for ensuring the effectiveness of \"whitening\" the surfaces of the connected elements. Maintaining these parameters also determines the real load capacity of innovative bolted connectors and the possibility of reducing the cost associated with forming connecting nodes in the load-bearing structures of light cranes with these connectors. This will make it possible to eliminate the need to machine (plan) the complete surfaces of connected elements (sheets) coming into contact with these nodes. Screw connection nodes containing innovative screw friction joints may have a load-bearing capacity 10% higher real load capacities than the calculated load capacities of comparable connection nodes, according to existing design solutions (e.g., the standards in [34; 35; 36; 37]). 3. Ensuring the required load-bearing capacity of these connectors also depends on due care in their manufacture, particularly in kneading down, which mainly refers to the spacer-bearing rings of these joints. Three repetitions in the assembly work conducted for the experimental load-bearing structures were sufficient to achieve stability in the bolt preload forces in the innovative connection nodes of these structures. Under the described control test conditions, this allowed them to carry loads that were not smaller than those that occur under real operating conditions for the relevant cranes. Obtaining higher load capacities is conditioned not only by the hardness and quality of execution of the rings, but also by the care taken in creating these rings. With the help of such rings, as well as careful implementation, elements that need to be joined can be \"whitened.\" These elements can also be \"whitened\" by overcooking them several times with the rings in individual innovative friction joints before the final tensioning of their bolts. 4. Given the results of this research, we would be justified in undertaking further in-depth, fundamental research using appropriate tools applied in the field of technical sciences. Regarding friction-shaped joints in the innovative bolt joints described herein, such research would reveal the influence of the following factors on the magnitude of the forces applied to these joints: bolt preload forces; the depth and shape of the tooth outlines of the working surfaces of spacer-bearing machining rings; and kneading down. 5. Until these results are recognized and implemented, the current provisions in relevant regulations and standards on the limits of friction joint coefficients should be applied when designing load-bearing superstructures for light overhead cranes with connecting nodes using the types described in this study. These current values should be used even though they are at least several percent smaller than the corresponding values resulting from our tests. In experimental load-bearing structures, it is advisable to make their prototype connection nodes in two ways; for example, with class 10.9 bolts (as in the above-described physical models of the nodes tested on the experimental bench) and class 12.9 bolts. 6.