## 6 Conclusions  
The main results of the conducted research are as follows:  
1. The development a really helpful practical method of designing spatial frames for road vehicles, even before the formation of design documentation, which allows structural changes to be made relatively easily, with a large number of iterations aimed at increasing the strength of the truss. This goal was achieved, thanks to the use of a combination of models made from beams instead of solid elements and the application of adequate boundary conditions; the calculation process in the Ansys Static Structural environment is minimal in terms of resource requirements and flexible enough to conduct dozens of consecutive analyzes by making changes to the design;
2. The basic calculation modes for \"bending\" and \"torsion\" are sufficient to comprehensively analyze the structure of the frame from the point of view of uniform strength and compliance with the strength conditions relative to the yield point. Taking into account the dynamic coefficient \(k_{d}=2.0\), the maximum stresses of the model were 381.13 MPa before optimization and 270.5 MPa as a result of the improvement measures. A significantly increased uniform strength was achieved based on the results of the map of the indicator \"safety factor\" and the mass was reduced by 4.13%;
3. The \"torsion\" mode, after the optimization measures had been implemented, did not reveal unacceptable values in terms of deformations that would make normal operation of the units impossible (the maximum values were 12.1-14.5 mm, depending on the side of the suspended wheel). The relative displacement of the corners of the windshield armhole did not exceed 10-15 mm, which allowed the glass to fit on the glue. The diagonal hanging mode was more dangerous (deformation over 30 mm), but the probability of such a situations was minimal; in addition, we are dealing with an electric powertrain, not an internal combustion engine, where there were tight tolerances on the relative movements of the transmission and engine;
4. The global conclusion is that the transition from internal combustion engines to electric units totally changes the rules of the game; you cannot install an electric powertrain behind the driver to house heavy batteries on a classic truck frame, especially for such a special purpose vehicle as a garbage truck, the resulting hybrid would have layout conflicts and would demonstrate its inefficiency. That is why the development of methods for analyzing the strength of spatial beam frames is a promising direction in modern science and engineering;
5. Considering how the space truss in a garbage truck differs conceptually from the classic spar frame in trucks and the stress and deformation results that were obtained as a result of the bending and torsion regime, it definitely makes sense to conduct further certification studies, particularly in regard to the UNECE R29 and NCAP (frontal impact), UNECE R66 (side rollover), and UNECE R100 (electric battery frame safety) rules.  
Conceptualization, K.H. and E.K.; methodology, K.H.; software, K.H., M.Z. and T.W.; validation, K.H., M.Z. and T.W.; formal analysis, O.B., V.R., R.H. and S.B.; investigation, O.B., V.R., Y.F., R.H. and S.B.; resources, O.D.; writing--original draft preparation, K.H. and O.D.; writing--review and editing, K.H., A.M. and T.W.; visualization, I.K. and Y.R.; supervision, K.H., I.K., E.K., M.Z., A.B., H.B. and A.M.; project administration, O.H. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
The data presented in this study are available on request from the corresponding author.  
The authors declare that there are no conflicts of interest.