In order to analyze the efficiency of a high-speed tracked vehicle powertrain, it is necessary to understand the powertrain workloads in specific working regimes. Experimental tests are conducted on a specific high-speed tracked vehicle, in various terrain conditions, in order to obtain accurate workload data and isolate the maximum workload regimes. From the power balance point of view, the most demanding working regime is the vehicle turning process, so corresponding test results are analyzed with special attention. The obtained results indicate that the slip of the turning mechanism friction elements greatly influences the character of the power balance change.

Unlike independent steering systems on wheeled vehicles, the steering mechanism on high-speed tracked vehicles are integrated in the power train system, therefore turning process consumes more engine power than straight driving scenario. To ensure the most efficient turning performance, power trains of high speed tracked vehicles are equipped with complex turning mechanism components which are, most frequently, mechanical or hydrostatic. In most cases mechanical components enable turning process by slipping of the clutches and other frictional components, which is inconvenient from the aspect of power balance, as well as from the performance aspect. On the other hand, hydrostatic components have low efficiency in certain working ranges. Modernization of the conventional mechanical systems by applying electric drive components can contribute to solving the mentioned downsides, given the fact that modern electric drive systems can have very sensitive torque and speed regulation which significantly improves electric drive performance. Applying these electric drives in auxiliary power flow ensures additional flexibility and the possibility for the power train to work in different working regimes, such as energy regeneration, which improves the power train efficiency. This paper includes a variety of possible hybrid power trains for high-speed tracked combat vehicles and a fully developed simulation model of a hybrid drive for power trains with two power flows (main and auxiliary). The simulation model provides the possibility to observe the quantified influence of the certain parameter change in the turning process and allows us to identify the important parameters for power train control during the turning process.

Introduction/purpose: The hydraulic buffering valve has the greatest influence on the dynamic characteristics of power-shift transmission. The hydraulic buffering valve is a transmission element that controls increase in pressure in friction assemblies during the gear shifting process. By choosing the optimal control of pressure increase during shifting, reduction of dynamic loads in gear transmissions and thermal loads in friction assemblies is achieved. Methods: The paper analyzes the principle of one of hydraulic buffering valve solutions as well as the influence of certain parameters on the control of pressure increase. After the analysis of the working principle of the hydraulic buffering valve, a simulation model was developed in the MATLAB/Simulink software package. Results: The results obtained using the simulation model were compared with the experimental results of the selected pressure modulator solution. The selected hydraulic buffering valve was developed as part of the development of a device for power-shift transmission. The simulation results showed a satisfactory match with the experimental results. Conclusion: The developed simulation model enables a relatively easy and quick change of the parameters of the hydraulic buffering valve as well as a possibility of a faster and better understanding of the influence of individual parameters on pressure increase during the gear shifting process.