Hydraulic power transmission kinematic layout for railway vehicles

   The purpose of this study is to improve the efficiency of power transmissions used in railroad and other self-propelled vehicles. The project is intended to expand the functionality and improve the performance of torque converter-based hydro-mechanical transmissions. Hydrodynamic transmissions with fluid couplings and torque converters are extensively used in self-propelled vehicles due to their significant advantages. Analytical reports claim the global torque converter market will grow in the years to come. It shows a sustainable demand for torque converters used in vehicles. The key disadvantages of torque converters are insufficient efficiency as compared to mechanical transmissions, and limited auto torque range. There are some diesel locomotives with hydraulic transmissions in service. The reason is that hydraulic transmissions feature high traction, relatively low specific weight, and lower cost compared to electric transmissions, and do not require scarce copper. Shunting and mainline diesel locomotives use multi-loop hydraulic transmissions containing several hydrodynamic transmissions alternately switched as the diesel locomotive runs. The hydraulic transmissions are optimized for specific locomotive driving conditions. Despite all their advantages, multi-loop hydraulic transmissions are complicated, large, and heavy, while the switching is slow.   To overcome the disadvantages of multi-loop hydraulic transmissions we proposed new kinematics of a singlecirculation hydraulic transmission using a modified two-stage hydraulic torque converter with axial and inflow turbines. The torque converter controls to support the independent or joint operation of the turbines. The first axial turbine operates in the 0...0.6 gear ratio range, and the inflow turbines operate when the gear ratio exceeds 0.6. The torque converter also includes two reactors optimized for joint operation with the first or second turbine. To design the hydrodynamic transmission, we applied the theory of machines and mechanisms, and machine drives synthesis principles, and analyzed a wide range of existing designs, and basic and experimental research in hydrodynamic transmissions. The proposed solution makes hydrodynamic transmissions more compact and lighter than other similar designs. The proposed solution is patented in Russia.