MIE.33 – Hydrostatic Transmission

• Bilal Nasir
• Martin Quiroz
• Daniel Rasmussen
• Rishik Sreepati Panditaradhyula

The UIC SAE Baja team designs and builds an offroad car far the SAE Baja competition. Starting in 2023 the rules will be updated to require that every car is four-wheel drive. This project is to design a hydrostatic transmission as an alternative to the traditional continuous variable transmission that is currently used and validate the design using ANSYS simulations. The design that was finalized includes a main pump with a swash plate that is controlled by a push pull cable and four separate driven wheel pumps that are connected in series with reinforced hosing. Other design choices that were briefly explored include: having a two axle system where the front wheels are linked and the back wheels are linked, using a simple bar linkage to control the swash plate, and using different materials for the fluid lines. This project does not include the production of a prototype, so all designs were validated using ANSYS simulations. The pumps were subjected to Fluent simulations to analyze the fluid flow and the resulting pressures were exported to a static structural simulation to determine part deformations and safety factor. The swash plate was subjected to a static structural simulation to determine deformation due to the forces applied by the main pump and the safety factor. All simulations were performed with a variety of different configurations of flow rate and engine speed to account for the changing conditions of the system. The two materials that were considered for manufactured parts were structural steel and aluminum 6061 T6. The results yielded by simulations confirmed that the system would not fail under maximum load for either material, so aluminum 6061 T6 was chosen as the material for production. The design is successful at accomplishing the goals of the project because it fulfills the requirements of the sponsor and is able to reach a competitive speed of over thirty miles per hour.