The University of Waterloo Society of Automotive Engineers (SAE) Baja student team designs, builds and competes with a single-seat off-road vehicle, Figure 1, in the international Baja SAE competition. Over three days at the competition, the vehicle is put through a series of challenges, including hill climb, rock crawl, and an endurance race, and is evaluated based on its performance. Each year, the team produces a new design to address shortcomings observed in previous iterations. For the last six years, the team has experienced poor reliability and performance from the chain drive connecting the continuously variable transmission (CVT) to the wheels. Issues include broken sprockets, chain skipping upon deceleration, and premature wear of tensioners. In an effort to address these issues in the 2013 vehicle design, the UW Baja team considered developing a new drivetrain. The objective was to eliminate the use of chains in the driveline without affecting the vehicle geometry or adding significant additional weight to the vehicle.
Eddy Ricciardi, a University of Waterloo Mechanical Engineering student and UW Baja SAE team member, took on the driveline redesign as his fourth year design project, which was supervised by Prof. HJ Kwon.
The teaching objective for this case study is the synthesis and analysis of mechanisms for gears and power transmission system design. The case study includes need analysis, conceptual design, preliminary design (components selection), detail design analysis, and implementation. The case study also provides a detailed analysis and comparisons of key factors for bearing selection and shaft design. This material can be used as an effective material for Mechanical Design 2 (ME423) courses.