American Society for Engineering Education
2015 ASEE Annual Conference & Exposition
Machine Design Experiments Using Gears to Foster Discovery Learning For the typical undergraduate engineering student the topic of gears is introduced and discussed in several courses. Early exposure may be in a physics course or in a first dynamics course,where gear pairs are presented as an idealized means to change speed ratios and torque ratios.They are used for mechanical advantage or to achieve desired speed, and the focus is usually on kinematics. Since gears have inertia they store kinetic energy and are part of the dynamic equations of motion of mechanisms and machines. For mechanical engineering students, gears are a core component studied in courses such as 'kinematics and dynamics of mechanisms' and 'machine design', where the nomenclature and design equations are developed for various types of gears. There may be exposure to real gears in a mechanical engineering laboratory; more often, students may see gears passed around in class and as part of demonstrations.In this paper we describe new experiments that were designed to provide mechanical engineering students with discovery learning experiences with gears and mechanical systems using gears.The suite of practical experiments presents students with a range of challenges that require them to analyze, measure, design, and fabricate gears. Activities in the experiments include: (1) Identifying gear types (spur, helical, bevel, etc.) and appropriate applications (automotive transmissions and differentials, drills, gear head motors). (2) Disassembling and re-assembling a kitchen mixer (with design and manufacturing questions related to its gears). (3) Disassembling and re-assembling an automotive HVAC baffle sub-assembly (with measurement of train ratios, and design and manufacturing questions related to its gears). (4) Designing the gear mechanism for driving the minute and hour hands of a gear clock given a known yet arbitrary drive speed. Fabricating the gears of the clock via rapid prototyping (3D printing), assembling the clock, and then testing the timing accuracy.In addition to reporting the details of the experiments, we share experiences of students and teaching assistants in their use and effectiveness. We provide insights into how well students became familiar with types and nomenclature of gears and understood the applicability of different gears to actual real-world problems. The intent of the experiments is to effectively enhance mechanical engineering students' awareness of gears and expand their knowledge and confidence in the use of gears in machine and mechanism design.
Slightam, Jonathon Earl and Nagurka, Mark L., "Machine Design Experiments Using Gears to Foster Discovery Learning" (2015). Mechanical Engineering Faculty Research and Publications. 211.
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