Machine design experiments using gears to foster discovery learning

Experiments were designed to provide engineering students with opportunities for discovery learning experiences with mechanical systems using gears. This paper describes the experiments, which present students with a range of practical challenges requiring them to analyze, measure, design, and fabricate gears and gear systems. Activities in the experiments include: (1) identifying gear types (spur, helical, bevel, etc.) and appropriate applications (transmissions, differentials, gearmotors, etc.). (2) Disassembling and reassembling an automotive HVAC baffle subassembly (with measurement of train ratios, and design and manufacturing questions related to its gears). (3) Disassembling and reassembling a kitchen mixer (with design and manufacturing questions related to its gears). (4) Designing the gear mechanism for driving the hands of a clock given an input speed, fabricating the gears of the clock via rapid prototyping (3D printing), assembling the clock, and testing the timing accuracy.