Get in Gear
Figure 1. Example complex drive trains mounted on a LEGO EV3 robot.Copyright 2017 Polytechnic Institute at NYU
Students are introduced to gear transmissions and gear ratios using LEGO® MINDSTORMS® EV3 robots, gears and software. They discover how gears work and how they can be used to adjust a vehicle's power. Specifically, they learn how to build the transmission part of a vehicle by designing gear trains with different gear ratios. Students quickly recognize that some tasks require vehicle speed while others are more suited for vehicle power. They are introduced to torque, which is a twisting force, and to speed—the two traits of all rotating engines, including mobile robots using gears, bicycles and automobiles. Once students learn the principles behind gear ratios, they are put to the test in two simple design activities that illustrate the mechanical advantages of gear ratios. The "robot race" is better suited for a quicker robot while the "robot push" calls for a more powerful robot. A worksheet and post-activity quiz verify that students understand the concepts, including the trade-off between torque and speed.
Students are introduced to gears and the mechanical advantages they provide, which are fundamental tools used by mechanical engineers as they design engines for all sorts of purposes. Students also get a taste of computer science by using the programmable robot. They develop mathematical and logic skills while solving gear train ratio problems that require them to determine gear ratios that are suitable for their robot challenges and the best arrangement of gears in transmissions.
After this activity, students should be able to:
- Describe what gears are and how gear ratios work.
- Design gear trains to produce speed or torque.
- Define torque and speed, and know which gear combinations are more suitable for each.