Building Mechanical Advantage with Gears
Different Sizes and Types of Gears
A gear's circumference has a direct impact on how the gear transmits torque and speed. When two gears are meshed a mechanical advantage is produced if the circumference of the gears differs. This results in a change to the speed and torque of the axles attached to the gears. This change is proportional to the number of teeth in the gear.
VEX gears have teeth of the same size and spacing. This helps to prevent slippage between gears, ensuring that the attached axles are always synchronized with each other. Having similarly sized and spaced teeth also enables the user to determine the gear ratio.
Help your students to recognize that for one revolution of the large gear, the small gear must rotate seven times thereby spinning seven times as fast.
Gears are commonly used to gain mechanical advantage and for mechanical transmission. Below are some questions to help foster discussion on how gears can be used to gain mechanical advantage.
Q: Where have you seen the use of gears in your everyday life?
A: Cars, tractors, watches, robots, transmissions, and/or trains
Q: How can gears be an important aspect of robot design?
A: Gear ratios can be used to increase speed or torque at the wheel for greater mobility or power. Gears can also be used to change direction of motion. Furthermore, gear ratios can be used with lifting and grabbing mechanisms.
Q: How do gears provide an advantage in the mechanical advantage device you built?
A: If students are familiar with the terminology used in this lesson, they may mention an increase in speed or torque. If not, this is a good opportunity to reinforce the use of those terms.
Extend Your Learning
To expand this activity, instruct your students to explore the various gear types provided with the V5 Classroom Super Kit. Students can then sketch the different types of gears in their engineering notebooks and explain the advantage of each type.
To further expand this activity, instruct your students to investigate how other motion components in their V5 Classroom Super Kit, such as chain and sprocket or belt and pulley, are used to gain mechanical advantage.