Intermediate Level 2
Lesson 2
Let's Gear Up!
Gears are one of the mechanical parts used in robots to make them function!
Step 2: Watch this video to learn about gear ratios!
Step 3: Let's review Some Concepts
Torque:
Is a force that can produce a rotation.
Speed: Measures how fast an object goes.
Gear Ratio:
Is the measurement of the arrangement of gears that produce the necessary speed and torque a mechanism requires.
Driver vs Driven
The driver gear, also known as the input, is the gear that will rotate from a power source. Ex: a motor
The driven gear, also known as the output, is the gear that rotates from the driver spinning.
Step 5: Let's see what Robbie the Robot and his friends have to say about gears!
What types of gear ratios are there?
What about when the driver gear is small, and the driven gear is big?
Can you use gears that are the same size?
There are three main types of gear ratios. The first is gearing up. This is when your driver gear is big and your driven gear is small. Having a small gear for output will give you a high speed because it will complete rotations quicker however the torque produced will be lower.
This is called gearing down. This gives you a higher torque output, but the speed decreases because the rotations are slower.
Yes! This is called a
one-to-one ratio. (1-1) This will result in a match of speed and torque.
Step 6: What is Mechanical Advantage?
Mechanical Advantage: is the calculation of how much faster and easier a machine makes your work.
For example when you’re riding a bike up a hill, you might change to a lower gear to make it easier for yourself to pedal while still maintaining the amount of torque needed to get up the hill. This is known as gearing down. You might do the opposite while you’re riding down a hill to pedal slower, this is gearing up.
Step 7: Let's Think About IT!
Read each scenario and discuss with a partner which gear ratio you would use for the task. Use the picture below to help you. Once you have finished discussing, scroll over the rectangles to read the answer.
Scenario #1: Your robot is designed to carry ice cream cones to a freezer, but it must do it quickly so that they don’t melt. The cones are not very heavy but must be carried carefully.
1. What gears would you use on the drive train? Why?
2. What gears would you use on the lift? Why?
Gear up, you want the robot to drive quickly
1-1, your robot needs to be able to carry an item so it will require some torque. If you gear down you have lots of torque you don’t need and your lift will move slowly. If you gear up, the arm will move quickly making it difficult to be careful, and also it may not have enough torque to carry the object.
Scenario #2: Your robot is designed to carry construction pieces to a work zone. The pieces are very heavy and it is very important that the robot does this safely.
1. What gears would you use on the drive train? Why?
Gear down, your robot will move slowly but gearing down will ensure that your robot can handle driving with heavy items.
2. What gears would you use on the lift? Why?
Gear down so that the lift can carry heavy items. the lift will move slowly but in this case speed is not important.
Scenario #3: Your robot is designed to carry a hose through a greenhouse to water the plants. If the robot drives too slowly the plants will get too much water, but if it drives too quickly they won't get enought water. The hose does not wiegh a lot.
1. What gears would you use on the drive train? Why?
1-1 , It's important that your robot doesn't drive too slowly or too quickly. A 1-1 ration will ensure moderate speed and moderate torque.
2. What gears would you use on the lift? Why?
Gear up, your robot needs to carry a hose which is very light. Gearing down or a 1-1 ratio would give you more torque than you need.