Structures and Mechanics with fischertechnik A Car Full of Gears – Level 3

1. Structures and Mechanics with fischertechnik A Car Full of Gears – Level 3

2. What You’ll Learn… • How gears perform many different functions in a modern automobile • How compound gear units such as an automotive transmission function • How differential gears transfer power to the wheels while allowing cars to steer around corners • How gears and levers transform rotary motion into oscillating motion such as in a windshield wiper Stuff You’ll Need… • Fischertechnik Profi Mechanic + Static Set • Mechanic + Static Activity Booklet • Mechanic + Static Assembly Instruction • Digital camera

3. ePortfolio Suggestions… • Before you begin the activities in this Learning Launcher, write down anything you may already know about cars and how they work. • List three interesting things you learned from the What You Should Know… section. • Keep a glossary of new words you learn. Pay particular attention to the bold, italicized words you find. • Take pictures of your fischertechnik models and label each of the parts. • Make a list of as many automotive gear systems as you can. • Give examples of other machines that use similar gears. • Answer each of the questions in the Activity Booklet. Record your observations in your Project Planner. • Create a narrated video demonstrating how your geared machines work.

4. What You Should Know… Before beginning the activities in this Learning Launcher • You should already be very familiar with the fischertechnik construction system. • You should be familiar with the different types of simple machines and understand the basic principles of each. • You should understand how different kinds of gear systems work and be able to calculate gear ratios. If you are not familiar with any of these concepts, you should review the What You Should Know… section of the Level 1 Machines and Gears Learning Launcher.

5. What You Should Know… We can also use gears to provide mechanical advantage. The motor in your fischertechnik kit isn’t very powerful. So, just like the lever in the previous slides, gears allow us to increase distance so we can perform work with less force. Let’s take a closer look at how gears can help machines like you will build with your fischertechnik kit gain mechanical advantage. Gears are variations of the wheel and axle type of simple machine. The teeth on gears transfer work from one gear to another. Remember how we use a lever with one side longer than the other to trade distance for force and gain mechanical advantage? Gears can create mechanical advantage in a similar way by using different size gears with different numbers of teeth. Instead of changing the linear distance we apply force (like we did by pushing down on the lever), we increase or decrease the rotational speed from one gear to another – one gear travels farther in a circle than the other. You will be using gears in many of your SmartLab projects, so it is helpful to learn more about them. You can watch this video if you need to learn more about gears.

6. What You Should Know… A Car Full of Gears… A car is one of the most sophisticated machines many of us will ever use! According to U.S. Department of Transportation, there are currently over 250,000 registered passenger vehicles in the U.S. That averages to about 765 cars per thousand people (that’s ALL people - including those who can’t even drive yet)! Cars are so important that many people use them almost every day. It is sometimes said that Americans have a love affair with the car. But how often do we stop to think about how they work?

7. What You Should Know… A Car Full of Gears… Cars must be engineered to meet some very challenging and diverse design specifications. Many different types of machines go into today’s automobile. Complex gear systems perform a lot of the most important functions. They speed things up, slow things down and change direction of force and movement. In this Learning Launcher you will explore several types of automotive gear systems. They all work very differently, but all are critical systems in every car. How many gear systems can you think of at work in your family car? Before you continue to the next slide, make a list of as many automotive gear systems as you can.

8. What You Should Know… A Car Full of Gears… One of the most important gear systems in a car is the transmission. It allows your car to generate enough power to start moving when the light turns green and to climb steep hills. When speed is more important than power, like on the freeway, it helps your car go faster. It accomplishes this with a compound gear system. This system converts the mechanical energy from the engine to produce more rotational force or torque when power is needed, or rotational speed when the car needs to go faster. The job of a transmission is to switch gears as needed. Some cars do this automatically – this is called an automatic transmission. In some cars, the driver uses a lever to shift gears – this is called manual transmission. Cross-Section of Automobile Transmission

9. What You Should Know… A Car Full of Gears… Another critical gear system is called a differential. Wheels on a car are connected by an axle. The axle transfers power from the engine to rotate the wheels and generate motion. But when you turn a car, the wheels on the outside of the turn must travel farther than those on the inside. If the wheels on the outside of the turn tried to rotate the same amount as those on the inside, you’d be in for a very rough ride (and your tires wouldn’t last very long either)! So how does your car power both wheels while still allowing them to turn at different speeds? That’s where the differential gear comes in! Inside Turning Distance Outside Turning Distance

10. What You Should Know… A Car Full of Gears… The differential is a compound gear system that allows the axle to transfer equal force to each wheel while allowing them to turn at different speeds. The best way to understand how a differential gear works is to build a working model yourself. Fortunately, in the Do It! section of this Learning Launcher you will get to do just that! Cut-Away View of a Differential Gear

11. What You Should Know… A Car Full of Gears… The last type of automobile gear system we will examine is a critical one indeed. The windshield wipers. Many gear systems on a car are rotational systems; they help things turn. But the windshield wiper system must be able to convert the rotational motion of an electric motor to the oscillating (back-and-forth) motion of the wipers. On most cars, they must also synchronize the motion of the two wipers so they can work together. A mechanical system comprised of a crank or cam, a special kind of gear system called a crank rocker gear, and a connecting rod makes it all work! You can explore this kind of mechanical system in the Do It! section next.

12. Do It! Modeling Car Gear Systems… In this Learning Launcher you will build gear systems similar to those that are commonly found in cars. Plans for three are included in your fischertechnik Mechanic + Static kit. Start with the one you find most interesting. If you have time, try to build all three! Be sure to answer the questions in the Activity Booklet for each model you build. The Gearbox with Several Gears is similar to a manual transmission on a car. You can find it on page 27 of the Activity Booklet. Assembly instructions are on page 24 of the Assembly Instruction book. Assembly Instruction Gearbox Activity Booklet

13. Do It! The Differential Gear… You can find the differential gear on page 29 of the Activity Booklet. Assembly instructions can be found on page 40 of the Assembly Instruction book. Differential Gear Assembly Instruction Activity Booklet

14. Do It! The Windshield Wiper… You can find the windshield wiper on page 32 of the Activity Booklet. Assembly instructions can be found on page 56 of the Assembly Instruction book. Windshield Wiper Assembly Instruction Activity Booklet

15. The gearbox is similar to a manual transmission on a car. How do automatic transmissions work? Go online to find out. The windshield wipers on your family car probably have an intermittent setting where they stop and start. Go online to explore the interesting story of their inventor, Robert Kearns. What other mechanical systems can you think of that are used in cars? Can you create a model with the fischertechnik Mechanic + Static kit? Try building some of the other structures in the Mechanic + Static Assembly Instruction book. Or design one of your own. Try building one of the structural devices in the Mechanic + Static Assembly Instruction book. Go online and search for “fischertechnik projects”. Check out some of the amazing things people have built using this sophisticated modeling system. Extend Yourself…