Understanding Simple Machines

1. Understanding Simple Machines Assembled by Craig Tillmann from the following web sites: Inventors Toolbox: The Elements of Machines How Stuff Works Explore Science Beakman and Jax: Levers Delightful Machines Levers Inclined Plane Wedge Wheel and Axle Screws Gears Pulleys Cams Machine Elements Gadget Anatomy Technology Education Home Page http://www.erols.com/te Modified by the GA Agriculture Education Curriculum Office July 2002

2. Levers All levers have 3 parts: the fulcrum, the load, and the effort. The fulcrum is the pivot point. When it's right in the middle of the lever, the amount of effort you push down equals the amount of load you can lift. Learn more about levers Water Powered Simple Machine

3. Moving the Fulcrum Here the fulcrum is closer to the load. The distance from the effort end to the fulcrum is twice the distance from the fulcrum to the load. You only have to push down half as hard to lift the same weight. The trade-off is you have to push down a longer distance.

4. Classes of Levers First Class Second Class Third Class

5. Inclined Plane Examples of inclined planes: Loading ramp Stairs or wheelchair ramp Mountain road Threaded screw. Inclined Plane Clocks An inclined plane is a ramp used to reduce the effort needed to raise or lower an object over a vertical height. Online Multimedia Activity Requires Shockwave

6. Wedge Nearly all cutting machines use the wedge. A lifting machine may use a wedge to get under a load. A wedge converts motion in one direction into a splitting motion that acts at right angles to the blade.

7. Wheel and Axle • A wheel or spoke is locked to a central axle so that when one is turned the other must turn. • A longer motion at the edge of the wheel is converted to a shorter more powerful motion at the axle.

8. Screws Archimedes screw A screw is a central core with a thread or groove(inclined plane) wrapped around it to form a helix. While turning, a screw converts a rotary motion into a forward or backward motion.

9. Gears Gears are toothed or pegged wheels meshed together to transmit motion and force. The larger gear will rotate more slowly than the smaller one, but will rotate with greater force. Each gear in a series reverses the direction of rotation of the previous gear. Bevel Gear Rack and Pinion Worm Gear Learn more about Gears

10. Bevel Gear • Bevel Gears are Gears that mesh at an angle and change the direction rotation.

11. Rack and Pinion • A single gear, the pinion, meshes with a sliding toothed rack. • This combination converts rotary motion to linear motion. • Windshield wipers are powered by a rack and pinion gear.

12. Worm Gear • combination of a gear meshed with the threads of a screw. • changes the direction of turning motion by ninety degrees. • decreases the speed of turning from screw to gear and increase its force. Click Image for animation

13. Pulley System • A single pulley reverses the direction of a force. • When two pulleys are connected, they permit a heavy load to be lifted with less force. • The trade-off is that the end of the rope must move a greater distance than the load. Learn more about pulleys

14. Pulleys in Action

15. Cams • A cam is a wheel with shaped bumps on it. • Cams are often connected to rods, levers, or springs. gravity trip hammer

16. Cams at Work A Crank Shaft changes the linear motion of the piston to a rotary motion. A Cam Shaft is connected to the Crank by gears, belts or chains. It changes rotary motion to linear motion to open and close valves.

17. Other Elements of Machines Crank and Rod Ratchet Chains and Belts • Connects two separated wheels so that when one turns, the other will turn in the same direction. • When the crank turns, the rod is pushed back and forth. • Allows a wheel to turn in only one direction. A bar called the "pawl" is fixed above the ratchet wheel.

18. Gadget Anatomy 1. Name the simple machines that make up each device. 2. 3.