Understanding Simple Machines

Assembled by Craig Tillmannfrom the following web sites: Inventors Toolbox: The Elements of Machines How Stuff Works Explore Science Beakman and Jax: Levers Delightful Machines

Technology Education Home Pagehttp://www.erols.com/te

LEVERS

INCLINED PLANE

WEDGE

WHEEL AND AXLE

SCREWS

GEARS

PULLEYS

CAMS

MACHINE ELEMENTS

GADGET ANATOMY

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.

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.

Classes of Levers

First Class

Second Class

Third Class

Inclined Plane

Online Multimedia Activity

Requires Shockwave

An inclined plane is a ramp used to reduce the effort needed to raise or lower an object over a vertical height.

Examples of inclined planes:Loading rampStairs or wheelchair rampMountain roadThreaded screw.Inclined plane clock:

http://www.marcdatabase.com/~lemur/rb-rolling-ball.html

Wedge

A wedge converts motion in one direction into a splitting motion that acts at right angles to the blade.

Nearly all cutting machines use the wedge.

A lifting machine may use a wedge to get under a load.

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.

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.

Archimedes screw

Screws

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

CLICK HERE TO:

Learn more about Gears

Bevel Gear

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

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.

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.

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. CLICK HERE TO:

Learn more about pulleys

Pulleys in Action

Cams

A cam is a wheel with shaped bumps on it.

Cams are often connected to rods, levers, or springs.

gravity trip hammer

Cams at WorkA 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.

Other Elements of Machines

Crank and Rod

Ratchet

•Allows a wheel to turn in only one direction. A bar called the "pawl" is fixed above the ratchet wheel.

•When the crank turns, the rod is pushed back and forth.

Chains and Belts

•Connects two separated wheels so that when one turns, the other will turn in the same direction.

Name the simple machines that make up each device.

1.

2. 3.

Gadget Anatomy

What types of simple machines can you find?

In the classroom In the school bus/car At home

Thank You!

I hope you enjoyed this presentation.Feel free to use, distribute and edit as you like. However, please leave my name, email link and the link to my Technology Education Page on the first slide.- Craig