Simple Machines: Wheel and Axle

Diagram of a wheel and axle.
Diagram of a wheel and axle. | Source
This style wheel and axle multiplies speed in a horizontal direction/
This style wheel and axle multiplies speed in a horizontal direction/ | Source
This style of wheel and axle multiples force in a verticle direction.
This style of wheel and axle multiples force in a verticle direction. | Source

Simple machines help make work easier for people. One of these simple machines, the wheel and axle, increases our ability to lift heavy items or to move them from one place to another. The wheel and axle uses the mechanics of effort, resistance, speed and force. The earliest known wheel and axle was used in Mesopotamia around the year 3500 BC. It has come to be used in all kinds of modern day inventions from wheelbarrows to cranes.

Wheel and Axle Parts

The wheel and axle consists of two curved part, one large and one small. The larger curved part is the wheel which spins around the smaller curved part - the axle or rod. The axle acts like a fulcrum (a hinge or a pivot point) which spins the wheel.

Examples of the Wheel and Axle

There are a huge number of examples of the wheel and axle in use today. They include:

· egg beaters

· water wheels used in mills

· paddle wheels used on paddle wheel boats

· doorknobs

· screwdrivers

· drills

· cranes

· automobile wheels

· wagon wheels

· Ferris Wheels

· carrousels

· windmills

· rollers skates and roller blades

· bicycles

· rolling pins

· electric fans

· train car trucks (the wheels)

· record player tables

· Lazy Susans

· water wells

· drawer rails

· pulleys

· machine gears

See some pictures of a few of these wheel and axle examples at:

· My Kids: Examples of Wheels and Axles

· http://www.mikids.com/SMachinesWheels.htm

How the Wheel and Axle Works

One way a wheel and axle works is by draping a rope, chain, or cable around a grooved wheel - such as a pulley - and using it to lift and lower heavy objects in a vertical direction. An example here would be a crane or a water well. Another way is to rotate the wheel around the fulcrum (a.k.a. the axle) to make the object move horizontally. An example of this would be any type of vehicle. The effort and force can either be applied to the wheel (as with a doorknob or the wheel on the water well) or to the axle (e.g. car tires or machine gears).

Mechanical Advantage

In mechanical advantage, larger amounts of force applied to the axle makes the wheel move faster - the car or bicycle travels at a faster rate of speed - the wheel and axle are acting as a speed multiplier. Applying force to the wheel so that it moves a longer distance, creates a large force on the axle so that it turns only a smaller distance. In this case, the wheel and axle act as a force multiplier (i.e. windmill, spindle, water well).

A mathematical equation is used to find the mechanical advantage of any wheel and axle set up. That equation is:

wheel radius (or load) ÷ axle radius (or effort) = M.A. (mechanical advantage)

For example, if a bicycle tire has a 24 inch radius, and the axle has a 1.5 inch radius, then the equation would look like this:

24 inches ÷ 1.5 inches = 16

Mechanical advantage is not measured in units, because the effort and the load are both forces. so the equation is essentially dividing a force by a force. Since the two forces cancel each other out, the mechanical advantage is simply listed as a number.

Resources

Science J-Rank. Simple Machines, Wheel and Axle.

http://science.jrank.org/pages/4056/Machines-Simple-Wheel-axle.html

Oracle Think Quest. The Wacky Wheel and Axle.

http://library.thinkquest.org/CR0210120/wheel%20and%20axle.html?tql-iframe

Swirk Interactive Schooling. Wheel and Axle.

http://www.skwirk.com.au/p-c_s-4_u-308_t-757_c-2850/wheel-and-axle/nsw/wheel-and-axle/force-and-motion/machines

Education. Explore Wheels and Axles.

http://www.education.com/activity/article/Wheel_And_Axle/

Pinewood Derby. Pro Wheel and Axle Alignment Tool.

http://www.pinewoodpro.com/pinewood-derby-wheel-axle-alignment-tool.htm

Hot Chalk Lesson Plan Page. Simple Machines, Wheel and Axle.

http://www.lessonplanspage.com/ScienceSimpleMachines-WheelAxle46.htm

Simple Machines - the axle and wheel

Wheels And Axles

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Comments 1 comment

agusfanani profile image

agusfanani 4 years ago from Indonesia

Hi joanwz. That's right wheel and axle play very important roles in our life. Carry things, specially heavy loads are impossible to do if there is no wheel and technology will absolutely be stuck. Thank you for this useful interesting hub.

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