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All About

GEARS

Effort -

the force that is applied to do work; the

push, pull, squeeze or lift provided to use gears to

move an object

Resistance -

the force provided by the object on

which one is trying to do work; the object works

against (pushes back) the effort

Mechanical Advantage (MA) -

a mathematical calculation that reveals how many

times easier a job is to do
MA greater than 1 shows that the gear system

multiplied the effort force, but must move through

a greater distance. MA less than

shows that the

gear system requires greater effort force to

operate but the driven gear moves more quickly

Gear ratio -

a mathematical relationship that

indicates the difference in the size of gears in a

gear system; the rate at which one gear turns

another based on the number of teeth or

diameter of each gear

Diameter -

the distance through the center of an

object; a straight line passing through the center

of a circle ended at the circumference

Work -

the job being done while using the gears

Load -

the object (weight) lifted or moved; provides

resistance to the gears

Force -

any kind of push or pull applied to an object

Bevel -

an angle that is not a right angle; slanted

Key Words and Definitions

What is a Gear?

•

A gear is a wheel with teeth along its outer edge.

•

One gear can make another gear turn when the teeth of the

two gears interlock, mesh or connect.

•

Gears can change the amount of force, the direction and the

speed of rotation needed to do a job.

number of teeth

(driven gear)

number of teeth

(drive gear)

diameter

(driven gear)

diameter

(drive gear)

number of teeth

(large gear)

number of teeth

(small gear)

Gear
Ratio

diameter

(large gear)

diameter

(small gear)

How do gears help you?

•

Gears can change the force needed to make

something move and the speed it moves.

•

One gear affects the way another gear moves

based on how the gears are configured in

the system.

•

Many gears, working together in different

arrangements, allow a single machine to do work

at both different speeds and directions.

•

The Mechanical Advantage, or gear ratio, of a set

of gears, is determined by ratios of: the number of

teeth; the diameters; the speeds of the two gears;

and the amounts of force with which they turn.

Key Concepts

Содержание Education Simple Machines Deluxe GEARS

Страница 1: ......

Страница 2: ...nsors K NEX is a trademark of K NEX Limited Partnership Group Website www knexeducation com Email abcknex knex com Phone 1 888 ABC KNEX USA CAN only K NEX Limited Partnership Group P O Box 700 Hatfiel...

Страница 3: ...on Plan 26 Student Activity Sheet 28 Worm and Worm Gear Lesson Plan 29 Student Activity Sheet 31 Planetary Gears Lesson Plan 32 Student Activity Sheet 34 Simple Transmission Lesson Plan 35 Student Act...

Страница 4: ...ully present selected models and their associated activities We have also provided Student Activity and Reference Sheets These comprise illustrations and definitions of some of the concepts featured i...

Страница 5: ...echnological design Understandings about science and technology Alignment with National Standards Grades 5 8 Reprinted with permission from National Science Education Standards 2001 by the National Ac...

Страница 6: ...ents of design Engineering Design Engineering design process Creativity and considering all ideas Models The role of troubleshooting research and development invention and innovation and experimentati...

Страница 7: ...tion of systems Knowledge from other fields of study and technology The Attributes of design Design leads to useful products and systems There is no perfect design Engineering Design Brainstorming Mod...

Страница 8: ...ob being done while using the gears Load the object weight lifted or moved provides resistance to the gears Force any kind of push or pull applied to an object Bevel an angle that is not a right angle...

Страница 9: ...nt sized spur gears turn at different speeds and with different amounts of force What are sprocket gears Sprocket gears are a special type of spur gears consisting of two gears on the same plane set a...

Страница 10: ...r A gear is a wheel with teeth along its outer edge One gear can make another gear turn when the teeth of the two gears interlock mesh or connect Gears can make work easier by letting you use less for...

Страница 11: ...plat form where people ride A smaller gear with 20 teeth is attached to a motor A Mechanical Advantage of 25 means that the motor turns the small gear 25 times for one turn of the merry go round but...

Страница 12: ...the gears Small and large spur gears work together to make the hands turn at different rates so you can tell the time How do spur gears help you Spur gears of different sizes can help you by making p...

Страница 13: ...w do worm gears help you Worm gears help by letting you turn part of a machine at one speed while you make another part of the machine turn at a much slower or faster speed Worm gears can do this beca...

Страница 14: ...ears then makes the back gear turn The back gear turns the wheel and off you go How do sprocket gears help you A special feature of sprocket gears is that they let you spread your turning action over...

Страница 15: ...ake the drill wobble as it turned and the drill would be difficult to hold Like spur gears crown gears can be different sizes Then the crown gears will turn at different speeds and with different amou...

Страница 16: ...ange round and round motion into back and forth motion These gears make it easy to steer a car You can turn the wheel a little to make the car angle to the right or left or turn it a lot to make a sha...

Страница 17: ...6 1 gear ratios Explanatory paragraph for results of tests on 1 1 and 6 1 Spur Gear models Description of the difference between spur gear size and their functional advantage s Explanation of the rela...

Страница 18: ...r make for one turn of the yellow Gear Based on your observation what is the gear ratio for this model Why would you need to use spur gears that have different ratios b Repeat Activity 2 testing the w...

Страница 19: ...rank to lift the weight Feel how much force it takes to do this Connect the K NEX Rubber Band Scale to the end of the top Gear s crank Measure the amount of force used to lift the weight Record your f...

Страница 20: ...ng sprocket gear configurations Explanation of how force measurements support observations Description of why bicycles are best served by sprocket gears Lists of other machines which use sprocket gear...

Страница 21: ...find that they must turn the pedals which are attached to the small Gears about 2 5 turns for every turn of the wheel which is attached to the large Gears The pedals turn easily but the wheel doesn t...

Страница 22: ...Wheel Measure the force used to turn the pedals with the K NEX Rubber Band Scale Snap the orange Connector at the bottom of the Scale to the blue Rod on the pedal Record your results 2 a Add extra li...

Страница 23: ...ns Force measurements for crown gear arrangements Gear ratios for sets of crown gears Description of how crown gears can do work in a newly designed potter s wheel The Crown Gears Lesson Plan Material...

Страница 24: ...th spur gears This may be hard to see because the two Gears lie in dif ferent planes Look at the Crown Gears at the inside corner where the two Gears mesh 2 Crown gears of the same size turn with the...

Страница 25: ...pur Gears Record your findings Did the Crown Gears reduce the force needed to lift the weight Why or why not 3 a Try replacing one small Gear in your Crown Gears model with a big yellow Gear You will...

Страница 26: ...s for turning the pinion and its relationship to rack movement Illustration of design for rack and pinion invention Description of how cog railways work The Rack and Pinion Gears Lesson Plan Materials...

Страница 27: ...connect the front wheels and the steering columns in some cars Investigate vehicles which use this gear system and build a K NEX vehicle of your own design with a rack and pinion steering system 1 1...

Страница 28: ...faster Write a sentence describing how the size of the pinion affects the distance the rack moves 3 Move the rack all the way to the left and rest a small ball on the red Rods at the right Turn the p...

Страница 29: ...ly back and forth Journal Check Explanation of how a worm and worm gear function Illustration of the direction worms and worm gears turn Number of rotations of the Worm Gear in one minute Number of te...

Страница 30: ...not used near water and that students have dry hands when handling the plug 1 Worm gears change the direction of motion Like bevel or crown gears the worm turns in one plane and the worm gear in a pla...

Страница 31: ...turns 2 a Watch the Worm turn You can see that it spins very fast Then watch the Worm Gear turn and have a partner help you count the number of times it turns in 60 seconds Mark one spot with tape or...

Страница 32: ...parative measurements for the rotation of the planet and annulus gears Measurements with different Planetary Gear components locked in place Force measurements for each gear arrangement Explanation as...

Страница 33: ...answers will vary but should include the sun gear is central like the sun in our solar system the planet gears orbit or revolve around the sun gear and each planet gear also turns on its axis axle as...

Страница 34: ...ing why both the sun and planet gears are suitably named 2 a Experiment with locking different Gears in place to see how the speed of the wheel changes First lock the planet and annulus gears together...

Страница 35: ...mple Transmission works and how the Gears link up Explanation of which gearshift placement turns faster and why Identification and explanation of the three different gear positions and their proper na...

Страница 36: ...center gearshift position leaves the upper shaft in neutral the Motor is still running but it isn t driving anything Shifting to the right makes the upper shaft turn at low speed while shifting to th...

Страница 37: ...makes the shaft turn faster shifting the Gears to the right or to the left Explain why c This Simple Transmission has three positions first gear second gear and neutral These are also referred to as...

Страница 38: ...t Gears and resulting gear ratios and MAs Calculations of gear ratios Comparison of Gears and ratio function Description of Gear function if Gear configuration was reversed Assessment of rack and pini...

Страница 39: ...han one half turn The Mechanical Advantage for these Gears is 2 43 b The blue Gear on the top axle turns a little less than half a turn when the crank turns a full turn It turns the same amount as the...

Страница 40: ...Be careful not to overwind the window or the blue Rod will pop off How much does the yellow Gear turn What is the Mechanical Advantage for this gear system b Now turn the crank one full turn again and...

Страница 41: ...dentify the type s of gear used in a lawnmower Demonstrate how a lawnmower functions Explain the advantages offered by spur gears and their effect on force and speed Determine if the spur gears in the...

Страница 42: ...ter than the wheels b Make sure to count the inner circle of teeth on the large green Gear it has 62 teeth The small Gear has 14 teeth The gear ratio is about 4 4 1 You apply the effort to push the La...

Страница 43: ...the small number This ratio tells you how much faster one gear turns compared to the other when a large gear drives a small gear 2 What kind of gears does the Lawnmower use spur crown rack and pinion...

Страница 44: ...he work Observation of the direction the beaters turn and how this affects their work Explanation of the best arrangement for beaters Written and illustrated advertisement for the Eggbeater The Eggbea...

Страница 45: ...ers turn in opposite directions Using spur gears would probably not work as well because then you would have to do your turning in a horizontal plane at the top of the Eggbeater where you hold it whic...

Страница 46: ...work as well if it used spur gears Explain 2 a Fill a bowl or laundry tub about 6 centimeters deep with water Then add a small amount of dish soap Use a spoon to stir the mixture Time how long it tak...

Страница 47: ...regarding the speed of the beaters if gear sizes were changed Explanation of why two beaters are required in the mixer as opposed to one Assessment of the effectiveness of the beaters if they both tu...

Страница 48: ...g the transformer into the wall yourself and let them connect the small plug to the Motor Make sure the Motor is not used near water and that students have dry hands when handling the plug 1 In the Fo...

Страница 49: ...ing 2 If you changed the blue Gears on the shafts of the beaters to larger Gears would the beaters turn faster slower or at the same speed Predict what would happen Write down your prediction and then...

Страница 50: ...to be able to turn at different speeds Journal Check Description of how the Axle model works and why Description of how the Axle with Differential works and why Explanation of the movement of the Gear...

Страница 51: ...When students try to make a turn using the Axle model they should feel a strain as one wheel lags behind the other They may notice that the wheel on the outside of the turn may slip to keep up with th...

Страница 52: ...t happens Push the model around a sharp turn What do you notice Describe what happens when this model makes a turn Why does this happen 2 a Now build the Axle with Differential as shown in figure B in...

Страница 53: ...clock Explanation of how the gear configurations affect the function of the Clock Description and effects of modifications made to gear configurations Creative story about the Clock The Clock Lesson P...

Страница 54: ...what students have learned about gears and assess their understanding by seeing if they can identify the various gear systems within this model 1 The minute hand on the K NEX Clock turns 36 times for...

Страница 55: ...h hands are pointing straight up Then start your Clock stopping it each time the minute hand points straight up Make a mark where the hour hand points Keep going until you have marked the whole face b...

Страница 56: ...4 3 1 7 3 13 14 0 0 10 10 14 Red Rod 4 7 2 5 1 4 0 5 5 6 8 5 1 8 Gray Rod 1 2 0 2 0 0 2 0 3 0 0 0 0 6 Med Tire 0 1 0 0 0 1 0 0 0 0 0 0 0 1 Lge Pulley 0 1 0 0 0 1 0 0 0 0 0 0 0 1 Motor Assembly 0 0 0...

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