Gears PP Presentation

8/14/2019 Gears PP Presentation

1/25

GEARSGEARS

Introduction toIntroduction to

Engineering andEngineering and

Technology ConceptsTechnology Concepts


2/25

GEARSGEARS

A wheel with a number ofA wheel with a number ofteeth wrapped around theteeth wrapped around the

circumference.circumference.When two gears are meshedWhen two gears are meshed

together, the rotation oftogether, the rotation of

driver and follower aredriver and follower arealwaysalway

s opposite.opposite.


3/25

GEARS vs. PULLEYSGEARS vs. PULLEYS

Gears do not creep or slipGears do not creep or slip Gears change direction ofGears change direction of

motionmotion

Mechanical advantage isMechanical advantage iscalculated by countingcalculated by countingnumber of teethnumber of teeth


4/25

GEARSGEARS

Common uses include:Common uses include:

Transmit motionTransmit motion Change direction of motionChange direction of motion Magnify output speedMagnify output speed Magnify output forceMagnify output force


5/25

GEAR USESGEAR USES

You can see effects 1, 2 and 3 in the figure above.You can see effects 1, 2 and 3 in the figure above.

In this figure, you can see that the two gears areIn this figure, you can see that the two gears arerotating in opposite directions, that the smallerrotating in opposite directions, that the smallergear is spinning twice as fast as the larger gear,gear is spinning twice as fast as the larger gear,and that theand that the axis of rotationxis of rotation of the smaller gearof the smaller gearis to the right of the axis of rotation of the largeris to the right of the axis of rotation of the largergear.gear.


6/25

GEAR TYPESGEAR TYPES

Spur GearsSpur Gears

Idler GearIdler Gear


7/25



8/25



9/25



10/25



11/25

GEAR TRAINSGEAR TRAINS

A series of 2 or more gearsA series of 2 or more gears

is called ais called a gear traingear train..In a gear train we have a gear knownIn a gear train we have a gear knownas theas the dr iverr iver and one known as theand one known as thef o l l owero l l ower ..Dr iver -r iver - is the gear that has theis the gear that has theforce or motion input.force or motion input.

Fo l lower -o l low er - is the gear that results inis the gear that results inthe force or motion output.the force or motion output.


12/25


Gear Ratio = Driver : FollowerGear Ratio = Driver : Follower

For example, if a motor is attached to aFor example, if a motor is attached to a

gear with 60 teeth and this gear is thengear with 60 teeth and this gear is then

attached to a gear with 20 teeth that drivesattached to a gear with 20 teeth that drives

a wheel, our gear ratio is 60:20, or morea wheel, our gear ratio is 60:20, or more

accurately 3:1accurately 3:1


13/25


If the driver is smaller thanIf the driver is smaller than

the follower, force isthe follower, force ismultiplied.multiplied.

If the driver is bigger than theIf the driver is bigger than the

follower, speed is multiplied.follower, speed is multiplied.


14/25


The purple gear in the train is actually made in twoThe purple gear in the train is actually made in two

parts. A small gear and a larger gear areparts. A small gear and a larger gear are

connected together, one on top of the other. Gearconnected together, one on top of the other. Gear

trains often consist of multiple gears in the train.trains often consist of multiple gears in the train.


15/25



16/25



17/25


Calculating Speed ChangeCalculating Speed Change

SS

dd X TX T

dd = S= S

ff X TX T

ffSSd =d = Speed of DriverSpeed of Driver

TTdd== Teeth of DriverTeeth of Driver

SSff

==

Speed of FollowerSpeed of Follower

TTff== Teeth of FollowerTeeth of Follower

SSdd = S= Sff X (TX (Tff T Tdd))


18/25


A driver gear is moving at aA driver gear is moving at arate of 500 rpm. If the driverrate of 500 rpm. If the drivergear has 10 teeth and thegear has 10 teeth and thefollower has 5 teeth, howfollower has 5 teeth, howfast is the follower going?fast is the follower going?


19/25


A driver gear is moving at aA driver gear is moving at arate of 300 rpm. If the driverrate of 300 rpm. If the drivergear has 15 teeth and thegear has 15 teeth and thefollower has 50 teeth, howfollower has 50 teeth, howfast is the follower going?fast is the follower going?


20/25


Calculating Force ChangeCalculating Force Change

(Mechanical Advantage)(Mechanical Advantage)

MA = TMA = Tff T T

dd


21/25


A driver gear is moving at aA driver gear is moving at arate of 500 rpm. If the driverrate of 500 rpm. If the driver

gear has 10 teeth and thegear has 10 teeth and thefollower has 5 teeth, whatfollower has 5 teeth, whatis the mechanicalis the mechanicaladvantage?advantage?


22/25


A driver gear is moving at aA driver gear is moving at arate of 300 rpm. If the driverrate of 300 rpm. If the driver

gear has 15 teeth and thegear has 15 teeth and thefollower has 50 teeth, whatfollower has 50 teeth, whatis the mechanicalis the mechanicaladvantage?advantage?


23/25


Number of TeethNumber of Teeth

Gear A = 32Gear A = 32 Gear B = 8Gear B = 8

Gear C = 8Gear C = 8 Speed or ForceSpeed or Force

Multiplier?Multiplier?


24/25


If a force of 10N is applied to the driver, whatIf a force of 10N is applied to the driver, whatis the turning force that results on the shaftis the turning force that results on the shaftof the follower?of the follower?


25/25


If a force of 110N is applied to the driver,If a force of 110N is applied to the driver,what is the turning force that results on thewhat is the turning force that results on theshaft of the follower?shaft of the follower?

Gears PP Presentation

Documents

Transcript of Gears PP Presentation