Dhruv 10ee57

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A Subject Seminar on

GEAR Prepared By:

Dhruv Upadhyay10EE57

Guided By:

A.B.SOLANKI. Sir

DJMIT MOGAR ANAND

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Abstract

Power transmission is the movement of energy from its place of generation to alocation where it is applied to performing

usef ul work. A gear is a component within a

transmission device that transmitsrotational force to another gear or device .

Gear is very important drive in mechanicalpower transmission. Gear drive is positivedrive.

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Contents Pages

1. Introduction

2. Nomenclature

3.

Types of G

ears4. Spur Gears

5. Helical Gears

6. Bevel gears

7. Worm and worm wheel

8. Rack & Pinion

9. Reference

10. Conclusion

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Introduction

A gear is a toothed wheel with the teeth cut onthe periphery of a cylinder or a cone. It ismounted on the shafts with key. Gear drives is avery important drive in mechanical power

transmiss

ion. The rotat

ing of one gear w

ill ca

userotating of other in the opposite direction. Gear

drive is used to transmit power between shaftsthat are parallel, intersecting or neither parallelnor intersecting. It is transmitted the power whenthe axis of the shafts are not only parallel, but

even when non-parallel, intersecting and co-planer or non-co-planer. It is not suitable forshafts having centre distance.

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NOMENCLATURE OF SPUR

GEARS

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NOMENCLATURE«.

Pitch surface: The surface of the imaginary rolling cylinder (cone, etc.) that the toothed gear may be considered to replace.

Pitch circle: A right section of the pitch surface.

Addendum circle: A circle bounding the ends of the teeth, in

a right section of the gear. Root (or dedendum) circle: The circle bounding the spaces

between the teeth, in a right section of the gear.

Addendum: The radial distance between the pitch circle andthe addendum circle.

Dedendum: The radial distance between the pitch circle andthe root circle.

Clearance: The difference between the dedendum of one gear and the addendum of the mating gear.

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NOMENCLATURE«.

Face of a tooth: That part of the tooth surface lying outsidethe pitch surface.

Flank of a tooth: The part of the tooth surface lying inside the pitch surface.

Circular thickness (also called the tooth thickness): Thethickness of the tooth measured on the pitch circle. It is thelength of an arc and not the length of a straight line.

Tooth space: pitch diameter The distance between adjacentteeth measured on the pitch circle.

Backlash: The difference between the circle thickness of onegear and the tooth space of the mating gear.

Circular pitch (Pc) : The width of a tooth and a space,measured on the pitch circle.

N

D P c

T

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NOMENCLATURE«.

Diametral pitch (Pd): The number of teeth of a gear unit pitchdiameter. The diametral pitch is, by definition, the number of teeth divided by the pitch diameter. That is,

WherePd = diametral pitch

N = number of teeth

D = pitch diameter

Module (m): Pitch diameter divided by number of teeth. The pitch diameter is usually specified in inches or millimeters; inthe former case the module is the inverse of diametral pitch.

m = D/N

D

N P d !

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Type of Gears

Spurs

Helical

Bevel

Worm and Worm Gears

Rack and pinion

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Spur Gears

Are used in transmitting torque between parallel shafts

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SPUR GEAR

Teeth is parallel toaxis of rotation

Transmit power from

one shaft to anotherparallel shaft

Used in Electricscrewdriver,

oscillating sprinkler,windup alarm clock,washing machine andclothes dryer

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Helical Gears

Are used in transmitting torques between parallel or non

parallel shafts, they are not as noisy as spur gears

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Bevel Gears

Are used to transmitrotary motion betweenintersecting shafts

Teeth are formed on conical

surfaces, the teeth could be

straight or spiral.

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WORM AND WORM GEAR

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WORM AND WORM GEAR

Worm gears are used when large gearreductions are needed. It is common forworm gears to have reductions of 20:1,

and even up to 300:1 or greater Worm gears are used widely in material

handling and transportation machinery,machine tools, automobiles etc

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Rack and pinion

Rack and piniongears are used toconvert rotation (From

the pinion) into linearmotion (of the rack)

A perfect example of this is the steeringsystem on many cars

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R eference

www.google.com

www.scribd.com

An text book of ³ELEMENTS OFMECHANICAL ENGINEERING´ by S. M.Bhatt , H. G. Katariya , J. P. Hadiya

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CONCLUSION

From the above presentation we come to know the

importance of gear and where it is used.Gear is very

important in any machine and its main function of gear is to

for power transmission.

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Dhruv 10ee57

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