PLANETARYGears

8/7/2019 PLANETARYGears

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Introduction

Planetary gear-sets are served

the same functions as any other

types of gear-sets, but withdifferent construction and

operation principles.


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Gear sets are:-

A number of gears properly engaged

together, consists of a driver gear, and a

driven gear, may or may not have idler

gear/s.

It is used to:-

(i) transmit power

(ii) increase torque or speed

(iii) changing rotating direction


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Simple gear-set

Driver gear

Idler gear/s

Driven gear

Input shaft

Output shaft

Idler shaft


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Compound gear-set

Input shaft

Driver gear

Idler gear 1

Idler shaft Idler gear 2

Driven gear

Output shaft


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Planetary Gear-set


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Functions of Planetary Gears

Transmit power

Increase torque

Increase speed

Changing rotating direction


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Construction

Consists of

A Sun Gear

A Ring Gear

A number of Planet Gears

A Carrier


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Operation

By selecting a driver, a driven,

and a control member from theSun Gear, Ring Gear, & The

Carrier.


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Operation 1

Sun gear

Planet

gear

Ring gear

Carrier


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Operation 1A

Input:

Sun Gear

Output:

Ring Gear

Input shaft fitted to sun gear, output shaft fitted to ring gear


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Operation 1B

Input:

Sun Gear

Output:

Ring Gear

Control: Carrier

Ifpowerdeliver to sun gear, but the ring geardoes not

rotate, the output shaft does not turn, insteadof, the carrier

turn.So how to cause the ring gear/output shaft to rotate?

Control: Carrier Control: Carrier


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Operation 1C

Input:

Sun Gear

Output:

Ring Gear

Control: Carrier by using a brake to stop the carrier for rotating.

Apply Brake to Hold the Carrier


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Operation 1E

Input:

Sun Gear

Output:

Ring Gear

Control: Carrier


Torque: __+____

Speed: _______

Direction: Opposite

Sun Gear: 30 T

Ring Gear: 60 T

A small geardriver,

and a big geardriven.


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Operation 1F

Input:

Sun Gear

Output:

Ring Gear

Control: Carrier


Torque: _______

Speed: ________

Direction: _____

Gear Ratio = R / S

Sun Gear: 30 T

Ring Gear: 60 T

G.R. = 60/30 = 2 : 1


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Size of Gears

Sun Gear = S Ring Gear = R

Carrier = R + S

Remarks: The smallest gear: Sun Gear

The largest gear: Carrier

The medium size gear: Ring Gear

To provide maximum torque multiplication: Sun gear must

be the driver, Carrier must be the driven, and Ring gear

must be control member accordingly.


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Operation 2

Input:

Sun Gear

Output:

Carrier

Control: Ring Gear

Apply Brake to Hold the Ring Gear

Torque: _______

Speed: ________

Direction: _____

Gear Ratio = R / S

Sun Gear: 30 T

Ring Gear: 60 T

Carrier (R+S): 90 T

G.R. = 90/30 = 3 : 1


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Operation 3

Input:Carrier

Output:

Ring Gear

Control:

Sun Gear

Apply Brake to Hold the Sun Gear

Torque: _______

Speed: ________

Direction: _____

Gear Ratio = R / S

Sun Gear: 30 T

Ring Gear: 60 T

Carrier (R+S): 90 T

G.R. = 60/90 = 0.67 : 1


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Operation 4

Input:Carrier

Output:

Sun Gear

Control:

Ring Gear


Torque: _______

Speed: ________

Direction: _____

Gear Ratio = S / C

Sun Gear: 30 T

Ring Gear: 60 T

Carrier (R+S): 90 T

G.R. = 30/90 = 0.33 : 1


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Operation 5

Input:

Ring Gear

Output:

Carrier

Control:

Sun Gear

Apply Brake to Hold the Sun Gear

Torque: _______

Speed: ________

Direction: _____

Gear Ratio = C / R

Sun Gear: 30 T

Ring Gear: 60 T

Carrier (R+S): 90 T

G.R. = 90/60 = 1.5 : 1


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Operation 6

Input:

Ring Gear

Output:

Sun Gear

Control:

Carrier


Torque: _______

Speed: ________

Direction: _____

Gear Ratio = S / R

Sun Gear: 30 T

Ring Gear: 60 T

Carrier (R+S): 90 T

G.R. = 30/60 = 0.5 : 1


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Operation 7

Input:

Sun Gear

Output:

Carrier

Control:

Ring Gear

Apply Clutch to Lock theRing Gear & Carrier

Torque: _______

Speed: ________

Direction: _____

Gear Ratio = 1 : 1

Sun Gear: 30 T

Ring Gear: 60 T

Carrier (R+S): 90 T

G.R. = 1 : 1

(Direct Drive)


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Advantages

All gears are constant mesh, gear ratio can

be change by applying brake or clutch and

involve not moving parts.

Compactness, input & output members are

co-center, without using of counter shaft.

Able to provide many gear ratios and

rotating directions.

Able to withstand heavy loads.

Smooth and quiet operation.


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Applications

Automatic Transmissions

Heavy Vehicle Axles


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No Input Output Hold Speed Torque Direction Gear

Ratio

1 Sun Ring Carrier Dec Inc Opposite R/S =

2:1

2 Ring Sun Carrier Inc Dec Opposite S/R =

0.5 : 1

3 Carrier Sun Ring Inc Dec Forward

(Same)

S/C =

0.3 : 1

4 Sun Carrier Ring Forward(Same)

C/S =

5 Ring Carrier Sun Forward

(Same)

C/R =

6 Carrier Ring Sun Forward

(Same)

R/C =

7 Same Same Forward

(Same)

1 : 1

Direct

8 NA NA NA NA

S C R

LockAny Two Members

Hold None, Neutral


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No Input Output Hold Speed Torque Direction Gear

Ratio

1 Sun Ring Carrier Dec Inc Opposite R/S =

2:1

2 Ring Sun Carrier Inc Dec Opposite S/R =

0.5 : 1

3 Carrier Sun Ring Inc Dec Forward

(Same)

S/C =

0.3 : 1

4 Sun Carrier Ring Dec IncF

orward(Same)

C/S =3 : 1

5 Ring Carrier Sun Dec Inc Forward

(Same)

C/R =

1.5 : 1

6 Carrier Ring Sun Inc Dec Forward

(Same)

R/C =

0.67 : 17 Same Same Forward

(Same)

1 : 1

Direct

8 NA NA NA NA

S C R

LockAny Two Members

Hold None, Neutral


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Operation Summary 1

Input:

Sun Gear

Output:

Carrier

Control: Ring Gear


Torque: _______

Speed: ________

Direction: _____

Gear Ratio = R / S

Sun Gear: 30 T

Ring Gear: 60 T

Carrier (R+S): 90 T

G.R. = 90/30 = 3 : 1


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Operation Summary 2

Input:

Sun Gear

Output:

Carrier

Control:

Ring Gear


Torque: _______

Speed: ________

Direction: _____

Gear Ratio = 1 : 1

Sun Gear: 30 T

Ring Gear: 60 T

Carrier (R+S): 90 T

G.R. = 1 : 1

(Direct Drive)


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Operation Conclusion

Input:

Sun Gear

Output:

Carrier

Control:

Ring Gear


Torque: _______

Speed: ________

Direction: _____

Gear Ratio = 1 : 1

Sun Gear: 30 T

Ring Gear: 60 T

Carrier (R+S): 90 T

Apply Brake to Hold

The Ring Gear

G.R. = C/S

= 3 : 1


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However, a Single set of planetary

gear set can only provide Two GearSpeeds which is not enough for the

usage in the automotive requirement

To provide more gear speeds, there

should combine Two or more

planetary gear sets and using moreclutches or brakes to control the

engaging of gear speeds.


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Operation 8

Sun Gear: 30 T

Ring Gear: 60 T

Carrier

(R+S): 90 T

A

pplyB

1 & C4

Brake 1 Brake 2

Clutch 3 Clutch 4

Apply B1 & B2, Gear Ratio = : 1, Gear Speed:

A

pply C3 &B

2A

pply C3 & C4

9 1st Gear


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Summary of the operation of planetary gear set

Select 1 driver, 1 driven, and 1 control. Apply Brake orClutch to Hold or Lock the

control member.

Hold None forNeutral.

Lock members for Direct Drive

Hold Carrier for Reverse Drive

Input Sun, Output Carrier & Hold Ring for

Maximum Torque Multiplication.

The size of gear members, S = S, R = R, &

C = R + S


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1 In a simple planetary gears, if the

sun gear rotates clockwise, with thecarrier held, the ring gear will

(A) not turn

(B) turn counter clockwise

(C) turn clockwise

(D) lock up with the sun gear( )


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2 A simple planetary gears

provided maximum torquemultiply when the

(A) carrier is driving and the ring gear is held

(B) sun gear is driving and the carrier is held

(C) sun gear is driving and the ring gear is held

(D) ring gear is driving and the sun gear is held( )


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3 When 2 members of a simple

planetary gears are lockedtogether, the gear ratio is

(A) 3 : 1

(B) 2 : 1

(C) 1 : 1

(D) 0.5 : 1( )


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4 To ensure torque multiplication,

in a simple planetary gears, thesun gear need to become the

(A) control member

(B) neutral/free member

(C) driver/input member

(D) driven/output member( )


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5 Mesh the following operation

conditions in a simple planetarygear system

(A) Reverse drive (i ) Hold none

(B) Direct drive (ii ) Hold ring gear

(C) Max. Torque drive (iii) Lock members

(D) Neutral (iv ) Hold carrier


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5 Mesh the following operation

conditions in a simple planetarygear system

(A) Reverse drive (i ) Hold none

(B) Direct drive (ii ) Hold ring gear

(C) Max. Torque drive (iii) Lock members

(D) Neutral (iv ) Hold carrier


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6 Name the parts in the following

Fig.1

X: ________

Y: ________

Z: ________

W: _______Fig.1


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6 Name the parts in the following

Fig.1

X: ________

Y: ________

Z: ________

W: _______Fig.1

Planet gear

Carrier

Sun gear

Ring gear


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7 Fig 2 show a simple planetary gear system in

operation. If the input shaft rotates at a speed of

1500 rpm, calculate the gear ratio and the output

shaft rotating speed.

Solution:

1 List the size of gears

2 List the function of

gears

3 List the speed of

gears

4 List the direction of

gears

Fig.2


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Solution

Sun gear: 30T

Ring gear: 60T

Carrier: 90T

Driver

Control/Hold

Driven

1,500 rpm

0 rpm

X rpm

A: Gear Ratio = Driven/Driver = Carrier/Sun gear

= 90/30 = 3 : 1

B: GASize x GAspeed = GBSize x GBspeed

90 x X = 30 x 1500

X = 30 x 1500 / 90 = 500 rpm.


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A

uto TransB

rakes & Clutches

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PLANETARYGears