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ANAND INSTITUTE OF HIGHER TECHNOLLOGY –

KAZHIPATTUR 603 103

DEPARTMENT OF MECHANICAL ENGINEERING

SUB.CODE/SUB.NAME:ME6601/DESIGN OF TRANSMISSION SYSTEMS

UNIT 1 DESIGN OF FLEXIBLE DRIVES

DESIGN PROCUDERE FOR FLAT BELT DRIVE BASED ON

MANUFACTURE’S DATA

1.SELECTION OF PULLEY DIAMETERS:

Select the pulley diameters and angle of contact(ie wrap angle) by using the

given belt speed, and assuming number of plies, minimum pulley diameter is

chosen

Use table from PSG DDB Pg.No:7.52 to select diameter of smaller pulley

2.CALCULATION OF DESIGN POWER IN KW

Design KW = Rated KW X Load concentration factor(KS )

Arc of contact (K∞) X small pulley factor (Kd)

Load concentration factor(KS ) : Assuming load conditions PSG DDB Pg.No:7.53

Arc of contact (K∞): arc of contact formula available in DDB PSG DDB Pg.No:7.54

small pulley factor (Kd): this value not available in DDB

Smaller pulley diameter

(d)

Kd

Upto 100mm 0.5

101 – 200mm 0.6

201 – 300mm 0.7

301 – 400mm 0.8

401 – 750mm 0.9

Over 751 above 1.0

3. SELECTION OF BELTING : PSG DDB Pg.No:7.54

4.LOAD RATING CORRECTION: Correct the load rating to the actual load

PSG DDB Pg.No:7.54

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5.DETERMINATION OF BELT WIDTH

Belt Width = design power

Load rating X No.of Plies

Knowing the smaller pulley diameter and velocity of the belt, the no.of plies can be

found from PSG DDB Pg.No:7.52

The calculated belt width should be rounded of to the std. belt width. PSG DDB

Pg.No:7.52

6.DETERMINATION OF PULLEY WIDTH: PSG DDB Pg.No:7.54

7.CALCULATION OF BELT WIDTH: from PSG DDB Pg.No:7.53

DESIGN OF FLAT BELT PULLEYS

1.DIMENSION OF PULLEY:

σc = ρV2

ρ = 7200Kg/m3 for cast iron

V = DN

60 D = dia of Pulley; N = Speed of Pulley

(i) Select the diameter of the pulley (D) from PSG DDB Pg.No:7.54

(ii) Select the width of the pulley (D) from PSG DDB Pg.No:7.54

(iii) Select thickness of the pulley (D) from PSG DDB Pg.No:7.54

2.DIMESIONS OF ARM:

(i) No.of arm : PSG DDB Pg.No:7.56

(ii) Cross section of arms [ b&b/2] : PSG DDB Pg.No:7.56

(iii) Arms Taper : PSG DDB Pg.No:7.56

(iv) Radius of the cross section of arms : r = ¾ X b

3.DIMENSIONS OF HUB:

(i) Dia.of the hub(d1): d1 = [1.7 to 2.0d2] PSG DDB Pg.No:7.56

(ii) length of the hub(l): PSG DDB Pg.No:7.56

4.CROWNING OF PULLEY RIM: select the crown height PSG DDB

Pg.No:7.55

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DESIGN PROCUDERE FOR V BELT DRIVE BASED ON

MANUFACTURE’S DATA

1.SELECTION OF BELT SECTION: select the belt section based on power

transmitted PSG DDB Pg.No:7.58

2.SELECTION OF PULLEY DIAMETERS [d & D]: select the small pulley

diameter from PSG DDB Pg.No:7.58, then using the speed ratio, calculate the

large pulley diameter[D].

These pulleys diameters should be rounded of to the a Std.diameters from PSG

DDB Pg.No:7.54

3.SELECTION OF CENTRE DISTANCE[C]: from PSG DDB Pg.No:7.61

4.DETERMINATION OF NOMINAL PITCH LENGTH: from PSG DDB

Pg.No:7.61

5.SELECTION OF VARIOUS MODIFICATION FACTORS:

(i) Length correction factor [FC]: PSG DDB Pg.No:7.60

(ii) Correction factor for arc of contact [Fd]: PSG DDB Pg.No:7.68

(iii) Service factor [Fa]: PSG DDB Pg.No:7.69

6.CALCULATION OF MAXIMUM POWER CAPACITY: PSG DDB

Pg.No:7.62

7.DETERMINATION OF NO.OF.BELTS (nb) : PSG DDB Pg.No:7.70

8.CALCULATION OF ACTUAL CENTRE DISTANCE: PSG DDB

Pg.No:7.61

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DESIGN PROCUDERE FOR WIRE ROPE

1.SELECTION OF SUITABLE WIRE ROPE: select the rope as per

requirement

2.CALCULATION OF DESIGN LOAD: By assuming the Larger FOS ie 15,

find the Design load PSG DDB Pg.No:9.1

3.SELECTION OF WIRE ROPE: select the wire rope diameter(d) PSG DDB

Pg.No:9.5 -9.6

4.CALCULATION OF SHEAVE DIAMETER(D): PSG DDB Pg.No:9.1

always select the larger dia is preferred

5.SELECTION OF THE AREA OF THE USEFUL CROSS SECTION OF

THE ROPE[A]

Types of construction Metallic area of the Rope(mm2)

6x7 0.38d2

6x19 0.4d2

6x37 0.4d2

8x19 0.35d2

6.CALCULATION OF WIRE DIAMETER(dw)

dw = d

1.5

d = wire rope dia(mm); i = No. of. Strands X No. of wires in each strand

7.SELECTION WEIGHT OF ROPE[Wr]: PSG DDB Pg.No:9.5 -9.6

8.CALCULATION OF VARIOUS LOADS

(i) Direct load Wd = W+Wr

(ii) Bending Load Wb = σb x A = Er.dw/D.A

(iii)Acceleration load due to change in the speed of hoisting

Wa = X a

a = V2 – V1

t

(iv) Starting (or) Stopping load

(a) When there is no slack in the rope:

Starting Load Wst = 2.Wd

(b) When there is slack in the rope:

Starting Load Wst = σst x A

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9.CALCULATION OF EFFECTIVE LOADS

(i) Effective load on the rope during normal working Wen =Wd+Wb

(ii) Effective load on the rope during Acceleration of the load

Wea = Wd+Wb+Wa

(iii) Effective load on the rope during starting Wst = Wb+ Wst

10.CALCULATION OF FACTOR OF SAFETY[Fsw]

Fsw = Breaking load from PSG DDB Pg.No:9.5 -9.6 for selected rope

Effective load during acceleration [Wea]

11.CHECK FOR SAFE DESIGN

If working FOS is greater than the Recommended FOS from PSG DDB Pg.No:9.1

the design is safe and satisfactory

12.CALCULATION OF NO.OF ROPES

No.of.Ropes = Recommended FOS n

Working FOS Fsw

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DESIGN PROCUDERE FOR ROLLER CHAIN

1.SELECTION OF THE TRANSMISSION RATIO:

Select the transmission ratio from PSG DDB Pg.No:7.74

i = Z2/Z1 = n1/n2

Z1 = No of teeth on Sprocket pinion

Z2 = no.of Teeth on Sprocket wheel

n1= Speed of the rotation of pinion (RPM)

n2= Speed of the rotation of wheel(RPM)

2.SELECTION OF NO OF TEETH ON THE DRIVER: select Z1 from PSG

DDB Pg.No:7.74

3.DETERMINATION OF NO.OF TEETH ON THE DRIVEN

SPROCKET(Z2): Z2 = iZ1

4.SELECTION OF STANDARD PITCH: a = [30 to 50] P and obtain

std.pitch(P) from PSG DDB Pg.No:7.74

5.SELECT THE CHAIN TYPE: from PSG DDB Pg.No:7.71 – 7.73

6.CALCULATION OF THE TOTAL LOAD ON THE DRIVING SIDE OF

THE CHAIN(PT):

Total load on the driving side (PT) =

+

+

(i)Tangential force : Pt = 1020N/V

N = Transmitted power in KW

V = Chain Velocity = Z1XPXN1 Or Z2XPXN2

60X1000 60X1000

P=Std.Pitch(mm)

(ii) Centrifugal Tension Pc: m.V2

m = mass of the chain/meter from PSG DDB Pg.No:7.71

(iii) Tension due to sagging (Ps):

Ps = K.W.a

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K = Co efficient of sag from PSG DDB Pg.No:7.78

W = weight of chain / meter = m.g

a = centre distance in meter

7.CALCULATION OF SERVICE FACTOR(KS): from PSG DDB Pg.No:7.76

8.CALCULATION OF DESIGN LOAD:

Design Load = [Total load on the driving side] X service factor

9.CALCULATION OF WORKING FOS(Fsw)

FOS = Breaking load for selected belt from PSG DDB Pg.No:7.71 – 7.73

Design load

= Q/PT X Ks

10.CHECK FOS: compare the working FOS with Recommended FOS from PSG

DDB Pg.No:7.77

11.CHECK FOR THE BEARING STRESS IN THE ROLLER:

σ = Tangential load/ bearing Area = Pt X Ks

A

Now compare the calculated bearing stress value with allowable bearing stress

value from PSG DDB Pg.No:7.77

12.CALCULATION OF ACTUAL LENGTH OF THE CHAIN[L]: from PSG

DDB Pg.No:7.75

13.CALCULATION OF THE EXACT CENTRE DISTANCE: from PSG DDB

Pg.No:7.75

14.CALCULATION OF PITCH CIRCLE DIAMETERS(Pcd):

Pcd of smaller sprocket d1 = P/sin(180/Z1)

Pcd of larger sprocket d2 = P/sin(180/Z2)

Smaller sprocket outside dia: do1 = d1+0.8dr

larger sprocket outside dia: do2 = d2+0.8dr

dr = Dia.of roller from PSG DDB Pg.No:7.71 – 7.73

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UNIT 2 SPUR GEARS & PARALLEL AXIS HELICAL GEARS

DESIGN PROCUDERE FOR SPUR GEAR BASED ON LIFE

1.CALCULATION OF GEAR RATIO (i):

i = Z2/Z1 = N1/N2

2.SELECTION OF MATERIALS: from PSG DDB Pg.No:8.4

3.ASSUME GEAR LIFE: if not give assume 20,000hrs

4.CALCULATION OF DESIGN TORQUE:

[Mt] = Mt.K.Kd.Ko from PSG DDB Pg.No:8.15

Ko = 1 normal load; 1.25 moderate load; 1.5Heavy load

Mt = PX60 [pinion torque]

2 N1

Initially assume K.Kd = 1.3 from PSG DDB Pg.No:8.15

5.CALCULATION OF E,[σb], [σc ]: from PSG DDB Pg.No:8.14

[σb] from PSG DDB Pg.No:8.5

[σc] = CBHBKcl Kgf/m2 OR CRHRCKcl from PSG DDB Pg.No:8.16

6.CALCULATION OF CENTRE DISTANCE[a] from PSG DDB Pg.No:8.13

TABLE 8 = 0.1 to 0.2

7.NO.OF TEETH ON PINION

Z1 for 20º full depth system to avoid interfernce

Z1 for 20º stub depth

Z1 for 14 1/2 º full depth

8.CALCULATION OF MODULE:

m = 2a/(Z1+Z2) Z2 = iXZ1

9.REVISE “a” USING STD.MODULE:

Face width b =

Pitch dia d1 = m.Z1

Value of = b/d1

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10.ASSUME SUITABLE QUALITY OF GEAR: from PSG DDB Pg.No:8.3

TABLE 2

11.REVISE THE DESIGN TORQUE[MT]: Obtain new value for K and Kd

from PSG DDB Pg.No:8.15 and PSG DDB Pg.No:8.16 Table 15

12.CHECK FOR BENDING σb : from PSG DDB Pg.No:8.13A Table 8

Now compare the σb with design bending stress [σb], σb<[σb] design is safe

Check for wear σc from PSG DDB Pg.No:8.13 Table 8; σc<[σc] design is safe

13.CALCULATION OF BASIC DIMENSIONS: from PSG DDB Pg.No:8.22

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DESIGN PROCUDERE FOR HELICAL GEAR BASED ON LIFE

1.SELECTION OF MATERIALS: For corresponding i value and required

hardness select the material from PSG DDB Pg.No:8.4

2.ASSUME LIFE OF GEAR: if not given 20,000hrs

3.CALCULATION OF E,[σb], [σc ]: from PSG DDB Pg.No:8.14,8.16,8.18

4.CALCULATION OF DESIGN TORQUE:

[Mt] = Mt.K.Kd.Ko from PSG DDB Pg.No:8.15

Ko = 1 normal load; 1.25 moderate load; 1.5Heavy load

Mt= PX60 [pinion torque]

2 N1

Initially assume K.Kd = 1.3 from PSG DDB Pg.No:8.15

5.CALCULATION OF CENTRE DISTANCE[a] from PSG DDB Pg.No:8.13

TABLE 8 = 0.5

6.ASSUME Z1

Z1 ; Z2=iZ1

7.CALCULATION OF NORMAL MODULE[mn]:

mn=2acos /Z1+Z2 then revise mn from PSG DDB Pg.No:8.2

8.REVISE CENTRE DISTANCE(a):

d1=mnZ1/cos ; d2= id1

a= mn/cos [Z1+Z2 / 2] from PSG DDB Pg.No:8.22

9.calculate b,Pa,[Mt]

Pa=Pt/ tan = / tan ( not available in DDB)

b= b>Pa

based on these values Revise[Mt]

10.ASSUME SUITABLE QUALITY OF GEARS: based on the velocity select

quality of gears from PSG DDB Pg.No:8.3

11.CALCULATE INDUCED BENDING & COMPRESSIVE STRENGTH:

from PSG DDB Pg.No:8.13 & 8.13A

Then check for Safe design

σb<[σb] design is safe; σc<[σc] design is safe

12.CALCULATION OF BASIC DIMENSIONS: from PSG DDB Pg.No:8.22

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UNIT 3 BEVEL WORM AND CROSS HELICAL GEAR

DESIGN PROCUDERE FOR BEVEL GEAR BASED ON LIFE

1.CALCULATION OF GEAR RATIO (i) & PITCH ANGLES:

i = Z2/Z1 = N1/N2, & tan ; tan

2.SELECTION OF MATERIALS: from PSG DDB Pg.No:8.4

3.ASSUME GEAR LIFE: if not give assume 20,000hrs

4.CALCULATION OF DESIGN TORQUE:

[Mt] = Mt.K.Kd.Ko from PSG DDB Pg.No:8.15

Ko = 1 normal load; 1.25 moderate load; 1.5Heavy load

Mt = PX60 [pinion torque]

2 N1

Initially assume K.Kd = 1.3 from PSG DDB Pg.No:8.15

5.CALCULATION OF E,[σb], [σc ]: from PSG DDB Pg.No:8.14

[σb] from PSG DDB Pg.No:8.18

[σc] = CBHBKcl Kgf/m2 OR CRHRCKcl from PSG DDB Pg.No:8.16

6.CALCULATION OF CONE DISTANCE[R] from PSG DDB Pg.No:8.13

TABLE 8 Y= 3 for initial calculations

7.NO.OF TEETH ON PINION

Z1 for 20º full depth system to avoid interfernce

ZV1=Z1/cos ; ZV2=Z2/cos ; from PSG DDB Pg.No:8.39

8.CALCULATION OF TRANSVERSE MODULE[mt]: from PSG DDB

Pg.No:8.38 TABLE 31

R=0.5mt Z12+Z2

2 ; Choose nearest higher std. module value from

PSG DDB Pg.No:8.2 TABLE 01

9.REVISE “R” USING STD.MODULE:

R=0.5mt Z12+Z2

2 from PSG DDB Pg.No:8.38 TABLE 31

10.CALCULATION OF B,mav,d1av,V and Y

(i)Face width b = R/ Y

(ii) Avg.Module mav = mt - bsin /Z1

(iii)Avg.Pcd d1av= mav.Z1

(iv)Pitch Line velocity V = d1avXZ1 (m/s)

60

(v) Calculate Y =b/d1av

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11.ASSUME SUITABLE QUALITY OF GEAR: from PSG DDB Pg.No:8.3

TABLE 2

12.REVISE THE DESIGN TORQUE[MT]: Obtain new value for K and Kd

from PSG DDB Pg.No:8.15 Table 14 and PSG DDB Pg.No:8.16 Table 15

12.CHECK FOR BENDING σb : from PSG DDB Pg.No:8.13A Table 8

Now compare the σb with design bending stress [σb], σb<[σb] design is safe

Check for wear σc from PSG DDB Pg.No:8.13 Table 8; σc<[σc] design is safe

13.CALCULATION OF BASIC DIMENSIONS: from PSG DDB Pg.No:8.38

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DESIGN PROCUDERE FOR WORM GEAR BASED ON LIFE

1.SELECT THE MATERIALS: from PSG DDB Pg.No:8.45 Table 33

2.CALCULATE THE INITIAL DESIGN TORQUE[Mt]

[Mt] = KKd.Mt

KKd=1 (initially assume)

Mt = PX60 [pinion torque]

2 N2

3.SELECT Z1&Z2: as per efficiency from PSG DDB Pg.No:8.46 Table 37

4.SELECT [σb], [σc]: from PSG DDB Pg.No:8.45 Table 32,33 initially assume

V=3m/s

5.CALCULATE CENTRE DISTANCE(a): q=11 from PSG DDB Pg.No:8.44

6.CALCULATE THE AXIAL MODULE[mx]: from PSG DDB Pg.No:8.43

Table35

mx=2a/(q+Z2+2X) X=0 Assume ; then std.these value from PSGDDB

Pg.No:8.2

7.REVISE THE CENTER DISTANCE “a” : from PSG DDB Pg.No:8.43

Table35

8.CALCULATE d,V, ,Vs

Pitch Dia d1= qXmx; d2=Z2Xmx

Pitch line velocity V = d1N1/60; V2 = d2N2/60;

Lead angle tan = Z1/q

Sliding Velocity Vs = V1/Cos

9.RECALCULATE THE DESIGN CONTACT STRESS [σc]: for

corresponding value of Vs Recalculate [σc] from PSG DDB Pg.No:8.45 Table 32

10.REVISE K,Kd,[Mt]: from PSG DDB Pg.No:8.44

11.CHECK FOR BENDING σb : from PSG DDB Pg.No:8.44

Now compare the σb with design bending stress [σb], σb<[σb] design is safe

Check for wear σc from PSG DDB Pg.No:8.44; σc<[σc] design is safe

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12.CHECK FOR EFFICIENCY:

Mt = 71620 hP/n i*n from PSG DDB Pg.No:8.44

ncal ndes design is safe (if not increase the lead angle )

n from PSG DDB Pg.No:8.49 from graph

14.CALCULATE THE POWER LOSS AND THE AREA REQUIRED TO

DISSIPIATE HEAT:

(1-n)* IP = Kt*A*(to-ta)

15.CALCULATE THE BASIC DIMENSIONS: from PSG DDB Pg.No:8.43

Table 35

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UNIT -4 GEAR BOXES

DESIGN PROCUDERE FOR BEVEL GEAR BASED ON LIFE

1.SELECTION OF SPINDLE SPEEDS

Nmax = n-1

Nmin

n= No.of. Speeds Required; = Step Ratio

Select the Std. Step Ratio from PSG DDB Pg.No:7.20

2.STUCTURAL FORMULA Stage1 Stage2 Stage3 Stage4 n=P1(X1) * P2(X2) * P3(X3) * P4(X4)

X1=1; X2=P1; X3=P1.P2; X4=P1.P2.P3

3.CONSTRUCT THE RAY DIAGRAM:

Draw the Horizontal Lines as per the No.Of. Speeds Required, and Split this

line in to Column as per the No.Of. Satges needed

4.CHECK THE CONDITIONS:

nmin 1/4 nmax 2

ni/p ni/p

But never keep

nmax > nmax

ni/p ni/p

5.KINEMATIC ARRANGEMENT

Mark horizontal lines = No.Of.Satges + 1

Total Gears= (P1+P2)*2

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UNIT – 5 CAM,CLUTCH, BRAKES

FORMULA FOR CLUTCH

1.Frictional Torque:

T = n*µ*W*R If single plate clutch n=2(both sides being effective)

If multi plate clutch n = n1+n2 – 1

n1 = No.of Discs on the Driving Shaft

n2 = No.of Discs on the Driven Shaft

µ = Co-efficient of friction

R = 2/3*(r13 –r2

3/ r1

2 – r2

2 ) - Uniform Pressure

R = r1+r2 / 2 – Uniform Wear

r1,r2 = Outer & Inner diameter Rply

2.POWER

P = 2 NT/60

3.INTENSITY OF PRESSURE

Pmin.r1 = Pmax.r2 = C

AXIAL THRUST W = 2 C[r1-r2]

4.TOTAL NO.OF PLATES REQUIRED

no.of plates required = no.of pair of contact + 1 = Ttotal/Tsurface

CONICAL CLUTCH

T=2/3* µ*W* Cosec (r13 –r2

3/ r1

2 – r2

2 ) - Uniform Pressure

T=µ*W* Cosec (r1+r2/ 2 ) - Uniform Pressure

Brake

T1/T2 = e µº

T1= Tension on tight side

T2= Tension on Slack side

µ = Co-efficient of friction

º = Angle of Lap

BRAKE POWER (TB) = (T1-T2)*r

r= Radius of the drum