Machine Design Databook 2010 Part 8 pdf

THREADED FASTENERS AND SCREWS FOR POWER TRANSMISSION 18.55THREADED FASTENERS AND SCREWS FOR POWER TRANSMISSION... THREADED FASTENERS AND SCREWS FOR POWER TRANSMISSION 18.57THREADED FASTE

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TABLE 18-35

Machine screw heads—pan, hexagon, truss, and 1008 Flat heads

Max diam, head, of slot, of slot, head diam, head, of slot, of slot,

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TABLE 18-35

Machine screw heads—pan, hexagon, truss, and 1008 Flat heads (Cont.)

Max diam, head, of slot, of slot, head diam, head, of slot, of slot,

Note: Radius of ﬁllet at base of truss- and pan-head machine screws shall not exceed one-half the pitch of the screw thread.

Truss-, pan-, and 100 8 ﬂat-head machine screws may be furnished with cross-recessed heads.

Hexagon-head machine screws are usually not slotted; the slot is optional Also optional is an upset-head type for hexagon-head machine screws of sizes 4, 5, 8, 12, and 1 in.

Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com)

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TABLE 18-36

Machine-screw heads—binding head

Max diam, of head, of slot, of slot, of oval, undercut,a undercut,

Use of undercut is optional.

Note: Binding-head machine screws may be furnished with cross-recessed heads.

THREADED FASTENERS AND SCREWS FOR POWER TRANSMISSION 18.55THREADED FASTENERS AND SCREWS FOR POWER TRANSMISSION

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TABLE 18-37

Slotted-head cap screws28

Nominal

diam, slot diam, head, of head, slot, diam, head slot, diam, head, slot,

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TABLE 18-38

Socket-head cap screws

a Maximum socket depth T should not exceed three-fourths of minimum head height H.

Note : Head chamfer angle E is 28 to 328, the edge between ﬂat and chamfer being slightly rounded.

Screw point chamfer angle 35 to 40 8, the chamfer extending to the bottom of the thread Edge between ﬂat and chamfer is slightly rounded.

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TABLE 18-39

Square-head set screws28

ﬂats corners Height of head neck relief head relief relief

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TABLE 18-40

Square-head setscrew points28

Full-dog, half-dog, and pivot pointaOval

Pivot points are similar to full-dog point except that the point is rounded by a radius equal to J.

Where usable length of thread is less than the nominal diameter, half-dog point shall be used.

When length equals nominal diameter or less, Y ¼ 1188 28; when length exceeds nominal diameter, Y ¼ 908 28

Note: All dimensions are given in inches.

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TABLE 18-41

Slotted headless setscrews28

Radius of Width Depth Oval- Diam of cup and Diam of Length of

Where usable length thread is less than the nominal diameter, half-dog point shall be used.

When L (length of screw) equals nominal diameter or less, Y ¼ 1188 28; when L exceeds nominal diameter, Y ¼ 908 28.

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TABLE 18-43

American National Standard metric hex cap screws (ANSI B18.2.3.1M-1979, R1989)

All dimensions are in millimeters.

This size with width across flats of 15 mm is not standard Unless specifically ordered hex cap screws with 16 mm width across flats will be

furnished.

† Transition thread length, X, includes the length of incomplete threads and tolerances gaging length and body length It is intended for calculation purposes.

‡ Basic thread lengths, B, are the same as given in Table 18-47.

For additional manufacturing and acceptance speciﬁcations, reference should be made to Standard.

Courtesy: American National Standards Institution, New York, USA (ANSI B18.2.1M-1979, R1989)

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TABLE 18-44

American National Standard metric formed hex screws (ANSI B18.2.3.2M-1979, R1989)

screw Body diam, ﬂats, corners, height, height, face thickness, face diam,

This size with width across flats of 15 mm is not standard Unless specifically ordered M10 formed hex screws with 16 mm width across flats will be

Basic thread lengths, B are the same as given in Table 18-47.

For additional manufacturing and acceptance speciﬁcations, reference should be made to the Standard.

Courtesy: American National Standards Institution, New York, USA (ANSI B18.2.3.2M-1979, R1989)

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TABLE 18-45

American National Standard metric heavy hex screws (ANSI B18.2.3.3M-1979, R1989)

screw Body diam, ﬂats, corners, height, height, face thickness, face diam,

and thread

M12 1:75 12.00 11.73 21.00 20.67 24.25 23.35 7.76 7.24 5.2 0.6 0.3 19.0 M14 2 14.00 13.73 24.00 23.67 27.71 26.75 9.09 8.51 6.2 0.6 0.3 22.0 M16 2 16.00 15.73 27.00 26.67 31.18 30.14 10.32 9.68 7.0 0.8 0.4 25.0 M20 2:5 20.00 19.67 34.00 33.00 39.26 37.29 12.88 12.12 8.8 0.8 0.4 31.0 M24 3 24.00 23.67 41.00 40.00 47.34 45.20 15.44 14.56 10.5 0.8 0.4 38.0 M30 3:5 30.00 29.67 50.00 49.00 57.74 55.37 19.48 17.92 13.1 0.8 0.4 46.0 M36 4 36.00 35.61 60.00 58.80 69.28 66.44 23.38 21.72 15.8 0.8 0.4 55.0

All dimensions are in millimeters

Basic thread lengths, B, are the same as given in Table 18-47.

Transition thread length, X, includes the length of incomplete threads and tolerances on the grip gaging length and body length It is intended for calculation purposes.

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TABLE 18-46

American National Standard metric hex ﬂange screws (ANSI/ASME B18.2.3.4M-1984)

Nominal

Basic thread lengths, B, are the same as given in Table 18-47.

Transition thread length, X, includes the length of incomplete threads and tolerances on grip gaging length and body length.

This dimension is intended for calculation purposes only.

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Lengths in parentheses are not recommended Recommended lengths of formed Hex Screws, Hex Flange Screws and Heavy Hex Flange Screws

do not extend above 150 mm Recommended lengths of Heavy Hex Screws do not extend below 20 mm Standard sizes for government use Recommended diameter-length combinations are indicated by the symbol Screws with lengths above cross lines are threaded full length.

b

Does not apply to Hex Flange Screws and Heavy Hex Flange Screws.

For available diameters of each type of screw, see respective dimensional table.

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TABLE 18-48

American National Standard Metric Hex Bolts (ANSI B18.2.3.5M-1979, R1989)

a

This size with width across flats of 15 mm is not standard Unless specifically ordered, M10 set bolts with 16 mmm width across flats will be furnished.

b

Basic thread length, B, is a reference dimension.

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TABLE 18-49

American National Standard Heavy Hex Bolts (ANSI B18.2.3.6M-1979, R1989)

Nominal Body diam, Width across ﬂats, Width across corners, Head height, Wrenching

a Basic thread lengths, B, are the same as given in Table 18-47.

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TABLE 18-50

Recommended clearance holes for metric hex screws and boltsa

Nominal Clearance hole diam, basic, Dh Nominal Clearance hole diam, basic, Dh

thread pitch Close Normal, preferred Loose thread pitch Close Normal, preferred Loose

a Does not apply to hex lag screws, hex socket headless screws, or round head square neck bolts.

b Applies only to heavy hex structural bolts.

Normal Clearance: This is preferred for general purpose applications and should be speciﬁed unless special design considerations dictate the need for either a close or loose clearance hole.

Close Clearance: This should be speciﬁed only where conditions such as critical alignment of assembled parts, wall thickness or other limitations necessitate use of a minimum hole When close clearance holes are speciﬁed, special provision (e.g countersinking) must be made at the screw used bolt entry side to permit proper seating of the screw or bolt head.

Loose Clearance: This should be speciﬁed only for applications where maximum adjustment capability between components being assembled is necessary.

Recommended Tolerances: The clearance hole diameters given in this table are minimum Recommended tolerances are: for screw or bolt diameter M5, þ0:2 mm; for M6 through M8, þ0:3 mm; for M20 through M24, þ0:4 mm; for M48 through M72, þ0:5 mm; and for M80 through M100, þ0:6 mm.

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TABLE 18-51

American National Standard metric hex screws and bolts—reduced body diameters

Metric Formed Hex Screws (ANSI B18.2.3.2M-1979, R1989) M5 0:8 5.00 4.82 4.46 4.36 3.5 2.5 M14 2 14.00 13.73 12.77 12.50 8.0 7.0 M6 1 6.00 5.82 5.39 5.21 4.0 3.0 M16 2 16.00 15.73 14.77 14.50 9.0 8.0 M8 1:25 8.00 7.78 7.26 5.04 5.0 4.0 M20 2:5 20.00 19.67 18.49 18.16 11.0 10.0 M10 1:5 10.00 9.78 9.08 8.86 6.0 5.0 M24 3 24.00 23.67 22.13 21.80 13.0 12.0

Metric Hex Flange Screws (ANSI B18.2.3.4M-1984) M5 0:8 5.00 4.82 4.46 4.36 3.5 2.5 M12 1:75 12.00 11.73 10.95 10.68 7.0 6.0 M6 1 6.00 5.82 5.39 5.21 4.0 3.0 M14 2 14.00 13.73 12.77 12.50 8.0 7.0 M8 1:25 8.00 7.78 7.26 7.04 5.0 4.0 M16 2 16.00 15.73 14.77 14.50 9.0 8.0

Metric Hex Bolts (ANSI B18.2.3.5M-1979, R1989) M5 0:8 5.48 4.52 4.46 4.36 3.5 2.5 M14 2 14.70 13.30 12.77 12.50 8.0 7.0 M6 1 6.48 5.52 5.39 5.21 4.0 3.0 M16 2 16.70 15.30 14.77 14.50 9.0 8.0 M8 1:25 8.58 7.42 7.26 7.04 5.0 4.0 M20 2:5 20.84 19.16 18.49 18.16 11.0 10.0 M10 1:5 10.58 9.42 9.08 8.86 6.0 5.0 M24 3 24.84 23.16 22.13 21.80 13.0 12.0

Metric Heavy Hex Bolts (ANSI B18.2.3.6M-1979, R1989) M12 1:75 12.70 11.30 10.95 10.68 7.0 6.0 M20 2:5 20.84 19.16 18.49 18.16 11.0 10.0 M14 2 14.70 13.30 12.77 12.50 8.0 7.0 M24 3 24.84 23.16 22.13 21.80 13.0 12.0

Metric Heavy Hex Flange Screws (ANSI B18.2.3.9M- 1984) M10 1:5 10.00 9.78 9.08 8.86 6.0 5.0 M16 2 16.00 15.73 14.77 14.50 9.0 8.0 M12 1:75 12.00 11.73 10.95 10.68 7.0 6.0 M20 2:5 20.00 19.67 18.49 18.16 11.0 10.0

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TABLE 18-53

Recommended diameter-length combinations for metric heavy hex structural bolts

Recommended diameter-length combinations are indicated by the symbol .

Bolts with lengths above the heavy cross lines are threaded full length.

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TABLE 18-54

American National Standard metric hex nuts, Styles 1 and 2 (ANSI B18.2.4.1M and B18.2.4.2M-1979, R1989)

and thread

Metric Hex Nuts—Style 1

a This size with width across flats of 15 mm is not standard Unless specifically ordered, metric hex nuts with 16 mm width across flats will be furnished.

18.74

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TABLE 18-55

American National Standard metric slotted hex nuts (ANSI B18.2.4.3M-1979, R1989)

Nominal nut ﬂats, corners, Thickness, face diam, thickness, of slot, face thickness,

a This size with width across flats of 15 mm is not standard Unless specifically ordered, M10 slotted hex nuts with 16 mm width across flats will be furnished.

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3 Black, P H., and O E Adams, Jr., Machine Design, McGraw-Hill Publishing Company, New York, 1955.

4 Baumeister, T., ed., Marks’ Standard Handbook for Mechanical Engineers, 8th ed., McGraw-Hill PublishingCompany, New York, 1978

5 Lingaiah, K., and B R Narayana Iyengar, Machine Design Data Handbook, Engineering College CooperativeSociety, Bangalore, India, 1962

6 Lingaiah, K., and B R Narayana Iyengar, Machine Design Data Handbook, Vol I (SI and Customary MetricUnits), Suma Publishers, Bangalore, India, 1986

7 Lingaiah, K., Machine Design Data Handbook, Vol II (SI and Customary Metric Units), Suma Publishers,Bangalore, India, 1986

8 Bureau of Indian Standards

16 Little, R E., Bolted Joints: How Much Give? Machine Design, Nov 9, 1967

17 Osgood, C C., Saving Weight on Bolted Joints, Machine Design, Oct 25, 1979

18 Bowman Distribution-Barnes Group, Fastener Facts, Cleveland, Ohio, 1985, p 90

19 American National Standards, ANSI B18.2.3.5M-1979, R1989

20 British Standards Institution, 2 Park Street, London, 1986

21 Machinery Handbook, 20th ed., 1999, Industrial Press, U.S.A

22 Shigley J E., and C R Mischke, Standard Handbook of Machine Design, McGraw-Hill Publishing CompanyNew York, 1996

23 Lingaiah, K., Machine Design Data Handbook, McGraw-Hill Publishing Company, New York, USA, 1994

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external area, m2(in2)

Ar radiating surface required, m2(in2)

Ac contact area of friction surface, m2(in2)

width of shoe, m (in)

width of inclined face in grooved rim clutch, m (in)

width of spring in centrifugal clutch, m (in)

width of wheel, m (in)

width of operating lever (Fig 19-16), m (in)

c heat transfer coeﬃcient, kJ/m2K h (kcal/m2/8C/h)

c1 speciﬁc heat of material, kJ/kg K (kcal/kg/8C)

c2 radiating factor for brakes, kJ/m2K s (kcal/m2/min/8C)

d diameter of shaft, m (in)

diameter of pin, roller pin, m (in)

d1 diameter of bolt, m (in)

diameter of pin at neck in the ﬂexible coupling, m (in)

d2 diameter of hole for bolt, m (in)

d0 outside diameter of bush, m (in)

D diameter of wheel, m (in)

diameter of sheave, m (in)

outside diameter of ﬂange coupling, m (in)

D1 inside diameter of disk of friction material in disk clutches and

brakes, m (in)

D2 outside diameter of disk of friction material in disk clutches and

brakes, m (in)

Di inside diameter of hollow rigid type of coupling, m (in)

Do outside diameter of hollow rigid type of coupling, m (in)

Dm mean diameter, m (in)

e1, e2, e3 dimensions shown in Fig 19-16, m (in)

E energy (also with suﬃxes), N m (lbf in)

Young’s modulus of elasticity, GPa (Mpsi)

Source: MACHINE DESIGN DATABOOK

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F operating force on block brakes, kN (lbf ); force at each pin in

the ﬂexible bush coupling, kN (lbf )total pressure, kN (lbf )

force (also with suﬃxes), kN (lbf )

actuating force, kN (lbf )

F1 tension on tight side of band, kN (lbf )

the force acting on disks of one operating lever of the clutch

(Fig 19-16), kN (lbf )

F2 tension on slack side of band, kN (lbf )

Fa0 total axial force on i number of clutch disks, kN (lbf )

Fb tension load in each bolt, kN (lbf )

Fc centrifugal force, kN (lbf )

Fn total normal force, kN (lbf )

Fx, Fy components of actuating force F acting at a distance c from the

hinge pin (Figs 19-25 and 19-26), kN (lbf )

F tangential force at rim of brake wheel, kN (lbf )

tangential friction force, kN (lbf )

g acceleration due to gravity, 9.8066 m/s2(9806.6 mm/s2)

(32.2 ft/s2)

h thickness of key, m (in)

thickness of central disk in Oldham’s coupling, m (in)

thickness of operating lever (Fig 19-16), m (in)

depth of spring in centrifugal clutch, m (mm)

H rate of heat to be radiated, J (kcal)

Hg heat generated, J (kcal)

Hd the rate of dissipation, J (kcal)

number of bolts,

number of rollers,

pairs of friction surfaces

number of shoes in centrifugal clutch

number of times the ﬂuid circulates through the torus in one

second

i1 number of driving disks

i2 number of driven disks

i0 number of operating lever of clutch

I moment of inertia, area, m4, cm4(in4)

kl load factor or the ratio of the actual brake operating time to the

total cycle of operation

l length (also with suﬃxes), m (in)

length of spring in centrifugal clutch measured along arc,

m (in)length of bush, m (in)

L dimension of operating lever as shown in Fig 19-16

Mt torque to be transmitted, N m (lbf in)

Mta allowable torque, N m (lbf in)

N normal force (Figs 19-25 and 19-26), kN (lbf )

N frictional force (Figs 19-25 and 19-26), kN (lbf )

p unit pressure, MPa (psi)

19.2 CHAPTER NINETEEN

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p unit pressure acting upon an element of area of the frictional

material located at an angle from the hinge pin (Figs 19-25and 19-26), MPa (psi)

maximum pressure between the fabric and the inside of the rim,

MPa (psi)

pa allowable pressure, MPa (psi)

maximum pressure located at an angleafrom the hinge pin

(Figs 19-25 and 19-26), MPa (psi)

pb bearing pressure, MPa (psi)

P total force acting from the side of the bush on operating lever

rm mean radius, m (in)

rmi mean radius of inner passage of hydraulic coupling, m (in)

rmo mean radius of outer passage in hydraulic coupling, m (in)

R reaction (also with suﬃxes), kN (lbf )

Rc radius of curvature of the ramp at the point of contact

(Fig 19-21), m (in)

Rd radius of the contact surface on the driven member (Fig 19-21),

m (in)

Rr radius of the roller (Fig 19-21), m (in)

Rx, Ry hinge pin reactions (Figs 19-25 and 19-26), kN (lbf )

t time of single clutching or braking operation (Eq 19-198), s

Ta ambient or initial temperature,8C (8F)

Tav average equilibrium temperature,8C (8F)

T rise in temperature of the brake drum,8C (8F)

tc cooling time, s (min)

v1, v2 speed of the live load before and after the brake is applied,

respectively, m/s

w axial width in cone brake, m (in)

width of band, m (in)

weight of the ﬂuid ﬂowing in the torus, kN (lbf )

weight lowered, kN (lbf )

weight of parts in Eq (19-136), kN (lbf )

weight of shoe, kN (lbf )

stress (also with suﬃxes), MPa (psi)

b allowable or design stress in bolts, MPa (psi)

0

b design bearing stress for keys, MPa (psi)

db design bending stress, MPa (psi)

shear stress, MPa (psi)

b allowable or design stress in bolts, MPa (psi)

d1 design shear stress in sleeve, MPa (psi)

d2 design shear stress in key, MPa (psi)

f design shear stress in ﬂange at the outside hub diameter, MPa (psi)

s design shear stress in shaft, MPa (psi)

one-half the cone angle, deg

pressure angle, deg

COUPLINGS, CLUTCHES, AND BRAKES 19.3COUPLINGS, CLUTCHES, AND BRAKES

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friction angle, deg

one-half angle of the contact surface of block, deg

factor which takes care of the reduced strength of shaft due to

keyway

!1 running speed of centrifugal clutch, rad/s

!2 speed at which the engagement between the shoe of centrifugal

clutch and pulley commences, rad/s

Other factors in performance or in special aspects are included from time to time

in this chapter and, being applicable only in their immediate context, are not

included at this stage

19.1 COUPLINGS

COMMON FLANGE COUPLING (Fig 19-1)

The commonly used formula for approximate

number of bolts

The torque transmitted by the shaft

The torque transmitted by the coupling

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The torque transmitted through bolts

The torque capacity which is based on bearing of

bolts

The torque capacity which is based on shear of ﬂange

at the outside hub diameter

The friction-torque capacity of the ﬂanged coupling

which is based on the concept of the friction force

acting at the mean radius of the surface

The preliminary bolt diameter may be determined by

the empirical formula

The bolt diameter from Eqs (19-2) and (19-4)

The bolt diameter from Eqs (19-3) and (19-4)

d1¼

ffiffiffiffiffiffiffiffiffiffiffiffiffiffi

d2s2ibD1

s

ð19-9Þ

d1¼

ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi8000P

i!bD1

s

SI ð19-10aÞ

FIGURE 19-1 Flange coupling.

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The diameter of shaft from Eqs (19-2) and (19-3)

The average value of diameter of the bolt circle

The hub diameter

The outside diameter of ﬂange

where d1, D1in m; P in kW; bin Pa;! in rad/s

d1¼

ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi1273P

in0D1b

s

SI ð19-10bÞwhere d1, D1in m; P in kW; bin Pa; n0in rps

d ¼ 3

ffiffiffiffiffiffiffiffiffiffiffiffiffi2546P

n0s

s

SI ð19-11dÞwhere P in kW; d in m; n0in rps

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The hub length

MARINE TYPE OF FLANGE COUPLING

Solid rigid type [Fig 19-2(a), Table 19-1]

The number of bolts

The diameter of bolt

FIGURE 19-2 Rigid marine coupling.

The thickness of ﬂange

The diameter of the bolt circle

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TABLE 19-1

Forged end type rigid couplings (all dimensions in mm)

Recessed Spigot diameter, Flange diameter, Recess Spigot diameter, size, diameter, Number ﬂange ﬂange Max Min D width, t D2 depth, c1 depth, c2 D1 d1 d2 H8 of bolts

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Hollow rigid type [Fig 19-2(b)]

The minimum number of bolts

The mean diameter of bolt

The empirical formula for thickness of ﬂange

The diameter of bolt circles

For design calculations of other dimensions of marine

hollow rigid type of ﬂange coupling

For dimensions of ﬁtted half couplings for power

transmission

PULLEY FLANGE COUPLING (Fig 19-3)

The number of bolts

The preliminary bolt diameter

FIGURE 19-3 Pulley ﬂange coupling.

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The width of ﬂange l1(Fig 19-3)

The hub length l

The thickness of the ﬂange

The hub diameter

The average value of the diameter of the bolt circle

PIN OR BUSH TYPE FLEXIBLE COUPLING

pb¼ bearing pressure, MPa (psi)

F ¼ force at each pin, kN (lbf ) ¼ pbld0

d0¼ outside diameter of the bush, m (in)

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Shear stress in pin

Bending stress in pin

OLDHAM COUPLING (Fig 19-5)

The total pressure on each side of the coupling

The torque transmitted on each side of the coupling

Power transmitted

The diameter of the disk

The diameter of the boss

p¼ F

0:785d2 p

ð19-34Þwhere

p¼ allowable shearing stress, MPa (psi)

dp¼ d1¼ diameter of pin at the neck, m (in)

b¼F

l

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Length of the boss

Breadth of groove

The thickness of the groove

The thickness of central disk

MUFF OR SLEEVE COUPLING (Fig 19-6)

The outside diameter of sleeve

The outside diameter of sleeve is also obtained from

equation

The length of the sleeve (Fig 19-6)

Length of the key (Fig 19-6)

The diameter of shaft

d

s

ð19-49Þwhere Mtis torque obtained from Eq (19-2)

FIGURE 19-5 Oldham’s coupling.

FIGURE 19-6 Muﬀ or sleeve coupling.

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The width of the keyway

The thickness of the key

FAIRBAIRN’S LAP-BOX COUPLING

(Fig 19-7)

The outside diameter of sleeve

The length of the lap

The length of the sleeve

FIGURE 19-7 Fairbairn’s lap-box coupling.

SPLIT MUFF COUPLING (Fig 19-8)

The outside diameter of the sleeve

The length of the sleeve (Fig 19-8)

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The torque to be transmitted by the coupling

SLIP COUPLING (Fig 19-9)

The axial force exerted by the springs

With two pairs of friction surfaces, the tangential

force

The radius of applications of F with suﬃcient

accuracy

The torque

The relation between D1and D2

FIGURE 19-9 Slip coupling.

l ¼ 3:5d or 2:5d þ 2:0 USCS ð19-55bÞwhere l, d in in

D2

D1

where D1and D2are the inner and outer diameters

of disk of friction lining

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