Day 5 - Roller Chain & Sprocket, Belts, Bearings

Roller Chain & Sprocket: Designation (RCXY)

RC = Roller Chain

X → Pitch = 1/8 X ; inches

Y = 0 usual proportion = 1 lightweight = 5 roller-less

Roller Chain & Sprocket: Designation Silent Chain

SCXY ; wherein Silent Chain = Inverted Tooth

Roller Chain & Sprocket: Subscript Numbering Designation

1 = smaller sprocket

2 = larger sprocket

Roller Chain & Sprocket: Estimation formula for the Chain Pitch

p = pitch in inches

N = speed in rpm

Roller Chain & Sprocket: Sprocket Teeth (pitches up to 1 inch)

d = bore in inches

p = pitch in inches

Roller Chain & Sprocket: Sprocket Teeth (pitches up to 1.25 to 2.5 inch)

d = bore in inches

p = pitch in inches

Roller Chain & Sprocket: Sprocket Teeth (Silent Chain)

d = bore in inches

p = pitch in inches

Roller Chain & Sprocket: Angle between two adjacent teeth of sprocket

θ = 360 / T

Roller Chain & Sprocket: Pitch Diameter

p = pitch

N = speed

D1 = pitch diameter of smaller sprocket

D2 = pitch diameter of larger sprocket

T1 = teeth of smaller sprocket

T2 = teeth of larger sprocket

θ = angle between two adjacent teeth

Roller Chain & Sprocket: Pitch Line Velocity

p = pitch

N = speed

D1 = pitch diameter of smaller sprocket

D2 = pitch diameter of larger sprocket

T1 = teeth of smaller sprocket

T2 = teeth of larger sprocket

θ = angle between two adjacent teeth

Roller Chain & Sprocket: Power Transmitted

F = force

V = velocity

T = torque

N = speed

Roller Chain & Sprocket: Length of Chain in pitches

Lp = length in pitches

Cp = center distance in pitches

T2 = teeth in larger sprocket

T1 = teeth in smaller sprocket

Roller Chain & Sprocket: Length of Chain in pitches to Length in Inches

Lp = length in pitches

L = length in inches

p = pitch in inches

Roller Chain & Sprocket: Center Distance in pitches to Center Distance in Inches

Roller Chain & Sprocket: Average Good Center Distance (Standard)

C = D2 + D1/2

Roller Chain & Sprocket: Horsepower Capacity based on Link Plate Fatigue Strength

Roller Chain & Sprocket: Horsepower Capacity based on Silent Chain

Roller Chain & Sprocket: Width of Chain

Roller Chain & Sprocket: Design HP

Design HP = Given HP x Service Factor

Service Factor = 1 if not given

Roller Chain & Sprocket: Number of Strands

Belts: Subscript Numbering Designation

1 = smaller pulley

2 = larger pulley

Belts: Open - Diameter and Speed Relation

Belts: Open - Belt Length

Belts: Open - Angle of Contact or Wrap Angle

(-) = smaller pulley

(+) = larger pulley

Belts: Open - Alpha

Belts: Crossed - Belt Speed and Diameter Relation

Belts: Crossed - Belt Length

Belts: Crossed - Angle of Contact or Wrap Angle

Belts: Crossed - Alpha

Belts: Open or Crossed - When there is %slip

Belt Tension: Centrifugal Tension is Neglected

F1 = tension in tight side

F2 = tension in slack side

f = coefficient of friction

θ = arc of contact in radians

F1 > F2

Belt Tension: Maximum Tension on Belt

Sd = belt design stress

b = width

t = thickness

Belt Tension: Belt Design Stress

Sd = 400 e

Sd = belt design stress in PSI

e = joint efficiency

Belt Tension: Joint Efficiency

e = 1 for cemented joint = 0.88 wirelace ends = 0.35 ends joined by metal hooked

Belt Tension: Centrifugal Tension is Considered

Belt Tension: Centrifugal Tension

Fc = centrifugal tension

p = belt density

v = belt velocity

b = belt width

t = belt thickness

Belt Tension: Net Belt Pull

Belt Tension: Stress in Belt

Sw = working stress

F1 = tension in tight side

b = belt width

t = belt thickness

Belt Tension: Working Stress for Leather Belts

Sw = 300 PSI for leather belts

Belt Tension: Power Transmitted

Belt Tension: Torque

Belt Tension: When to determine if to consider or not Centrifugal Tension

If specific weight of belt is given, consider Centrifugal Tension

Belt Tension: Density of leather, rubber, and balata belts

V-Belt: Designation (B75)

B = Type

75 = Nominal Length in inches (Ln)

V-Belt: Designation (SPB 1950)

B = Type

1950 = Pitch Length in mm

V-Belt: Pitch Length from Designation

Lp = pitch length

Ln = nominal length

x = type factor

V-Belt: Type Factor (x)

Type A: x = 1.3

Type B: x = 1.8

Type C: x = 2.9

Type D: x = 3.3

x in inches

V-Belt: Belt Length

V-Belt: Center Distance

L = pitch length of belt

C = center distance

D2 = pitch diameter of large pulley

D1 = pitch diameter of small pulley

V-Belt: b

V-Belt: Arc of Contact on Small and Large Sheave

Bearings: Units of Dynamic Viscosity

Bearings: Diametral Clearance

D = diameter (bore) of bearing

d = diameter of the journal

Bearings: Radial Clearance

D = diameter (bore) of bearing

d = diameter of the journal

Bearings: Diametral Clearance Ratio

Bearings: Bearing Pressure

Fr = radial load

L = length of journal inside bearing

D = diameter of bearing

Bearings: Bearing Modulus = Bearing Characteristic Number

BCN = unitless

μ = viscosity in reyns = psi-sec

N = speed in radians / second

P = pressure or unit loading in psi

Bearings: BCN if speed changes

Bearings: Frictional Torque (Vallance)

F = force in lbs

fb = bearing friction

D = diameter (bore) of bearing

Bearings: Frictional Torque (Faires)

Tf = frictional torque in lb-in

u = viscosity in reyns

r = journal radius in inch

L = axial length of bearing in inch

ns = journal speed in radians per second

Cr = radial clearance in inch

Bearings: Heat Dissipated (Vallance)

H = heat dissipated in BTU/min

Ch = heat dissipation coefficient of projected area in lb-ft/min-in²

L = length of bearing in inches

D = diameter of bearing in inches

Bearings: Heat Radiating Capacity

Hd = heat radiating capacity in BTU / in² or lb-ft/min-in²

N = speed in rpm

T = torque in lb-ft

L = length in inch

D = diameter in inch

Bearings: Heat Radiating Capacity (Axel K. Pedersen)

Hd = heat radiating capacity in BTU / in² or lb-ft/min-in²

To = operating temperature of bearing in F

Ta = ambient temperaeture of surrounding air in F

k = construction constant

Bearings: Construction Constant (Axel K. Pedersen)

k = 31 (heavy duty)

k = 55 (light duty)