Chapter 13 : Transmission of motion and power

Example 13.1 pg : 27

In [1]:
# Variables
N1 = 250.;
D1 = 53.;
D2 = 32.;

# Calculations
N2 = N1*(D1/D2);

# Results
print 'Speed of shaft: %2.2f RPM'%(N2);

Speed of shaft: 414.06 RPM

Example 13.2 pg : 27

In [3]:
# Variables
D1 = 600.;
D2 = 300.;
N1 = 100.;
VR = D1/D2;
N2 = VR*N1;

# Calculations and Results
print 'Case One ';
print 'Velocity Ratio =  %2.2f'%(VR);

print 'Speed of driven shaft =  %2.2f RPM'%(N2);


print 'Case Two ';
VR = (D1+5)/(D2+5);
N2 = VR*N1;
print 'Velocity Ratio =  %2.2f'%(VR);

print 'Speed of driven shaft =  %2.2f RPM'%(N2);


print 'Case Three ';
S = 4.;
VR = ((D1+5)/(D2+5))*((100-S)/100.);
N2 = VR*N1;
print 'Velocity Ratio =  %2.2f'%(VR);

print 'Speed of driven shaft =  %2.2f RPM'%(N2);

Case One 
Velocity Ratio =  2.00
Speed of driven shaft =  200.00 RPM
Case Two 
Velocity Ratio =  1.98
Speed of driven shaft =  198.36 RPM
Case Three 
Velocity Ratio =  1.90
Speed of driven shaft =  190.43 RPM

Example 13.3 pg : 28

In [7]:
# Variables
D1 = 0.3;
D2 = 0.2;
C = 3.;

# Calculations
L1 = ((22./7)*(1./2)*(D1+D2))+(((D1+D2)**2)/(4*C))+(2*C);
L2 = ((22./7)*(1./2)*(D1+D2))+(((D1-D2)**2)/(4*C))+(2*C);
L = L2-L1;

# Results
print 'The belt length is to be reduced by %2.4f mm'%((-L)*1000);

# note : answer is differ because of rounding off error. check.

The belt length is to be reduced by 20.0000 mm

Example 13.4 pg : 28

In [8]:
import math 

# Variables
D = 1.;
P = 5000.;
N = 250.;
Mew = 0.25;
PP = 20.;
Theta = 170*(22./7)*(1./180);
V = ((22./7)*D*N)/60;

# Calculations
T12 = math.exp(Mew*Theta)-1;
T2 = (P/(V*T12));
T1 = (T12+1)*T2;
W = T1/PP;

# Results
print 'Width of belt =  %2.2f mm'%(W);

Width of belt =  36.44 mm

Example 13.5 pg : 29

In [9]:
# Variables
N1 = 1000.;
Z1 = 30.;
Z2 = 45.;
Z3 = 75.;

# Calculations
N13 = Z3/Z1;
N3 = N1/N13;

# Results
print 'Velocity Ratio of gear train =  %2.1f '%(N13);
print 'N3 =  %2.1f RPM'%(N3);

Velocity Ratio of gear train =  2.5 
N3 =  400.0 RPM

Example 13.6 pg : 30

In [10]:
# Variables
Na = 600.;
Za = 25.;
Zb = 50.;
Zc = 20.;
Zd = 40.;

# Calculations
Nad = (Zb/Za)*(Zd/Zc);
Nd = Na/Nad;

# Results
print 'Speed of Output Shaft =  %2.1f RPM'%(Nd);

Speed of Output Shaft =  150.0 RPM