Chapter19-Plain Surface Bearings

Ex1-pg417

import math

print('MACHINE DESIGN \n Timothy H. Wentzell, P.E. \n EXAMPLE-19.1 Page No.417\n');

##Length
F=20.;
n=500.;
PV=3000.;
L1=math.pi*F*n/(12.*PV);

##Use 7/8-inch or longer bearing

L=7./8.;

print'%s %.2f %s '%('\n Length of bearing = ',L,' in.');

##Maximum pressure
A=(3./4.)*(7./8.);
P=F/A;

print'%s %.2f %s '%('\n Maximum pressure = ',P,' lb/in^2.');

##Maximum velocity
D=3/4.;
V=math.pi*D*n/12.;

print'%s %.2f %s '%('\n Maximum velocity = ',V,' ft/min.');

MACHINE DESIGN 
 Timothy H. Wentzell, P.E. 
 EXAMPLE-19.1 Page No.417


 Length of bearing =  0.88  in. 

 Maximum pressure =  30.48  lb/in^2. 

 Maximum velocity =  98.17  ft/min. 

Ex2-pg421

import math

print('MACHINE DESIGN \n Timothy H. Wentzell, P.E. \n EXAMPLE-19.2 Page No.421\n');

##Life in hours of operation
t=0.01;
K=12*10**-10;
P=30.5;
V=98.;
T=t/(K*P*V);

print'%s %.2f %s '%('\n Life = ',T,' hours.');

##Note-There is an error in the answer given in textbook

MACHINE DESIGN 
 Timothy H. Wentzell, P.E. 
 EXAMPLE-19.2 Page No.421


 Life =  2788.00  hours.