Chapter 5: Valve Diagrams and Valve Gears

Example 1, Page 147

In [9]:
import math

#Variable declaration
s=1.125#inch
e=0.25#inch
t=2.25#inch
alpha=35#degrees

#Calculations
#from 5.2, we know theta+alpha=sininverse(s/t)
x=math.degrees(math.asin(s/t))
y=180-x#sin(x)=sin(180-x)=sin(y)
#at admission
p=x-alpha
#at cutoff
q=y-alpha
#from 5.3, theta+alpha=sininnverse(-e/t)
ang=math.degrees(math.asin(-e/t))
angle=abs(ang)
a=180+angle#lies in the negative region of sine curve
b=360-angle#lies in hte negative region of sine curve
#at release
r=a-alpha
#at compression
s=b-alpha

#Results
print "Angle theta at admission, cut-off,release and compression are %.2f, %.2f, %.2f and %.2f degrees respectively"%(p,q,r,s)
Angle theta at admission, cut-off,release and compression are -5.00, 115.00, 151.38 and 318.62 degrees respectively