# Chapter No 9 : Hydraulic motors

### Example9.1 Page No 194

In [1]:
import math

#Variable initialization
P=2000.0            #lbf/in^3 pressure
Vm=0.5              #in^3  displacement

#CALCULATONS
T=P*Vm*0.16

#RESULTS
print('\n Theotrical torque = %.3f lb-in ' %T)

 Groove diameter = 3.776 in

Groove width = 0.196 in

outside diameter = 4.000 in 

### Example 9.2 Page No 194

In [9]:
import math

#Variable initialization
Q=7.5        #gpm flow rate
Q2=28.39     #l/min f;ow rate
Vm=2         #in^3 displacement
Vm2=0.03281  #l/rev displacement

#CALCULATIONS
N=231.0*Q/Vm    # Theotrical speed
#SI units
N2=(Q2/Vm2)     # in SI units Theotrical speed

#RESULT
print(' Theotrical speed of fluid power = %.3f rpm ' %N)
print(' Using SI units Theotrical speed of fluid power = %.3f rev/min ' %N2)

 Theotrical speed of fluid power = 866.250 rpm
Using SI units Theotrical speed of fluid power = 865.285 rev/min


### Example 9.3 Page No 195

In [1]:
import math

#Variable initialization
Vm=0.55             #in^3 displacement
N=3400.0            #rpm Theotrical speed

#CALCULATIONS
Q=Vm*N/231.0

#RESULT
print(' Effective flow rate = %.3f gpm ' %Q)

 Effective flow rate = 8.095 gpm


### Example 9.4 Page No 195

In [2]:
import math

#Variable initialization
T=32.0              #lb_ft torque
N=1200.0            #rpm Theotrical speed
P=2000.0            #psi pressure lbf/in^2
Q=7.5               #gpm flow rate

#CALCULATIONS
eo=T*N*100.0/(P*Q*3.06)

#RESULT
print(' Overall efficiency = %.3f percent ' %eo)

 Overall efficiency = 83.660 percent


### Example 9.5 Page No 196

In [12]:
import math

#Variable initialization
Vm=0.6              #in^3 displacement
N=2400              #rpm theotrical speed
Qa=6.5              #gal/min flow rate
Vm1=0.00981         #l/rev  displacement
#CALCULATIONS
ev=((Vm*N)/(Qa*231))*100
#in SI units
ev1=((Vm1*N)/(24.611))*100
TFL=0.041*Qa                  # total fluid loss
CDL=0.50*TFL                  #Case drain loss

#RESULT
print(' Total fluid loss = %.2f gal/min ' %TFL)
print(' Case drain loss  = %.2f gal/min ' %CDL)
print(' Volumetric efficiency = %.2f percent ' %ev)
print(' Volumetric efficiency in SI units = %.2f percent ' %ev1)

 Total fluid loss = 0.27 gal/min
Case drain loss  = 0.13 gal/min
Volumetric efficiency = 95.90 percent
Volumetric efficiency in SI units = 95.66 percent


### Example 9.6 Page No 197

In [2]:
import math

#Variable initialization
eo=88.0          # Overall efficiency (%)
ev=97            # Volumetric efficiency(%)

#CALCULATIONS
em=(eo/ev)*100

#RESULT
print(' Mechnical efficiency efficiency = %.3f percent ' %em)

 Mechnical efficiency efficiency = 90.722 percent