Gear Pump Division
Standard Truck Pump Training
Basic Pump and Motor
Formulas
Pump Formulas
Glossary of Terms
CID = [GPMX231] / RPM
GPM = [RPM X CID] / 231
T = [CID X PSI] / 75.36
T = [HP X 5252] / RPM
CID = Cubic Inches Displaced
GPM = Gallons Per Minute
231 = Number of Cubic Inches in a Gallon
RPM = Revolutions Per Minute
T = Torque
75.36 = 24 X 3.14
HP = Horse Power
5252 = Constant Number Used to
determine HP
Motor Formulas
RPM = [GPM X 231] / CID
CID = [GPM X 231] / RPM
T = [CID X PSI] / 75.36
T = [HP X 5252] / RPM
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Where to Find Standard Truck Pumps
Gear Pump Division
Vocational Truck Program
Program Features
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Most Popular Truck
Pumps
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Quick Delivery
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Competitive Pricing
Purchased one at a
time
Listed by type giving
CID on all pumps
for determining size
required
Click on Picture To View
Find a Pump
Example How to Find
Big Man’s refuse company needs a pump for a moving floor. The
pump needs to generate 27 gpm’s at a 1000 rpms. The moving floor
will not see above 2500 psi maximum pressure. The customer wants
O-Ring ports through the rear and wants to direct mount the pump to
a 7/8” 13 Tooth PTO shaft. What is the CID required for this
application? What Pumps do you have to choose from?
1st Solve for CID. CID = [GPM X 231] / RPM
CID = [27 X 231] / 1000 = 6237 / 1000 = 6.237 CID
2nd Find a Pump in the Vocational Truck Pump Catalog that
matches close to 6.237 CID
Possible Answers: Note All Answers will work below
• 3159310016T
• 3139610526T
• 3139610766T
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Find a Pump
Example How to Find
Big Rig Truck needs a dump pump for a
dump trailer application. The customer
wants 27 gpm at 1000 rpm’s and wants
to direct mount the pump that has the
air shift already installed on a Chelsea®
489 PTO with a 7/8” 13 Tooth shaft. The
pump must turn CCW.
1st Solve for CID
CID = GPM X 231 / RPM
CID = [27 X 231] / 1000 6237 / 1000 = 6.237 CID
2ND Find a pump from the vocational truck pump
catalog find a dump pump that is close to 6.237
CID.
Answer
• 3149325227T
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