MPP Formulas for PTOs and Hydraulics

TO SOLVE FOR CALCULATOR ENTRY*
PTO Output Speed PTO RPM = ENGINE RPM x PTO%
Required Engine Speed ENGINE RPM = DESIRED PTO RPM ÷ PTO%
Horsepower HP = T X RPM ÷ 5252
Torque T = HP X 5252 ÷ RPM
Area of a Circle A = πr2 or A = d2 X .7854
Volume of a Cylinder V = πr2 X Li ÷ 231 or d2 X .7854 X Li ÷ 231
Force of a Cylinder F = A X PSI
Cylinder Extension (inches/second) EXT. RATE = GPM X 4.9 ÷ d2
Cylinder Extension (time to extend) EXT. TIME = CYL. VOLUME X .26 ÷ GPM
Volume of a Reservoir (rectangular) VOL = Li X Wi X Di ÷ 231
Volume of a Reservoir (round) VOL = πr2 X Li ÷ 231 or d2 X .7854 X Li ÷ 231
Pump Output Horsepower HP = GPM X PSI ÷ 1714
Pump Input Horsepower HP = GPM X PSI ÷ 1714 ÷ E
Pump Input Torque (ft.lb.) T = CID X PSI ÷ 2π
Pump Output Flow GPM = CIR X RPM ÷ 231 X E
Pump Input Speed RPM = GPM X 231 ÷ CIR ÷ E
Displacement of Pump CIR = GPM X 231 ÷ RPM ÷ E
Flow in GPM using PTO GPM = ENGINE RPM x
PTO% X CIR ÷ 231 X E
Velocity of Oil V = GPM X .3208 ÷ A
Heat Rise in Degrees F ΔF° = HP X 746 X Inefficiency X Minutes ÷ Gallons in system ÷ 60
The following hydraulic motor formulas are calculated in inch pounds (in.lb) rather than foot pounds. To convert to ft.lb divide by 12.
Motor Output Torque
Continuous Tc = GPM X PSI X 36.77 ÷ RPM or
Tc = CID X PSI ÷ 2 π or
Tc = HP X 63025 ÷ RPM
Starting Ts = Tc X 1.3
Accelerating Ta = Tc X 1.1
Motor Working Pressure T X 2 π ÷ CIR ÷ E
Motor RPM RPM = GPM X 231 ÷ CIR
* CONVERSION CHART
From English Units (US) to
Système International (metric)
T= Torque (ft. lb.)
A= Area of circle (sq.in.)
F= Force
d= diameter
r= radius
π= 3.1416 (pi)
Li= Length (inches)
Wi= Width (inches)
Di= Depth (inches)
VOL= Volume
E= Efficiency
CIR= Cubic Inches/Revolution
V= Velocity

1 Gallon = 231 cu.in.
From To Multiply by or Divide by
Cu.in. (in3) CC (cm3) 16.39 0.06102
Cu.in. (in3) Liters 0.01639 61.02
Pounds Feet (lb.ft.) Newton Meters (Nm) 1.356 0.7376
Gallons Liters 3.785 0.2642
Horsepower BTU 2545 0.00093
Horsepower Watts 746 0.001341
Horsepower KW 0.7457 1.341
PSI Bar 0.06804 14.5
PSI KiloPascal (KPa) 6895 0.000145
Pound Kilogram 2.2 0.4545
Inch Millimeter (MM) 25.4 0.03937
Mile Kilometer (KM) 1.6093 0.6214
© 2002 PTO teknikk.