Hydraulic Calculators

IMPORTANT: The information provided has been carefully checked and is given in good faith, but users should take the necessary steps to ensure the accuracy and relevance to their specific requirements. Sunfab Hydraulics AB, do not accept any liability for injury, damage or unsatisfactory operation resulting from the construction or use of any machines designed using this information.

Units

Unit Converter. Enter device value.

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Please note! When we suggest standard values, this gives you a very close approximation that is good enough for general use. You can of course also enter the actual values instead of the standard values.


Measurements and units used

Torque
T Nm
Differential pressure * Δp Bar
Speed n rpm
Geometr. displacement volume per rotation Vg cm³/rpm

* Δp diffrence between port 1 and port 2 on hydraulic motors.

Power P kW
Flow qv L/min
Mechanical hydraulic efficiency ** ηmh 0.9 - 0.95
Total efficiency ηt 0.8 - 0.9

** NOTE! At pressures below 100-150 bar, hydraulic mechanical efficiency curves should be used for hydraulic motors.

SCM Efficiency curves

Hydraulic pumps

1. What displacement do we get?

If you know flow (l/min) and speed (rpm)

V=  geometric displacement volume cm³/rpm

l/min
rpm
(Standard value ca. 0.93-0.98)
cm³/revolution

2. What displacement do we get?

If you know torque (Nm) and system pressure (bar)

V=  geometric displacement volume cm³/rpm

Nm
Bar
(Standard value ca. 0.9-0.95)
cm³/rpm

3. What flow do we get?

If you know displacement (cm³/rpm) and speed (rpm)

q= Flow in l/min

cm³/rpm
rpm
(Standard value ca. 0.93-0.98)
l/min

4. What speed do we get?

If you know flow (l/min) and displacement (cm³/rpm)

n = Speed in rpm

l/min
cm³/revolution
(Standard value ca. 0.93-0.98)
rpm

5. What torque do we get?

If you know displacement (cm³/rpm) and system pressure (bar)

T = Torque in Nm

cm³/rpm
Bar
(Standard value ca. 0.9-0.95)
Nm

6. What power do we get?

If you know flow (l/min) and system pressure (bar)

P = Power in kW

l/min
Bar
(Standard value ca. 0.8-0.9)
kW

Hydraulic motors

1. What flow do we get?

If you know displacement (cm³/rpm) and speed (rpm)

q= Flow in l/min

cm³/rpm
rpm
(Standard value ca. 0.93-0.98)
l/min

2. What flow do we get?

If you know power (kW) and differential pressure (bar)

q= Flow in l/min

kW
Bar
(Standard value ca. 0.8-0.9)
l/min

3. What displacement do we get?

If you know flow (l/min) and displacement (cm³/rpm)

V= geometric displacment volume cm³/rpm

l/min
rpm
(Standard value ca. 0.93-0.98)
cm³/rpm

4. What displacement do we get?

If you know power (kW) and differential pressure (bar)

V= geometric displacment volume cm³/U

Nm
Bar
(Standard value ca. 0.9-0.95)
cm³/rpm

5. What rpm do we get?

If you know flow (l/min) and displacement (cm³/rpm)

n = Speed in rpm

l/min
cm³/rpm
(Standard value ca. 0.93-0.98)
rpm

6. What rpm do we get?

If you know power (kW) and torque (Nm)

n = Speed in rpm

kW
Nm
rpm

7. What torque do we get?

If you know displacement (cm³/rpm) and differential pressure (bar)

T = Torque in Nm

cm³/rpm
Bar
(Standard value ca. 0.9-0.95)
Nm

8. What torque do we get?

If you know power (kW) and speed (rpm)

T = Torque in Nm

kW
rpm
Nm

9. What differential pressure do we get?

If you know torque (Nm) and displacement (cm³/rpm)

Δp = Differential pressure in bar

Nm
cm³/rpm
(Standard value ca. 0.9-0.95)
Bar

10. What differential pressure do we get?

If you know power (kW) and flow (l/min)

Δp = Differential pressure in bar

kW
l/min
(Standard value ca. 0.8-0.9)
Bar

11. What power do we get?

If you know torque (Nm) and speed (rpm)

P = Power in kW

Nm
rpm
kW

12. What power do we get?

If you know differential pressure (bar) and flow (l/min)

P = Power in kW

Bar
l/min
(Standard value ca. 0.8-0.9)
kW