Hydraulic Formulas for Motors and Pumps
Hydraulic Formulas for Motors and Pumps: Essential Calculations for Optimal Performance
Although motors and pumps can look similar, they do different jobs in a hydraulic system. Pumps use an external power source (engine or electric motor) to create flow, while a hydraulic motor converts that pressurised flow into rotational force.
What these formulas help you calculate
- Displacement (cc/rev)
- Motor speed (rpm)
- Torque (Nm)
- Hydraulic power (kW)
- Flow rate (L/min)
Key Differences Between Hydraulic Motors and Pumps
Purpose and energy conversion
- Hydraulic pumps convert mechanical energy into hydraulic energy (flow/pressure).
- Hydraulic motors convert hydraulic energy into mechanical energy (rotary motion).
Below are some essential hydraulic formulas for motors & pumps to help calculate performance metrics such as displacement, torque, speed, and power.
1) Displacement (cm³/rev or cc/rev)
- D = Displacement (cm³/rev)
- Q = Flow rate (L/min)
- N = Motor speed (rpm)
2) Motor speed (rpm)
- N = Speed (rpm)
- Q = Flow rate (L/min)
- D = Displacement (cm³/rev)
3) Torque (Nm)
- T = Torque (Nm)
- D = Displacement (cm³/rev)
- ΔP = Pressure drop across motor (bar)
4) Hydraulic power (kW) from torque & speed
- P = Power (kW)
- T = Torque (Nm)
- N = Speed (rpm)
5) Hydraulic power (kW) from flow & pressure
- Ph = Hydraulic power (kW)
- Q = Flow rate (L/min)
- ΔP = Pressure difference (bar)
6) Flow rate (L/min)
- Q = Flow rate (L/min)
- D = Displacement (cm³/rev)
- N = Speed (rpm)
Flowfit can help with hydraulic motor & pump calculations
If you’re unsure about sizing, performance calculations, or selecting the right components, our Technical Sales team can help you choose the best solution for your system. Get in touch for expert advice.
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