Hydraulic Power

on . Posted in Fluid Dynamics

Hydraulic Power, abbreviated as \(P_h\), is generated through a combination of oil flow and pressure.  Oil flow and pressure is created from a hydraulic pump and transmitted through hoses or tubes, via control valves, to the hydraulic motor or cylinder that will do the work.  Hydraulic power has an advantage in that the space required is considerably less than that for conventional drives.  This technology relies on the principles of fluid dynamics and Pascal's law, which states that a change in pressure applied to an enclosed fluid is transmitted undiminished to all portions of the fluid and to the walls of its container.

Hydraulic Power Index

In a hydraulic system, a pump is used to pressurize hydraulic fluid (usually oil), and this pressurized fluid is then transmitted through a network of pipes or tubes to various hydraulic components, such as cylinders or motors.  The pressurized fluid is used to perform work, such as lifting heavy loads, turning a shaft, or moving machinery.

Common components of a hydraulic system

  • Hydraulic Pump  -  This is responsible for generating the flow of hydraulic fluid by converting mechanical power into fluid power.
  • Hydraulic Fluid  -  Typically, oil is used as the hydraulic fluid because it is incompressible and can transmit force effectively.
  • Cylinders  -  These are devices that use the hydraulic fluid to produce linear motion.  They consist of a cylindrical chamber and a piston, and when fluid pressure is applied, it causes the piston to move, generating mechanical force.
  • Hydraulic Motors  -  These devices use hydraulic pressure to generate rotary motion.  They are often used in applications where rotational motion is required.
  • Valves  -  Valves control the flow of hydraulic fluid within the system.  They can start, stop, or change the direction of fluid flow.

Hydraulic power is used in various applications, including industrial machinery, construction equipment, aerospace systems, and automotive systems.  It is valued for its ability to transmit high levels of force, control precision, and operate in diverse environments.


Hydraulic Power formula

\( P_h = \dot m_f \; g \; h \)     (Hydraulic Power)

\( \dot m_f =  P_h \;/\; g \; h \)

\( g =  P_h \;/\; \dot m_f \; h \)

\( h =  P_h \;/\; \dot m_f \; g \)

Symbol English Metric
\( P_h \) = hydraulic power \(lbm-ft^2 \;/\; sec\) \(kg-m^2 \;/\; s\)
\( \dot m_f \) = water mass flow rate \(lbm \;/\; sec\) \(kg \;/\; s\)
\( g \) = gravitational acceleration \(ft \;/\; sec^2\) \(m \;/\; s^2\)
\( h \) = hydraulic head \(in\) \(m\)


Hydraulic Power formula

\( P_h = \rho_w \; Q \; g \; h \)     (Hydraulic Power)

\( rho_w =   P_h \;/\; Q \; g \; h \)

\( Q =  P_h \;/\; \rho_w \; g \; h \)

\( g =  P_h \;/\; \rho_w \; Q \; h \)

\( h =  P_h \;/\; \rho_w \; Q \; g \)

Symbol English Metric
\( P_h \) = hydraulic power  \(lbm-ft^2 \;/\; sec\)  \(kg-m^2 \;/\; s\) 
\( \rho_w \)   (Greek symbol rho) = water density by temperature \(lbm \;/\; ft^3\) \(kg \;/\; m^3\)
\( Q \) = water volumetric flow rate \(ft^3 \;/\; sec\) \(m^3 \;/\; s\)
\( g \) = gravitational acceleration \(ft \;/\; sec^2\) \(m \;/\; s^2\)
\( h \) = hydraulic head \(in\) \(m\)


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Tags: Hydraulic Power