Fluid power is the technology that deals with the generation, control, and transmission of pressurized fluids.

As the term fluid refers either to gases or to liquids, fluid power is also subdivided into the categories of hydraulics and pneumatics. The differences being that with hydraulics the medium used is a liquid (ie mineral oil or water) and for pneumatics it is a gas (ie air or another inert gas). A fluid is defined as a substance that continually deforms (flows) under an applied shear stress regardless of the magnitude of the applied stress. ... Table of Hydraulics and Hydrostatics, from the 1728 Cyclopaedia. ... Table of Pneumaticks, 1728 Cyclopaedia Pneumatics, from the Greek πνευματικός (pneumatikos, coming from the wind) is the use of pressurized gases to do work in science and technology. ...

Practical use

In practice fluid power is used to achieve one of two generic tasks:

Transport fluid
Delivering the fluid from one location to another to achieve a useful purpose.
An example of this in the case of hydraulics in a lube oil or grease system to provide oil or grease to lubricate bearings on heavy equipment.

Transport energy
In this case the fluid flow is used to actuate a device specifically designed to operate from the flow provided. In general, these actuators fall into the following categories: An actuator is the mechanism by which an agent acts upon an environment. ...

• Cylinder (hydraulic or pneumatic): Provides force in a linear fashion
• Motor(hydraulic or pneumatic): Provides continuous rotational motion
• Rotary actuator: Provides rotational motion of less than 360 degrees.

can be described as fluid motors either a cylinder (providing a linear output force/motion) or motor (providing a continuos rotary output) or a rotary actuator which provides rotary output limited to less than 360 degrees. This page is a candidate for speedy deletion. ... Air cylinder can also mean a gas cylinder used to store compressed air, often used for scuba diving. ... The hydraulic cylinders on this excavator control the machines linkages. ... A pneumatic motor is a machine which converts energy of compressed air into mechanical motion; for example a pneumatic vane motor or pneumatic piston motor. ...

Application

Hydraulics and pneumatics are similar in many ways, but there are clear reasons for using one over the other.

• Cost: Pneumatics costs considerably less to build and operate. This is partly because usually, air is used as the fluid, so no reservoir is needed to store fluid, nor is there a need to provide means to recover fluid. When higher force or torque is needed, pneumatics needs much larger motors or cylinders than hydraulics. So, when higher forces are needed, usually, hydraulics is used.
• Precision: Fluids vary in controllablity. Unlike liquids, gases change volume significantly when pressurized, making it hard to achieve precise position if needed. So, when precision is needed, usually, hydraulics is used.
• Safety: Gases under high pressure are explosive. So for lower forces, usually, pneumatics is used only into the range of 100 psi (7 bar), due to the hazard of a line breach. Hydraulics is used for higher forces.

Reference

Esposito, Anthony, Fluid Power with Applications, ISBN 0-13-010225-3

See also

• Using Equivalent Lengths of Valves and Fittings
• Hydraulic machinery
• London Hydraulic Power Company
• Pneumatics
• Pneumatic circuit
• Hydraulics
• Hydraulic circuit
• Pneumatic actuator

Hydraulically powered cylinders are visible on this excavator. ... The London Hydraulic Power Company was set up by an Act of Parliament in 1883 to install a network of high-pressure cast iron water mains under London. ... Table of Pneumaticks, 1728 Cyclopaedia Pneumatics, from the Greek πνευματικός (pneumatikos, coming from the wind) is the use of pressurized gases to do work in science and technology. ... A pneumatic circuit is an interconnected set of components that convert compressed gas (usually air) into mechanical work. ... Table of Hydraulics and Hydrostatics, from the 1728 Cyclopaedia. ... A hydraulic circuit is an interconnected set of components that convert pressurized liquid (usually oil) into mechanical work. ... A pneumatic actuator converts energy (in the form of compressed air, typically) into motion. ...

External links

• Information about Fluid Power is also available on the National Fluid Power Association web-site nfpa.com
• Parker Hannifin Corporation (Commercial vendor)
• Muncie Power Products(Commercial vendor/Resource Center)
• Bosch Rexroth (Commercial vendor)
• Eaton Hydraulics (Commercial vendor)
• National Fluid Power Association (Industry Organization)
• Fluid Power Brazil (Warehouse and Services)