Definitions to Start the Course

All machines require some type of power source and a way of transmitting it to the point of operation. The three methods of transmitting power are mechanical, electrical, and fluid. Fluid power deals with the transmission and control of energy by means of a pressurized fluid. Although it is common to think of a fluid as simply a liquid, a fluid is actually considered to be a gas or a liquid. Hence, there are two primary branches of fluid power:

- Hydraulics - uses a liquid, usually oil
- Pneumatics - uses a gas, usually air

Pneumatics

Pneumatics is used in most, if not all, industries. Manufacturing and transportation rely heavily on pneumatic technology. Pneumatics has many of the same advantages as hydraulic systems. Its actuators can be stopped without hurting them, actuator motion can be linear or rotary, and speed is easy to control. Pneumatics has some advantages over hydraulics as well. These include:

- High Speed - Very high speeds can be obtained with pneumatics.
- Not Messy - Pneumatic systems don't leak oil, so they are better suited to applications such as textiles or electronics.
- Low Cost - Pneumatic system components are lower in cost than hydraulic components, because they are designed for operation at much lower pressures.

Pneumatics, however, is not without its disadvantages. Pneumatic systems usually don't operate above 150 psi. This means that they are suited only for lower force applications. Also, the compressibility of the gas causes pneumatic actuator motion to not be as smooth as hydraulics.

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