The key differences between pneumatic and hydraulic systems are:
The fluid used: Pneumatic systems use air as the fluid, while hydraulic systems use a liquid such as oil.
The transmission of power: In pneumatic systems, power is transmitted through the movement of air, while in hydraulic systems, power is transmitted through the movement of a pressurized liquid.
The types of forces involved: Pneumatic systems typically involve forces that are relatively low in magnitude but high in speed, while hydraulic systems involve forces that are high in magnitude but low in speed.
Pascal's Law states that the pressure applied to a confined fluid is transmitted undiminished in all directions and acts with equal force on equal areas. An example of a household item that applies Pascal's Law is a hydraulic jack, which uses a confined fluid (usually oil) to transmit pressure and lift heavy objects. When the handle of the jack is pressed down, the pressure of the fluid is increased and transmitted through the system, causing the lift arm to rise.
Advantages of pneumatic systems:
They are relatively simple and easy to maintain.
They are energy efficient, as air is a readily available and inexpensive fluid.
They are safe to use, as there is no risk of explosions or fires.
Disadvantages of pneumatic systems:
They are limited in their power transmission capabilities, as the forces generated by pneumatic systems are typically lower than those generated by hydraulic systems.
They are not suitable for use in high-pressure or high-temperature applications.
They are prone to leakage, as air can escape through small openings.
Examples of pneumatic systems:
Air compressors
Pneumatic tools such as hammers and drills
Automatic doors in buildings
Advantages of hydraulic systems:
They can transmit large amounts of power with relatively small amounts of force.
They are able to generate high pressures, making them suitable for use in a wide range of applications.
They are relatively simple and easy to maintain.
Disadvantages of hydraulic systems:
They require a separate power source to operate, such as an electric motor or gasoline engine.
They can be expensive to repair if they fail or leak.
They can be hazardous to use, as the fluid used (usually oil) is flammable and can cause burns or fires.
Examples of hydraulic systems:
Hydraulic lifts in automotive garages
Hydraulic jacks and presses
Hydraulic brakes in vehicles
Excavators and bulldozers