Hydraulics and Pneumatics Systems (Mechanical Systems Strand)

Hydraulics

A system that uses incompressible liquids (typically oil) to transmit and control power.

Pneumatics

A system that uses compressible gases (typically air) to transmit and control power.

Pressure

Force spread over an area; in fluid power, it creates actuator force.

Volumetric flow rate

The volume of fluid moving per unit time; defined as $Q = \frac{\Delta V}{\Delta t}$.

Pascal's principle

A pressure applied to an enclosed fluid is transmitted undiminished to every part of the fluid and container walls.

Force multiplication

In hydraulics, a small force applied to a small piston creates a large force at a large piston if pressure is the same.

Active area

The area of a piston exposed to fluid pressure, affecting force in hydraulics and pneumatics.

Reservoir (tank)

Stores fluid, allows air bubbles to separate, and enables heat dissipation in hydraulic systems.

Pump

Converts mechanical power into fluid power by creating flow in hydraulic systems.

Directional control valves

Valves that route flow to extend or retract cylinders in hydraulic and pneumatic systems.

Pressure relief valve

A valve that protects the system by limiting maximum pressure in hydraulic systems.

Flow control valves

Valves that regulate actuator speed by throttling flow in fluid systems.

Compressor

Converts mechanical power into pressurized air in pneumatic systems.

FRL unit

A unit in pneumatic systems consisting of a filter, regulator, and lubricator.

Viscosity

A fluid’s resistance to flow, affecting pressure losses and internal leakage in hydraulics.

Density

Mass per volume; important for calculations involving flow and pressure dynamics.

Compressibility

The measure of how much a fluid can decrease in volume under pressure.

Bulk modulus ($K$)

A measure of a fluid's resistance to compression; higher $K$ means less compressible fluid.

Work ($W$)

Energy transferred by a force acting through a distance; calculated as $W = F \cdot s$.

Power ($P$)

Rate of doing work; for fluid systems, $P = pQ$, linking pressure, flow, and energy.

Efficiency ($\eta$)

A measure of how much input energy is converted to useful output energy.

Actuators

Components that convert fluid power into mechanical motion; includes hydraulic cylinders and motors.

Check valves

Valves that allow flow in one direction only, preventing backflow in hydraulic and pneumatic systems.

Cavitation

The formation of vapor bubbles in a fluid due to low pressure, which can cause damage when they collapse.

Aeration

The presence of air in hydraulic fluid, leading to foaming and erratic actuator motion.

Leakage

Flow loss due to external or internal leaks, impacting system efficiency and safety.

Pneumatic cylinder

A device that uses compressed air to create linear motion, found in many industrial applications.