Answer

Hydraulic Actuator

Operating Principle: Pascal's law $P=F/A$. Pressurized oil (50–300 bar) from pump → valve → cylinder/piston → linear/rotary motion. Force $F=P\cdot A$, flow $Q=A\cdot v$.

Components: Reservoir, pump, relief valve, directional control valve, cylinder, piston, filter.

Advantages

• High force/power density (tons).
• High stiffness, good for heavy loads.
• Smooth, precise with servo valve.
• Self-lubricating.

Disadvantages

• Leakage, oil contamination, fire hazard.
• Need power pack, bulky, noisy.
• Slow response vs electric, temperature sensitive.
• Maintenance high.

Applications

• Excavator, press, industrial robot heavy payload.

Final Answer

Hydraulic = Pascal $F=PA$ via oil pressure, advantages high force, disadvantages leakage and bulk.