Introduction to Hydraulics 1

What causes the viscosity of hydraulic fluids to decrease at high temperatures?

• Increase in molecular bonding

• Reduction in internal leakage

• Faster molecular movement reduces intermolecular forces

• Oil oxidation slows down

Which type of hydraulic fluid has the best fire resistance but is also the most expensive?

• HFA

• HFB

• HFC

• HFD

In a hydraulic system, what would happen if the viscosity is too low at operating temperature?

• Cavitation risk is reduced

• System response improves

• Lubrication effectiveness decreases

• Heat dissipation increases

What is the primary function of a pressure relief valve in a hydraulic system?

• Convert flow to pressure

• Maintain minimum temperature

• Limit system pressure to prevent damage

• Separate fluid and air

What happens to gas viscosity as temperature increases?

• It decreases

• It remains constant

• It increases

• It becomes zero at critical point

Which type of hydraulic pump is most suitable for high pressure and high efficiency?

• Centrifugal pump

• External gear pump

• Vane pump

• Axial piston pump

Which hydraulic fluid property prevents rust and extends system life?

• Viscosity Index

• Lubricity

• Demulsibility

• Corrosion protection

What is the correct formula for absolute pressure?

• Absolute Pressure = Atmospheric Pressure - Gauge Pressure

• Absolute Pressure = Atmospheric Pressure × Gauge Pressure

• Absolute Pressure = Gauge Pressure + Atmospheric Pressure

• Absolute Pressure = Gauge Pressure / Atmospheric Pressure

Which filter media is best for fine filtration and high dirt-holding capacity?

• Wire mesh

• Perforated plate

• Fibrous media

• Foam

What is the purpose of baffles in a hydraulic reservoir?

• Increase pressure

• Increase turbulence

• Decrease cooling time

• Separate return and suction flows, reduce turbulence