Mechanical Aptitude Mechanical Aptitude Hydraulics and Pneumatics 3 — Questions and Answers
Question 1: What is the function of an accumulator in a hydraulic system?
- Filter contaminants from fluid
- Store energy and dampen pressure spikes (Correct answer)
- Convert mechanical energy to hydraulic flow
- Control the direction of fluid flow
Correct answer: Store energy and dampen pressure spikes
An accumulator stores pressurized hydraulic fluid to supplement pump flow, dampen shocks, and maintain pressure during pump failure.
Question 2: If a hydraulic pump delivers 5 GPM at 1,000 PSI, what is the hydraulic horsepower?
- 2.9 HP (Correct answer)
- 5 HP
- 7.25 HP
- 10 HP
Correct answer: 2.9 HP
Hydraulic horsepower = (GPM × PSI) ÷ 1,714, so (5 × 1,000) ÷ 1,714 ≈ 2.9 HP.
Question 3: What causes cavitation in a hydraulic pump?
- Excessive back pressure at the outlet
- Insufficient fluid supply at the inlet (Correct answer)
- Too much fluid viscosity
- Overspeed of the electric motor
Correct answer: Insufficient fluid supply at the inlet
Cavitation occurs when the pump cannot draw enough fluid, causing vapor bubbles to form and collapse, damaging pump components.
Question 4: In a pneumatic circuit, what device converts compressed air energy into linear mechanical motion?
- Air motor
- Pneumatic cylinder (Correct answer)
- Solenoid valve
- Pressure regulator
Correct answer: Pneumatic cylinder
A pneumatic cylinder (also called an air cylinder) converts compressed air pressure into straight-line (linear) mechanical force and motion.
Question 5: Which type of hydraulic pump is most commonly used in high-pressure industrial applications?
- Gear pump
- Vane pump
- Piston pump (Correct answer)
- Screw pump
Correct answer: Piston pump
Piston pumps can operate at the highest pressures (up to 10,000 PSI) and are most efficient for demanding industrial applications.
Question 6: What is the purpose of a pneumatic muffler (silencer)?
- Increase exhaust air speed
- Reduce noise from exhausted compressed air (Correct answer)
- Filter incoming air
- Regulate downstream pressure
Correct answer: Reduce noise from exhausted compressed air
A pneumatic muffler attaches to exhaust ports to reduce the noise created when compressed air is vented to atmosphere.
Question 7: Hydraulic fluid viscosity that is too low will most likely cause:
- Sluggish cylinder movement
- Increased pump wear and internal leakage (Correct answer)
- Higher operating pressure
- Better heat dissipation
Correct answer: Increased pump wear and internal leakage
Fluid that is too thin (low viscosity) allows excessive internal leakage past seals and pump components, causing wear and efficiency loss.
Mechanical Aptitude Mechanical Aptitude Hydraulics and Pneumatics 3
What is the function of an accumulator in a hydraulic system?