WTMA Hydraulics and Fluid Dynamics 3 — Questions and Answers
Question 1: A hydraulic cylinder has a bore of 3 inches and operates at 1,000 psi. Approximately what push force can it generate? (Force = Pressure × Area)
- 7,069 lbs (Correct answer)
- 3,000 lbs
- 9,425 lbs
- 1,000 lbs
Correct answer: 7,069 lbs
Area = π × (1.5)² ≈ 7.07 sq in; Force = 1,000 × 7.07 ≈ 7,069 lbs.
Question 2: Which type of pump is most commonly used in hydraulic systems to move fluid?
- Positive displacement pump (Correct answer)
- Centrifugal pump
- Jet pump
- Submersible pump
Correct answer: Positive displacement pump
Positive displacement pumps deliver a fixed volume per cycle, making them ideal for high-pressure hydraulic systems.
Question 3: If a hydraulic fluid reservoir runs low, what is the most likely immediate consequence?
- Pump cavitation and potential pump damage (Correct answer)
- Increased system pressure
- Faster cylinder movement
- Improved filtration
Correct answer: Pump cavitation and potential pump damage
Low fluid causes the pump to draw in air, leading to cavitation which damages pump components.
Question 4: A directional control valve in a hydraulic system is used to:
- Control which way a cylinder extends or retracts (Correct answer)
- Regulate system pressure
- Filter fluid contaminants
- Measure flow rate
Correct answer: Control which way a cylinder extends or retracts
Directional control valves route fluid to one side of a cylinder or the other to control direction of motion.
Question 5: Hydraulic fluid must be incompressible for the system to work properly. Why?
- So force is transmitted instantly without energy loss to compression (Correct answer)
- So the fluid stays cool under pressure
- So the fluid can lubricate moving parts
- So the fluid does not mix with air
Correct answer: So force is transmitted instantly without energy loss to compression
Incompressible fluid transmits force directly; a compressible fluid would absorb energy before moving the load.
Question 6: What is the purpose of a hydraulic accumulator?
- Store pressurized fluid to supplement pump flow on demand (Correct answer)
- Filter particles from the fluid
- Cool the hydraulic fluid
- Measure system pressure
Correct answer: Store pressurized fluid to supplement pump flow on demand
An accumulator stores energy as pressurized fluid and releases it when demand exceeds the pump's output.
Question 7: In a hydraulic system, increasing the length of a hose between the pump and cylinder will:
- Increase pressure drop due to friction losses (Correct answer)
- Increase flow velocity
- Decrease system pressure at the pump
- Have no effect on system performance
Correct answer: Increase pressure drop due to friction losses
Longer hoses create more friction, which increases pressure drop and reduces pressure available at the actuator.
WTMA Hydraulics and Fluid Dynamics 3
A hydraulic cylinder has a bore of 3 inches and operates at 1,000 psi.
Approximately what push force can it generate? (Force = Pressure × Area)