Pneumatic and Hydraulic Systems Flashcards
7 cards from real SACA practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Pneumatic and Hydraulic Systems flashcards as text
A double-acting hydraulic cylinder is not extending fully under load. Which diagnostic check should be performed first?
Answer: Check system pressure at the cylinder port against the load requirement
Verifying that system pressure at the cylinder port meets the calculated load requirement is the first diagnostic step to identify whether the issue is pressure, flow, or mechanical.
What is the primary advantage of using pneumatics over hydraulics for high-speed, light-load applications in automation?
Answer: Air is compressible, allowing faster actuator response and simpler exhaust handling
Compressed air's compressibility and the ability to exhaust directly to atmosphere make pneumatics ideal for high-cycle, fast-response, light-duty automation tasks.
In a hydraulic proportional valve system, what is hysteresis and why does it matter for closed-loop control?
Answer: The difference in output when the same input is approached from increasing versus decreasing directions, affecting positioning accuracy
Hysteresis is the output difference when a valve is approached from opposite directions, and in closed-loop systems it creates a deadband that limits positioning accuracy and must be compensated in the controller.
Which hydraulic circuit configuration is most energy-efficient for a system where multiple actuators rarely operate simultaneously?
Answer: Closed-center circuit with a pressure-compensated variable-displacement pump
A closed-center circuit with a pressure-compensated variable-displacement pump reduces flow to near-zero when actuators are idle, minimizing heat generation and energy waste.
A pneumatic cylinder fails to hold position when the directional valve is centered. What is the most likely cause?
Answer: Internal piston seal leakage allowing air to bypass from one chamber to the other
Internal piston seal leakage allows pressurized air to bypass the piston between chambers, causing the cylinder to drift from its position when the valve is in neutral.
What is the significance of the Beta ratio (β) in hydraulic filter selection?
Answer: It is the filtration ratio indicating how effectively a filter removes particles of a given size
The Beta ratio (βx) is the ratio of particles of size x upstream to those downstream, with higher values indicating better filtration efficiency for that particle size.
In SACA certification context, what does ISO 4414 govern for pneumatic systems in industrial automation?
Answer: Safety requirements for the design, installation, and maintenance of pneumatic fluid power systems
ISO 4414 establishes safety requirements and good engineering practice guidelines for the design, construction, installation, operation, and maintenance of pneumatic fluid power systems.