What effect does air have on hydraulic fluid?

What effect does air have on hydraulic fluid?

• A. No effect on hydraulic fluid.
• B. Causes a slight color change but no movement issues.
• C. It increases viscosity and improves performance.
• D. It causes slow or erratic actuator movement, erosion of metering or servovalves, and high fluid temperature.

Answer: (D)

Air in hydraulic fluid makes the system behave like a sponge because the air pockets are compressible. When pressure is applied, part of the energy goes into compressing the air rather than moving the fluid, so actuator movement becomes slow or erratic. Air bubbles near metering or servovalves disrupt precise flow control and can cause cavitation, leading to erosion or pitting of valve components. The additional energy required to compress and move air also shows up as increased heat in the fluid, raising its temperature. Overall, air in the hydraulic system degrades control, accelerates wear on valve parts, and increases operating temperature.

Air in hydraulic fluid makes the system behave like a sponge because the air pockets are compressible. When pressure is applied, part of the energy goes into compressing the air rather than moving the fluid, so actuator movement becomes slow or erratic. Air bubbles near metering or servovalves disrupt precise flow control and can cause cavitation, leading to erosion or pitting of valve components. The additional energy required to compress and move air also shows up as increased heat in the fluid, raising its temperature. Overall, air in the hydraulic system degrades control, accelerates wear on valve parts, and increases operating temperature.