In a hydraulic system, which function best describes the reservoir's role besides storing fluid?

• A. To filter contaminants
• B. To aid in air separation and cooling
• C. To generate pressure
• D. To cause flow

Answer: (B)

In a hydraulic system, the reservoir’s extra job is to give space for air to separate from the oil and to help remove heat. As oil circulates and sits in the reservoir, entrained air rises and can be vented away, which reduces the risk of cavitation at the pump and helps maintain smooth operation. The reservoir’s large surface area also allows heat from the oil to dissipate to the surrounding air, keeping temperatures in check. Filtration is handled by dedicated filters, not the reservoir itself, and generating pressure or forcing flow comes from the pump, not the reservoir. So the best description is that the reservoir aids in air separation and cooling.