🔍 Key Concepts

• Hydraulic reservoir breathing and why reservoirs need to be vented to atmosphere • What happens to pressure inside a closed tank when fluid leaves or returns if air cannot freely enter/exit • Difference between over‑pressure and partial vacuum in a closed container

💭 Think About

• When hydraulic fluid is pumped out of the reservoir into the system, what happens to the volume inside the tank if no air can enter through the breather? • When fluid returns to the reservoir, what happens to the air space if no air can escape through the breather? Does this tend to create pressure or suction? • Which of the listed effects would most directly result from blocked air flow through the breather element itself, rather than from problems in the hydraulic lines or actuators?

✅ Before You Answer

• Focus on how a fouled (blocked) breather affects the air space above the oil in the reservoir, not the oil flow in the lines • Ask whether the reservoir level change would more likely cause internal pressure build‑up or a vacuum if it cannot breathe • Eliminate choices that talk about changes in line flow or actuator speed, and concentrate on the effect on the reservoir pressure condition