🔍 Key Concepts

• Gravity lube oil system operation – how oil flows from the gravity tank to bearings and back • Purpose of the sight glass (bull’s eye) – what it actually shows in a gravity system • Difference between no flow, closed valves, and empty tanks indications

💭 Think About

• Ask yourself: In a gravity lube oil system, what does the sight glass normally indicate when the system is operating correctly? • If the sight glass shows nothing, does that tell you for sure what is happening in the tank, or only what is (or isn’t) happening at that specific point in the line? • Which option describes a condition that the sight glass can positively confirm, rather than something that would still require further checks somewhere else in the system?

✅ Before You Answer

• Identify what the bull’s eye is physically connected to – line, tank, or bearings. • Decide which choices would require additional verification elsewhere (tank level, valve positions) before you could be certain. • Focus on the answer that reflects what you can say with positive certainty just from observing the sight glass, without making assumptions.