🔍 Key Concepts

• Gravity type lube oil service system operation (how supply and return/overflow work) • Difference between flow to bearings and overflow back to tank • What the return drop line sight glass actually indicates

💭 Think About

• If the system is operating normally, what should you expect to see in the return sight glass while underway? • Does the sight glass tell you about oil level in the gravity tank, pump operation, or overflow condition? Which one directly relates to that location? • Could oil still be reaching the bearings even if nothing appears in the return sight glass? Think through the flow path.

✅ Before You Answer

• Trace the path: pump discharge → gravity tank → bearings → overflow/return line → sight glass • Decide what condition must exist for overflow from the gravity tank to occur during normal operation • Ask: Does the absence of visible oil in the return drop line sight glass prove anything about pump failure or empty tanks, or only about overflow behavior?