Question 43 1AE01 - First Assistant Engineer

The Correct Answer is C **Explanation of why option C is correct:** A gravity feed lubricating oil system relies entirely on gravitational force to move the oil from the storage/supply tank (the gravity tank) to the components requiring lubrication (the points of lubrication, such as bearings). 1. **The Lube Oil Gravity Tank:** For gravity to cause the oil to flow downward to the points of lubrication, the gravity tank **must** be positioned vertically **above** the components it is feeding. This establishes the necessary pressure head (hydrostatic pressure) to ensure flow. 2. **The Lube Oil Reservoir/Sump:** After the oil passes through the bearings, it must be collected so it can be filtered, cooled, and eventually returned to the gravity tank for reuse. This collection point (the reservoir or sump) is typically placed at the lowest practical point in the system, which is **below** the points of lubrication, allowing gravity to drain the used oil into it. Pumps are then used to transfer the oil back up to the high-level gravity tank, completing the cycle. Therefore, Option C accurately describes the essential vertical arrangement for a functional gravity feed system. **Explanation of why the other options are incorrect:** * **A) The lube oil gravity tank and the lube oil reservoir/sump are both above the points of lubrication.** * While the gravity tank must be above the lubrication points, the reservoir/sump must be *below* them to effectively collect the drained oil via gravity. If the sump were above the lubrication points, the used oil would not naturally drain into it. * **B) The lube oil gravity tank is below the points of lubrication and the lube oil reservoir/sump is above the points of lubrication.** * This arrangement fundamentally defeats the purpose of a *gravity* feed system. If the gravity tank is below the points of lubrication, gravity cannot feed the oil to the bearings. Furthermore, having the sump above the bearings would prevent oil from draining into it. * **D) The lube oil gravity tank and the lube oil reservoir/sump are both below the points of lubrication.** * If both tanks are below the lubrication points, the oil cannot flow from the gravity tank to the bearings using gravity, nor can the used oil drain by gravity into the reservoir/sump (as it would have to flow uphill to get there).