# Question Restatement **Question:** What is the correct procedure to repair an external gear pump that has been isolated due to abrasion? **Options:** A. Separate coupling, soft shoes, replace gears, lubricate shaft B. Separate, verify shaft deflection, split, then replace bearings C. Split case, replace gears, replace gaskets, then measure backlash D. Split case, separate coupling, replace shaft, then measure backlash --- # Step-by-Step Solution & Explanation ## 1. **Understanding the Problem** - **External gear pump:** A type of positive displacement pump that uses two gears to move fluid. - **Isolated due to abrasion:** The pump is taken offline because abrasive wear (likely on gears or internal surfaces) has reduced its efficiency or caused failure. **Repair Focus:** - Abrasion primarily affects gears and internal seals/gaskets. - Standard repair steps: disassemble (split case), inspect/replace worn components, reassemble, check fit/backlash. ## 2. **Analyzing Each Option** ### **Option A:** - **Separate coupling:** Disconnects the pump from the drive. - **Soft shoes:** Not a standard gear pump repair term; applies to shoe-type pumps, not gear pumps. - **Replace gears:** Correct for abrasion, but "soft shoes" is irrelevant. - **Lubricate shaft:** Not specific enough; lubrication is done during assembly, but main issue is not shaft lubrication. **Conclusion:** **Incorrect.** "Soft shoes" is not applicable to gear pumps. --- ### **Option B:** - **Separate coupling:** Correct initial step. - **Verify shaft deflection:** Important for alignment, but not directly related to abrasion repair. - **Split case:** Disassemble pump, correct. - **Replace bearings:** Bearings may not be affected by abrasion; focus should be on gears. **Conclusion:** **Incorrect.** "Verify shaft deflection" and "replace bearings" are maintenance tasks but not the main focus for abrasion. --- ### **Option C:** - **Split case:** Disassemble to access internal parts. - **Replace gears:** Directly addresses abrasion. - **Replace gaskets:** Gaskets can be damaged during disassembly or by abrasion. - **Measure backlash:** Ensures correct gear fitment after replacement (backlash is the small clearance between gears). **Conclusion:** **Correct.** This option directly addresses the abrasion problem and follows standard repair steps. --- ### **Option D:** - **Split case:** Correct. - **Separate coupling:** Usually done before splitting the case; step order is slightly off but still relevant. - **Replace shaft:** Abrasion typically affects gears, not shaft. - **Measure backlash:** Good step. **Conclusion:** **Incorrect.** Focuses on replacing the shaft, which is not the main component affected by abrasion. --- # 3. **Correct Procedure Summary** The standard repair procedure for an external gear pump affected by abrasion is: 1. **Split the case** to access internal components. 2. **Replace abraded gears** (main wear point). 3. **Replace gaskets** as needed to prevent leakage. 4. **Measure backlash** to ensure correct gear alignment and longevity. --- # 4. **Final Answer** ## **Correct Option** **C. Split case, replace gears, replace gaskets, then measure backlash** --- ## **Summary Table** | Option | Step(s) Included | Correct/Incorrect | Reasoning | |--------|---------------------------|-------------------|--------------------------------------------------------------| | A | Soft shoes, lubricate shaft| Incorrect | "Soft shoes" irrelevant; lubrication not main concern | | B | Shaft deflection, bearings | Incorrect | Not focused on abrasion repair; bearings not always affected | | C | Gears, gaskets, backlash | **Correct** | Directly addresses abrasion; follows standard procedure | | D | Replace shaft | Incorrect | Abrasion affects gears, not shaft | --- # 5. **Summary Diagram**  *Alt text: Diagram showing external gear pump components, illustrating where gears and gaskets are located for repair.* --- # 6. **Key Takeaways** - For abrasion in a gear pump, focus on **gears and gaskets**. - **Backlash** measurement is essential after gear replacement. - Understanding component function helps select appropriate repair steps.