🔍 Key Concepts

• Direct-reversing diesel engines and what happens to attached pumps when engine rotation changes • How a straight impeller vane behaves when rotated in either direction • Effect of a concentric housing vs an eccentric/volute housing on pump flow characteristics

💭 Think About

• When a diesel engine reverses, what happens to the direction of rotation of the pump shaft and the impeller? How would that affect pump output if the internal design favored one direction? • Compare a concentric housing to a volute (spiral) housing: which one is designed to turn velocity into pressure more efficiently in a preferred direction, and which one is more symmetrical? • Which answer choices deal with flow symmetry in both directions, and which are about other unrelated pump problems like clogging or cavitation?

✅ Before You Answer

• Make sure you understand that direct-reversing engines change shaft rotation direction and how that affects a pump designed for one-way vs two-way rotation. • Check which choice addresses performance in both ahead and astern, and which talk about problems (clogging, cavitation) that concentric housings are not primarily meant to solve. • Verify which housing shape (concentric vs volute) is associated with directional efficiency rather than cleanliness or anti-cavitation design.