Machinery Repairman Practice Test

Pumps driven by electric motors aboard gas turbine ships are gear pumps. Gear pumps are a type of positive-displacement pump that use meshing gears to trap a fixed volume of liquid and move it from suction to discharge. This design delivers a steady, predictable flow at a given speed, which is ideal for transferring a variety of liquids such as fuel oil, lubricants, and hydraulic fluids used on ship systems. The rugged, compact construction and good handling of viscous liquids make gear pumps a reliable choice for marine service where electrical power is readily available and precise flow control matters. Other pump types are either more suited to different service conditions or don’t provide the same combination of constant flow and ability to handle a range of liquids when driven by an electric motor. For example, centrifugal pumps rely on pressure differences and can have flow that varies with system pressure, which isn’t as stable for some shipboard fluid transfer tasks. Diaphragm pumps are useful in specific dosing or chemical applications but aren’t the standard choice for the broad, everyday liquid transfer duties on gas turbine ships. gear pumps strike a practical balance of reliability, efficiency, and versatility for this environment.