🔍 Key Concepts

• Compare the internal parts in the illustration to those of a typical electric starter motor (armature, field windings, brushes). • Look for features that indicate a fluid-driven motor (air or hydraulic), such as vanes or ports for a working fluid. • Think about common starting systems for medium and large marine diesel engines and what energy source they usually rely on.

💭 Think About

• Do you see any coils, commutator, or brushes that would be required if this were driven directly by electricity? • Do the cylindrical rotor and housing look more like a vane-type fluid motor, and can you spot where the working fluid would enter? • Of the options given, which energy source is most commonly used to spin a separate motor that then turns the diesel’s flywheel on larger installations?

✅ Before You Answer

• Verify whether there are electrical components (windings, brushes, commutator) clearly shown in the exploded view. • Check for ports or passages in the housing that would carry a working fluid into the motor. • Confirm which option matches a vane/rotor type starter motor commonly used on large diesel engines.