🔍 Key Concepts

• Electric starting motor construction – identify the solenoid, pinion gear, and flywheel ring gear in the illustration. • How the pinion gear is moved axially to mesh with the flywheel teeth before the motor delivers full torque. • Difference between a mechanical coupling (muff/friction) and an electromagnetic solenoid-operated shift device.

💭 Think About

• In the illustration, trace what physically moves the small pinion gear toward the large flywheel ring gear. Which labeled parts do that job? • Which answer choice specifically describes an electrical/solenoid device that both closes the high‑current contacts and pushes the pinion gear into engagement? • Think about where a “muff coupling” or “friction clutch” would be located in a drive train. Do you actually see those between the starter shaft and flywheel here, or do you see a lever moved by a coil and plunger?

✅ Before You Answer

• Verify which component directly causes the axial movement of the pinion gear into the flywheel ring gear. • Confirm that the device you choose both engages the gear and completes the starter circuit (a common function in modern diesel starters). • Eliminate any options that are mainly used in air starting systems or torque‑limiting couplings, not in electric starter engagement.