🔍 Key Concepts

• Function of an air starting motor on a diesel engine • How overrunning clutches work to prevent mechanical over‑speed or back‑driving • Difference between control/interlock devices and actual over‑speed protection

💭 Think About

• Think about which device physically disconnects or protects the motor itself when the driven equipment speeds up beyond the motor speed. • Ask yourself: which options are mainly for starting control and sequencing, and which one directly prevents damage from over‑speeding? • Consider what happens to the air starting motor once the diesel engine has started and comes up to speed—what prevents the motor from being driven too fast by the engine?

✅ Before You Answer

• Identify which choice is a mechanical device that automatically disengages when the driven shaft turns faster than the driving shaft. • Separate control/interlock functions (electrical or pneumatic control) from mechanical over‑speed protection. • Verify which component is standard in many starter drives (including automotive starters) to prevent the starter from being driven by the running engine.