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Bendix Type Starter Drive:

  • Definition: A self-engaging starter drive gear system where the gear moves into engagement with the engine’s flywheel when the starter motor starts spinning and automatically disengages when the starter stops. This mechanism is also known as an inertia drive.


  • Engagement: When the starter motor is activated, it begins to spin. The rotational motion causes the Bendix drive gear to move along the starter motor shaft into engagement with the flywheel.
  • Starting the Engine: The engaged gear transfers the starter motor’s torque to the flywheel, cranking the engine to start it.
  • Disengagement: Once the engine starts and the flywheel speed exceeds that of the starter motor, the gear is pushed back along the shaft, automatically disengaging from the flywheel.


  • Starter Motor: Provides the necessary torque to crank the engine.
  • Bendix Drive Gear: The gear that moves into engagement with the flywheel.
  • Helical Screw Mechanism: Facilitates the movement of the gear along the shaft.


  • Automatic Engagement/Disengagement: The gear engages and disengages automatically based on the starter motor’s operation, ensuring smooth and efficient engine starting.
  • Simplicity: The design is straightforward, making it cost-effective and reliable for many applications.


  • Automotive Engines: Commonly used in cars, trucks, and other vehicles with internal combustion engines.
  • Small Engines: Found in equipment like lawn mowers and motorcycles.

Alternative Names:

  • Inertia Drive: Another term for the Bendix type starter drive, highlighting its reliance on the inertia of the spinning starter motor to engage the gear.

In summary, the Bendix type starter drive (or inertia drive) is a self-engaging starter mechanism that automatically engages and disengages the starter gear with the engine’s flywheel, providing a reliable and efficient way to start internal combustion engines.

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