Starter motor drive — method of transmitting torque to the engine flywheel In a typical automotive starting system, the starter motor turns the engine via which type of drive engagement?

Introduction / Context:
Cranking the engine requires a compact, high-torque transmission from the electric starter motor to the flywheel ring gear. The drive must engage only during starting and disengage afterward to prevent overspeeding the starter.

Given Data / Assumptions:

• Conventional 12 V starter with a pinion (Bendix or solenoid-shift mechanism).
• Flywheel has a hardened ring gear.
• Engagement is temporary during cranking.

Concept / Approach:
The starter uses a small pinion gear that meshes with the large ring gear on the flywheel. This gear drive provides a large speed reduction and torque multiplication needed to overcome engine compression and friction at low cranking speeds.

Step-by-Step Solution:
Starter solenoid actuates → pinion moves to mesh with ring gear.Motor energizes → torque transmitted through gear mesh.Engine starts → pinion retracts or overruns via a one-way clutch.

Verification / Alternative check:
Service diagrams show the pinion-to-ring gear mesh as the standard mechanism; no belts or chains are used.

Why Other Options Are Wrong:
Belts and chains are unsuitable for brief, high-torque intermittent engagement and would require tensioning mechanisms.

Friction rollers would slip and wear quickly under cranking loads.

Common Pitfalls:
Worn ring gear teeth or misadjusted pinion throw cause grinding; weak batteries or bad solenoids hinder engagement.

Final Answer:
gear drive