Differentials — planetary gear type construction Which statement best describes the gear meshing in a planetary-gear-type automotive differential?

Introduction / Context:
Automotive differentials allow the left and right wheels to rotate at different speeds while transmitting torque from the propeller shaft. A planetary-type differential replaces bevel gears with spur or planetary elements but preserves the same kinematic function. Understanding which gears mesh clarifies how torque splits and how speed differences are accommodated.

Given Data / Assumptions:

• Planetary (spur) differential architecture rather than bevel gear type.
• Two side (central) gears connected to the left and right axle shafts.
• Multiple planet pinions carried by a cage or carrier driven by the ring gear.

Concept / Approach:
In this layout, planet pinions are in mesh with both side gears. When vehicle travels straight, the planet set does not spin about its own axes relative to the carrier and both axles rotate together. During a turn, the planet pinions rotate and walk around, allowing speed difference between side gears while maintaining torque flow.

Step-by-Step Solution:
Identify components: carrier (driven), side gears (to axles), multiple planet pinions.Determine meshing: each planet engages both side gears simultaneously.Infer behavior: equal and opposite speed deviations of side gears around the carrier speed allow differential action.

Verification / Alternative check:
Cutaway diagrams of planetary differentials show spur planets between two coaxial side gears with continuous mesh on both sides.

Why Other Options Are Wrong:
Option a specifies an arbitrary count and implies only internal gears; not essential and misleading. Option b incorrectly connects an axle to the planet carrier rather than to a side gear. Option d incorrectly fixes an internal gear to a planet; planets rotate and revolve relative to the carrier.

Common Pitfalls:
Confusing bevel gear differentials with planetary layouts; mixing up carrier drive with axle connections; assuming a single planet rather than multiple small pinions to share load.

Final Answer:
Each planetary pinion gear meshes with both the central (side) gear and the opposing internal gear to transmit differential action.