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Automotive Driveline Geartrain Inertia
2

Automotive Driveline Geartrain Inertia

Automotive Driveline Geartrain Inertia

(OP)
Guys, I'm having trouble calculating the inertia contained in an automotive driveline. This is a simple automotive 'live axle' design where torque is diverted from a single input (differential) to two axles.

Q1. Lets say that the inertia exiting the transmission output is 1 kg-m2, how does this change the inertial of the axle if the final drive ratio is 4.77:1?

Q2. Can I sum the inertia of the two axles together as an approximation? Can I sum the wheel inertia?

Thanks for looking, I've been having trouble figuring this out and I can't really find any resources.

-S

RE: Automotive Driveline Geartrain Inertia

Inertia is reflected by the inverse square of the gear ratio.  So your axle inertia is reflected by 1/(4.77)^2

RE: Automotive Driveline Geartrain Inertia

(OP)
Thank you for your help. Could you explain the difference in reflected inertia based on how you refer the input or output.

Thanks.

-S

RE: Automotive Driveline Geartrain Inertia

In your case, the input is the drive shaft.  The reflected inertia is everything rotating on the axle shafts.

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