Automotive Driveline Geartrain Inertia 2

[shiitake86]

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

 

[digger200]

click on inetia, this might help

http://uk.geocities.com/mikebull2001/veryfirstpage.htm

 

[sreid]

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

 

[shiitake86]

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

Thanks.

-S

 

[sreid]

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