Why can't you specify viscous coefficients on the carrier side in Differential block

Hello, I am wondering why you can not specify viscous friction coefficient at the carrier side of the differential?

Looking at the source code of the block, all it would take is to alter it on the line 122.

mu_visc=mu_visc(2:3) instead of mu_visc=[mu_visc(2) 0]

Is there a reason for this?

On a basic differential there are bearings holding the carrier in the casing, losses of which you can not specify in this version of the block.

Answer 1

[Steve Miller]

Hi David,

The viscous friction you specify for driveshaft-casing encompasses both the bearing friction for driveshaft-casing and carrier-casing.

In the animation below (created in Simscape Multibody, example in Multibody Parts Library), the bearing friction you wish to specify varies with the rotational speed of the gray gear (carrier). The rotational speed of the carrier varies linearly with the rotational speed of the driveshaft (blue gear). Because these two speeds are linked by the speed constraint, the viscous friction coefficient "driveshaft-casing viscous friction coefficient" on the Viscous Losses tab is used to capture the viscous losses of both of these bearings.