Re: open diffs at the limit.

[Orin Eman <orin@wolfenet.com>]

> no dave,  we've lost traction at [either] axle.  same scenario as scott
> proposed with the torsen....

> agree with your conclusions about the open centre diff, but you 'lose'
> an axle with the centre diff locked and you might be sending 50% of
> torque that way, but none is getting to the ground.  the torsen is
> sending (wasting) 30% of it's torque, while the generation 1 setup is
> wasting 50%.  win for the torsen.

> no dave,  we've lost traction at [either] axle.  same scenario as scott
> proposed with the torsen....


> agree with your conclusions about the open centre diff, but you 'lose'
> an axle with the centre diff locked and you might be sending 50% of
> torque that way, but none is getting to the ground.  the torsen is
> sending (wasting) 30% of it's torque, while the generation 1 setup is
> wasting 50%.  win for the torsen.

NO.  Again, locked diff can send 100% to one axle if it has the
grip.  Think about this... with a locked diff, one axle with
no grip (imagine wheel in the air), the axle with no grip
becomes no more than a useless appendage to the other shaft.
Take a pencil, one with an eraser on the end.  Grip it in
the middle.  Put the eraser end on a reasonably grippy surface.
Turn the pencil as if it is an axle and the eraser a wheel.
All the torque you apply to the center of the pencil is
obviously going to the eraser end, the other is just flapping
around in the air doing nothing.  Add some bearings, you
have to overcome the friction of the bearings, that's all.

A LOCKED DIFF CAN TRANSFER 100% OF INPUT TORQUE MINUS BEARING
FRICTION TO ONE AXLE!!!

BTW, torque, cannot be 'lost'.  If input torque to the system
as a whole exceeds output torque + plus frictional losses,
then the whole drive train accelerates at a rate proportional
to excess torque divided by the moment of inertia of the
whole system.

It is the OPEN diff that gives a 50/50 output distribution...
and it is CONTROLLED by the output with LEAST traction...
open diff, one wheel on slippy surface, only twice traction
at slippy surface transferred, excess torque accelerates
drivetrain and wheel, ie the wheel on the slippy surface
spins along with the drivetrain.  Sorry to say it, but that's
the physics of the matter.

Orin.