Re: Physics is...

[Dave Eaton <dave.eaton@minedu.govt.nz>]

>------------------------------
>
>Date: Tue, 10 Mar 1998 10:42:44 -0800 (PST)
>From: Orin Eman <orin@wolfenet.com>
>
>> >Given this, I think we can remove any quantitative treatment of
>> >speed differential and say if there is any speed differential,
>> >max torque is going to the slower turning shaft.
>
>> The torsen is not a binary switch. The amount of torque shift 
>> depends upon how much the two driveshafts resist turning, and 
>> the difference between the two.
>
>Quite true, it is not a binary switch, what you say is absolutely
>correct _if the shafts are turning at the same speed_.
>
>I said 'if there is any speed differential'... for there
>to be a speed differential, all the friction surfaces must in
>the torsen must be slipping, therefore all frictional forces must
>be at their maximums, therefore torque split is at the maximum.
>

no orin, this is not what the torsen paper describes the torsen as doing
(despite the 'weasel words' in section 5.2).  reference the figure on page 3
and this show a *linear* relationship between speed differential and torque
transmitted.

a viscous diff does not exhibit a linear relationship, rather an exponential
one, simply due to it's use of driveshaft rotational speed to determine torque
shift.  the torsen does not, of course, do this.

>If then max torque split is more than one shaft can take, it spins of course
>and speeds up to the speed of the faster axle.  Once it reaches that
>speed, then torque will probably go to the other axle.
>

no again, rotational speed has nothing to do with it, rather the torque
reaction of each axle to the torque being distributed.  on decreasig torque
reaction, torque is transmitted to the other axle, governed by the bias ratio,
until both axles exceed their torque reaction limits...


>I believe that a consequence of 
>> shifting torque is that the driveshaft with less traction is forced 
>> to spin faster than the other. Scott says that it works the other 
>> way -- that the torsen "reads" the driveshaft speeds to determine 
>> torque split.
>
dave
'95 rs2
'90 ur-q