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RE: torsens & 'torque split'

We're getting closer.

I was given this analogy that years ago.  See if it helps at all.


To understand torque shift with a locked differential, picture a
tug-of-war game.  Two people are holding on to one end of a rope
and the rope is being pulled with steady force from the other end 
(say 100 lbs. of force).  If the two people are doing an equal job of
hanging on, they each need to pull back with 50 lbs.  If one person 
starts to slip and is only pulling back with 25 lbs, the other person 
suddenly gets 75 lbs of pull.  If one person lets go, the other gets 
pulled with all 100 lbs.  So long as the second person can still 
hold on, the rope stays put (opposite of the car moving, but I hope
you get the idea).

The analogy to an open diff would be to wrap the rope around a pully,
put one person on each end of the rope, and tug with 100 lbs on the pully.

                 ______________________ person
    <-100lbs --(O______________________ person

As long as both hold on with 50 lbs of pull, they both stay put.
If one person starts to slip, the pully moves and the tugging on
the second person lets up.

At 11:21 AM 2/25/98 -0700, Lawson, Dave wrote:
>>Orin writes:
>>In summary, open diff means 50/50 torque split at the output,
>>locked diff means the split varies between 100/0 and 0/100
>>at the output.
Someone else writes
>>I believe this statement is backwards, an open diff means 100/0
>>and 0/100. And a locked diff is set at 50/50, because both outputs 
>>are now connected as a unit and they both rotate at the same speed.
> glen writes:
>>  Torque and 'torque split' are not related to the speed or relative
>> speeds of the two shafts with an open or a locked diff. The 'torque
>> split' is purely a function
>> of the relative counterforce applied to each axle and this is a
>> function of the relative
>> traction or lack of traction available at the two road/tire interfaces
>> on the axle
>> in question. Equal traction = equal torque split. Zero traction at one
>> wheel = zero
>> total torque and zero forward vehicle acceleration/motion with an open
>> diff. Zero traction 
>> at one wheel = 0/100 'torque split' with a locked diff with the 100%
>> going to the wheel 
>> with traction - exactly what you want if you want the vehicle to
>> accelerate and move.
>I thought about this last night and pretty much came to the same
>conclusion, Orins example
>of 50/50 with an open diff was based on equal 'good' traction condition
>for the wheels in question 
>and my 100/0 or 0/100 was based on a 1 wheel slip condition. And it
>stays that way, that is, 
>once that 1 wheel starts to spin it will continue to spin using 100% of
>the applied torque. 

Paul A. Hausman                <paul@lion.com>
Lion Technology Inc., Lafayette, NJ, 07848 USA