Limited slips are reactive. They limit over-speeding of the inner wheel
by coupling it to the outer, more heavily loaded wheel. In contrast,
"torque biasing" differentials are proactive. They send increased torque
to the tire that is more heavily loaded prior to wheel spin. Two makes
are in use in race cars, the Gleason-Torsen and the Quaife. Gleason made
a few diffs for race cars in the '80s but are no longer producing them
except for some Japanese street car manufacturers. The Quaife is
virtually identical in operation and is still being produced.
Torque biasing operation is based on the fact that worm gears transmit
torque efficiently only in one direction. In practice, side gears are
coupled to each axle and mate with several pair of overlapping planetary
worm gears. These worm gears float in the housing and when power is
applied, the gears are pushed outward, causing friction between their
tips and the recesses inside the case, thus resisting rotation. This
allows more torque to be biased toward the wheel with more traction.
While they have the advantage of being proactive. torque biasing
differentials are not without faults. First, they are quite heavy and
have a lot of mass concentrated just inside the case, giving them quite
a bit of rotational inertia. Second, a fair amount of power is turned
into heat due to the friction of all the gears inside the case, and they
never fully lock. Finally, they send more torque to the more heavily
laden outside wheel which, opposite to the effect of the Detroit Locker,
gives the car a power-on over-steering tendency
My $0.02 and worth every penny
Fred Crowley - Team Healey Texas
N5572B@aol.com wrote:
>In a message dated 5/9/05 4:50:44 P.M. Pacific Daylight Time,
>msalter@precisionsportscar.com writes:
>
>As I understand it the problem with the Quaffe unit is that if you
>completely loose traction on one wheel that wheel just spins like an open
>diff.
>
>
>
>
>I have not heard this about the Quaife, quite the opposite...but they do
>operate similar to an open diff in deceleration which can be a good thing in
>low
>traction situations. No interest, just sharing the knowledge...if it can be
>called that.
>Dave Duffey
>Paradise, CA
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