Here are a couple links for you to read up on further:
Eaton Posi Trac (LSD) = http://www.eatonperformance.com/differe ... i-lsd.html
From their website: "The Eaton Posi LSD prevents wheel slip before it can get started. To do that, carbon disc clutch packs, preloaded by a central spring assembly, are located behind each differential side gear. When torque input increases the clamping load on the clutch packs increases. That causes the chatter-free clutch packs to grab and transfer power to the other wheel.
Muscle cars, hot rods and mild off-road vehicles should look to Eaton's limited-slip differential for their traction answers. And the fact is, Eaton's Posi units are virtually bullet proof."
Eaton E-Locker = http://www.eatonperformance.com/differe ... ocker.html
From their website: "Designed expressly for 4-wheel drive systems to give you the ability to lock or unlock the differentials when necessary. When locked the Eaton ELocker performs as a full locker, capturing 100% of available torque and sending it equally to both ends of the axle.
The ELocker is built with precision-forged gears that are designed to mesh perfectly, providing improved strength and durability over a standard cut gear. Its ease of installation, reliability and push-button activation make ELocker an absolute must for all traction and off-road performance applications."
Detroit TrueTac (from Eaton) = http://www.eatonperformance.com/differe ... etrac.html
From their website: "Engineered to work efficiently in front and rear axles, semi-floating (C-clip axles) and transfer cases. Power transfer is so smooth, it literally goes unnoticed by the driver - even in front wheel drive axles.
Proven design, low cost and effective performance, all make the Detroit Truetrac limited slip differential the ideal choice for a wide variety of vehicle applications. No maintenance - Just Traction!"
Now: http://auto.howstuffworks.com/differential4.htm
"Clutch-type Limited Slip Differential"
The clutch-type LSD is probably the most common version of the limited slip differential.
This type of LSD has all of the same components as an open differential, but it adds a spring pack and a set of clutches. Some of these have a cone clutch that is just like the synchronizers in a manual transmission.
The spring pack pushes the side gears against the clutches, which are attached to the cage. Both side gears spin with the cage when both wheels are moving at the same speed, and the clutches aren't really needed -- the only time the clutches step in is when something happens to make one wheel spin faster than the other, as in a turn. The clutches fight this behavior, wanting both wheels to go the same speed. If one wheel wants to spin faster than the other, it must first overpower the clutch. The stiffness of the springs combined with the friction of the clutch determine how much torque it takes to overpower it.
Getting back to the situation in which one drive wheel is on the ice and the other one has good traction: With this limited slip differential, even though the wheel on the ice is not able to transmit much torque to the ground, the other wheel will still get the torque it needs to move. The torque supplied to the wheel not on the ice is equal to the amount of torque it takes to overpower the clutches. The result is that you can move forward, although still not with the full power of your car.
"Locking and Torsen®"
The locking differential is useful for serious off-road vehicles. This type of differential has the same parts as an open differential, but adds an electric, pneumatic or hydraulic mechanism to lock the two output pinions together.
This mechanism is usually activated manually by switch, and when activated, both wheels will spin at the same speed. If one wheel ends up off the ground, the other wheel won't know or care. Both wheels will continue to spin at the same speed as if nothing had changed.
The Torsen differential* is a purely mechanical device; it has no electronics, clutches or viscous fluids.
The Torsen (from Torque Sensing) works as an open differential when the amount of torque going to each wheel is equal. As soon as one wheel starts to lose traction, the difference in torque causes the gears in the Torsen differential to bind together. The design of the gears in the differential determines the torque bias ratio. For instance, if a particular Torsen differential is designed with a 5:1 bias ratio, it is capable of applying up to five times more torque to the wheel that has good traction.
These devices are often used in high-performance all-wheel-drive vehicles. Like the viscous coupling, they are often used to transfer power between the front and rear wheels. In this application, the Torsen is superior to the viscous coupling because it transfers torque to the stable wheels before the actual slipping occurs.
However, if one set of wheels loses traction completely, the Torsen differential will be unable to supply any torque to the other set of wheels. The bias ratio determines how much torque can be transferred, and five times zero is zero.
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