by chad3006 » Wed Feb 15, 2017 2:58 pm
If I understand your question properly, looks like those attributes define the "type" of differential the car is using.
For example:
From the factory, most cars come with a “Free” type differential. This means that power is only delivered to one of the two wheels attached to the differential. When a car is cornering the wheels on the outside have to spin at a faster speed than the wheels on the inside of the curve. “Free” type differentials allow this to happen easily, in fact if you've ever jacked up a car with the engine is running and in gear (which I don't recommend because it is not very safe) only one of the wheels will spin, the other is “free.” So that's what “free” means in differentials.
A “limited slip” differential allows both wheels to have power delivered to them, but in a limited way. It allows for a certain amount of slip, so the wheels can spin independently when needed. This is not usually available from the factory in normal passenger cars, but is usually available only on sports car models, or trucks.
A “spool,” or “locked” differential means that both wheels attached to the differential spin together and are “locked” together. No slippage can occur. This would usually only be something used on a dedicated race car. It's very popular with drag racing cars that travel in a straight line where no slippage is needed. Most racing tires are softer than standard highway tires, so the slippage is transferred to the tire itself in these cases. The tire “scuffs” in cornering.
In some modern cars there is a thing called "traction control." This allows for power to be delivered to whichever wheel needs it, allowing for traction to be optimized at all times. You'll see it a lot on all wheel drive cars.