Torsen differential

Torsen is a combination of the words torque and sensing and works similarly to a limited slip diff except that there are no springs or clutch plates that will wear out. Instead, the torsen has three sets of worm gears and spur gears that are connected at a ratio of 1:1 to one another.

The worm gears rotate against two worm wheels at a 45º angle which in turn causes friction. Just like the limited slip diff, the collective name for all these gears and wheels is also differential gears. In short: a torsen diff lock prefers it when both wheels rotate equally, and if one wheel slips on a smooth surface (and now receives more power) while the other wheel is on hard ground, the friction between the differential gears will cause the wheel on the hard ground to also get at least some engine power.

The problem with a Torsen diff is that if one wheel lifts completely off the ground, the wheel remaining on the ground will get no power – just as with an open diff. To fix this problem, you need to lightly step on the brake (or slightly raise the handbrake), which then locks the torsen diff into a spool – more on this later.

You can use a torsen differential on a front and rear axle, as well as in the middle between two drive shafts, as is the case with the Toyota Land Cruiser 200.