So the hummer, for all its badass off road cred, didn’t actually come as standard (at least originally) with locking differentials. The military was concerned about the misuse of the locker and asked instead for a new type of limited slip call the torsen. Its a mechanical TORque SENsing type unit that doesn’t rely on a slipping wheel to bias torque. They specd a unit with a VERY high torque bias ratio of 4:1 and since the gears were reduced at the hub to the tune of 1.92 to one that mean that applying a small amount of brake torque to all wheels would bias a large amount of torque across the diff. Think of it like this, if you put 100 lbs of braking torque to all wheels the torsen would take that 100 and multiply it by 4 x 1.92 to get 768 lbs feet additional torque to the good wheel. So if you applied 200 lbs feet engine torque, the good wheel would get 33.3 x that for 6660, PLUS the 768 from the braked wheel, minus only 100 lbs-ft because the good wheel is also being braked. meaning a wheel in the air is getting 100 lbs-ft while the wheel on the ground is getting 7328 lbs feet. PLENTY to move it. Apply more brake, bias more torque to the tune of nearly 8 times the rate of the brake loss. Its a neat little trick that allows the HMMWV a lot of traction without having to do anything more complicated than ride the brakes a little. Stronger too. The clip above shows this in action, the red truck for sure is using it, The green truck too.
Its worth nothing as well that one of the trucks rear diff exploded early on the trail, the spider gears broke. It was equipped with the option e-locker and not the Torsen.