Rear Axle interlock?

A box of kitty litter will solve an occasional "flat ground stuck" a lot cheaper than lockers.

Lockers really excell when climbing in snow and ice. Not so much when descending .

 

The diff lock doesn't engage the rear axle - both drive axles in a 6x4 twin screw truck are always live. It locks the outputs so that they always rotate at matching speeds. In normal operation, when unlocked, power is supplied to both axles, but being unlocked allows it to compensate for differences in tire height across each axle (e.g., you just put new tires at 28/32nds in the #3 axle, but the ones on the #2 axle are at 20/32nds.... driving like this on hardball roads with the power divider locked would tear up your tires quick). Now, if one axle shaft starts spinning freely while the power divider's unlocked, all the torque goes with it, which is where the lock comes in.
I've never driven a highway truck with full lockers, but the one I drive on the side has a rear locker, and it's a good setup for a highway truck. I wouldn't use it in severe off roading work, but it's gotten me out of sticky spots in snow and muddy lots where other truck have gotten stuck.

 

So it means in case a person wants to buy a tractor we can spot a soon to break diferential by just looking if tires on either two diferentials are worn out even when the tractor looks 100 % perfect? I need some help here.