In a POS (gov loc) differential... It operates as follows:
clutch packs are engaged all the time just like a limited slip, except weaked than most other limited slips. When the speed of one wheel exceeds the speed of the other by a set (way too many) number of RPMs, the stupid little weights and widgits and such cause it to lock up solid...like a spool. When the load comes off it, it goes back to limited slip operation. It should have additive in it....well actually, if you take my not so humble opinion, it should have a detroit in it.