2009-2010 Polaris RZR Factory Service Manual, Page 266Get this manual
FINAL DRIVE REAR GEARCASE (RZR INT'L)
General Operation
The RZR (INT'L) rear gearcase has three traction operational modes: AWD, Differential Lock, and Differential UnlockLocking the rear differential is beneficial in low traction and rough terrain conditionsUnlocking the rear differential makes maneuvering easier and minimizes damage to turf and sensitive terrains