Viscous coupling unit. A unit fitted as standard to all Range Rovers across the centre differential (not instead of it) automatically to effect locking of the differential when a significant speed difference between front and rear propeller shafts is sensed. Conceptually it comprises a cylinder attached to the rear prop shaft into which an extension of the front prop shaft is introduced. Discs are attached alternately to the front prop shaft and the inside of the cylinder so that they interleave very closely within the cylinder. The cylinder is sealed at both ends and is filled with a special silicone fluid which has the characteristic of markedly increasing its viscosity when stirred. Thus when one prop shaft rotates relative to the other one - the situation of front (or rear) axle wheel-spin - the fluid increases its viscosity enough to lock the shafts together. When relative rotation ceases the viscosity changes back to its original value and the shafts are unlocked. The viscous coupling unit (VCU) has the advantage of being automatic on both engagement and disengagement and its action is gradual and without shock-loading to the transmission.

Versalar Configuration Utility. A Web-based, menu-driven, graphical user interface that configures and manages Bay Networks Versalar 5399 and 8000 Remote Access Concentrators (RACs). See also RAC TM, Versalar TM.

Virginia Commonwealth University