An interlock mechanism is provided which includes a controllable fluid within a hydraulic link. The controllable fluid, preferably comprising a magnetorheological fluid, is disposed within the interlock mechanism. The viscosity of the fluid can be changed to allow the interlock mechanism to be actuated....http://www.google.de/patents/US6308813?utm_source=gb-gplus-sharePatent US6308813 - Fluid controlled interlock mechanism and method
