An overforce mechanism comprising a driving assembly a driven assembly and a variably engageable coupling shunts or dampens a motion of a control cylinder for a hydraulic device when that motion exceeds a predefined unsafe threshold. The overforce mechanism avoids or reduces damage either to the device itself to ancillary devices and/or to the patient. In an aspect the variably engageable coupling may include a biasing mechanism and a coupling member wherein the biasing mechanism automatically resets or releases upon reaching a force or tension threshold. Further the overforce driven assembly may include an overforce rod that allows the force or motion to be channeled away from the source. The variably engageable coupling may comprise a dowel and spring mechanism that automatically resets with tension.
