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Piston
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A piston permits translation along the X axis of the constraint object.
It also allows rotation around the X axis of the constraint object.
It is like a combination of the freedoms of a slider with the freedoms of a hinge
(neither of which is very free alone).


Options
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Limits
   X Axis
      Enables/disables limit translation around X axis.

      Lower
         Lower limit of X axis translation.
      Upper
         Upper limit of X axis translation.
   X Angle
      Enables/disables limit rotation around X axis.

      Lower
         Lower limit of X axis rotation.
      Upper
         Upper limit of X axis rotation.