Redundant Mates
For Motion Analysis studies, having redundant mates is the equivalent
of over-defining a SolidWorks model.
For example, consider a door with two hinges. Only one mate can restrict
the vertical translation of the door. The other is redundant. You can
consider that there is no vertical direction force component on the second
hinge. You can see this when you plot the forces.
Before running a study, remove all redundant mates. You can remove all
redundant mates manually, or have SolidWorks Motion attempt to remove
them automatically.
Automatic redundant constraint
handling can yield erroneous results. It is best to define the model such
that there are no redundant mates.
To manually remove redundant mates, try one or more
of the following, in order:
Redefine the model such that there are no redundant
mates, or as few as possible.
Identify all the redundant (over-constraining)
mates and manually change those mates into bushings on the Analysis
tab in the Mate PropertyManager.
Select Replace
redundant mates with bushings in the Motion
Study Properties PropertyManager. This option significantly slows
down the simulation time, so try this only after exhausting other options.
To specify automatic redundant mate handling in SolidWorks
Motion:
Click Motion
Study Properties 
(MotionManager toolbar).
Select Replace
redundant mates with bushings.
This option replaces any mate that has a redundant
component with a bushing. The loads in the system are distributed based
on which mates are replaced.
Related Topics
Redundant
Mate Force Constraints