Use a Distance Joint for 2D and 3D components to maintain a specified distance between two components. The two components behave as if they are connected through a rigid massless link with ball joints at the ends. No additional degrees of freedom are added by this joint.

Select a Source. Select any Attachment, Rigid Domain, Spur Gear, Helical Gear, Bevel Gear, Worm Gear, Spur Rack, Helical Rack, or Base Motion that is defined for the model. The option Fixed is also available. When Fixed is selected, the source side of the joint is fixed in space, and not connected to any modeled parts. Selecting a base motion gives a behavior similar to using Fixed, with the exception that the base now can have a nonzero prescribed displacement, velocity or acceleration.

Select a Connection point — Centroid of source, Centroid of selected entities, or User defined.

The connection point is the exact location where the fictitious ball joint is connected to the source attachment. If the source is Fixed, the only option available is User defined.

Select a Destination. Select any Attachment, Rigid Domain, Spur Gear, Helical Gear, Bevel Gear, Worm Gear, Spur Rack, or Helical Rack that is defined for the model. Select a Connection point — Centroid of destination, Centroid of selected entities, or User defined.

In large models, the list of available attachments can become long. You can then create geometric filters to narrow down the search. When the Use selection filter check box is selected, two subnodes named Source Filter and Destination Filter are added to the joint node. In these subnodes you can make graphic selections of the objects whose attachments should be shown in the Source and a Destination lists.

Enter an Extension Δ. The default is 0, in which case the distance is equal to the initial geometrical distance between the two connection points.

Physics tab with Multibody Dynamics selected:
Global>More Joints>Distance Joint