To Lock Rigid Bodies
Use this command to keep one or more follower bodies stationary with respect to a lead body during a specific time period in the animation.
1. Click 
Lock Rigid Bodies. The Lock Rigid Bodies dialog box opens. Enter a new name or accept the default name, BodyLock#, where # represents an incremental number that increases as events are added.
Lock Rigid Bodies. The Lock Rigid Bodies dialog box opens. Enter a new name or accept the default name, BodyLock#, where # represents an incremental number that increases as events are added.2. Middle-click to define the ground body as lead, or select another rigid body.
3. Select the follower bodies. Follower bodies are outlined in red.
4. Enter values for the Start Time and the End Time in the Value boxes.
5. Select reference events for each value from the After list.
6. Click Apply. The locking event is added to the timeline.