LockedAxleBearings is Connections.Pivot.AxleBearings:
    .doc: """
    Adds one lock from each connected component to the axle,
    so that it does not slide away.
    By default it chooses the left mate on the from side
    and the right mate on the to side.
    """
    from_lock is Physics3D.Interactions.LinearSpring:
        connectors: left_from_mate.connectors
        position: -from_bearings.separation * 0.5

    to_lock is Physics3D.Interactions.LinearSpring:
        connectors: right_to_mate.connectors
        position: to_bearings.separation * 0.5
