1.  Field of the Invention
The present invention relates to a system for adjustably supporting a member for movement in three dimensions.  More particularly, the present invention relates to a system for adjustably supporting a fire sprinkler head for pivoting about two orthogonal axes and movement along a third orthogonal axis. 
2.  Brief Description of the Related Art
Most municipal and county building codes require the provision of sprinkler systems in public buildings for spraying water within the interior of the building in case of a fire.  Conventionally, the sprinkler systems consist of pipes running horizontally between a load bearing ceiling or roof of a floor or building and a non-load bearing "false" ceiling extending some distance below the load bearing ceiling.  Essentially vertically extending downcomer pipes extend, at T-connections, from the horizontal water pipes at regular intervals.  The downcomers terminate in fire sprinkler heads which extend to slightly below the level of the false ceiling.  It is conventional for the sprinkler system to be installed prior to the installation of the false ceiling, after which the false ceiling is installed, with the sprinkler heads extending through small holes in the false ceiling, cut or otherwise provided for this purpose.  It is conventional to provide a decorative collar around the sprinkler head to cover the hole made in the false ceiling for the passage of the sprinkler head. 
However, due to tolerances and variations experienced in the construction of the downcomer pipes and false ceilings, it often occurs that the downcomer pipes and false ceilings do not extend precisely transverse to one another.  It also often occurs that the false ceiling is slightly higher or lower than expected.  As a result, the fire sprinkler head may extend too far from the bottom of the false ceiling, or may not extend entirely therethrough.  As a result, it may be impossible to fit the decorative collar flush against the false ceiling; instead, the decorative collar may be spaced from the bottom surface of the false ceiling or angled thereto. 
It is therefore desirable to provide some means for three dimensionally adjusting the position of the sprinkler head relative to the false ceiling.  It is also desirable that any such adjustment be accomplished from below the false ceiling and with ordinary tools.  It is also desirable that the adjustment means be simple and cheap in construction so that it can, if necessary, be assembled by a worker at the job site.