Concentricity Alignment Tool

The Concentricity Alignment Tool (CAT) is used to concentrically align turbine diaphragms to the shaft of the turbine. (It is also known as Electronic Radial Alignment Gage or ERAG.) There are two measuring heads (SCAT – small and LCAT – large) that cover the range of most turbines including some of the smaller marine turbines. The CAT is manufactured by EDS Measurement Systems, Inc. in Rochester, New York, USA.

CAT Case Open CAT power supply
LCAT and SCAT heads
LCAT and SCAT heads w/accessories

Large (LCAT) and Small (SCAT) CAT heads with accessories attached.

To use the tool, the packing must be removed from the turbine and the packing slot cleaned of any wear deposits and the shaft must be cleaned to give accurate readings. The SCAT or LCAT sensor head is then fitted to the packing slot width by installing the proper sideplates and shims and then fitted to the annular space by selecting the proper length of spacer and hex contact screw. If the extra width of the sideplates does not allow the hex contact screws to be inserted into the lever arm, then the lever arm extenders could be attached to the lever arm.

Before taking measurements, temporarily insert the tool into the packing slot and insure that the lever arm can be zeroed using the lever arm adjusting screw. Also, insure that the lever arm has enough over travel in both directions from zero to prevent bottoming out of the lever arm and causing binding. Please see the post Using the Concentricity Alignment Tool for a basic overview of taking measurements.

CAT drawingAlso refer to the Concentricity Alignment Tool brochure.