Q & A About Brushes Courtesy of St. Mary’s Carbon Q. The brush fits the holder, can I use it? A. Brushes are designed for a spe- cific application. Dimensions, while critical, do not determine which brush to use. You should always check to be sure you have the brush recom- mended for the application, as each component—material in the blank, spring, wire, insulation, terminal—is developed to produce optimal perfor- mance. Q. I can write with the brush—what does that mean? A. The ability to write with a brush indicates that carbon graphite is in the material but not how much. The proper way to determine brush composition is through a chemical or spectrographic analysis. The amount of carbon graph- ite used in each application has been carefully determined to enhance brush characteristics. Q. My brushes have magnetic prop- erties. I know because I used a mag- net test. Can I safely use the brushes? A. The fact that a magnet of un- known power can pick up or move a brush only indicates that iron is present in the brush. It does not indicate how much, or if it is the proper amount for the application. Iron works as a clean- ing agent and provides characteristics necessary for optimal brush perfor- mance. Q. Does the brighter brush have more copper? A. The color of a brush is deter- mined by the manufacturing process, not the copper content. The color ofa brush is primarily a cosmetic issue and not one of brush performance. It should not be used to compare vari- ous manufacturers’ product. Q. Is premature brush wear always the fault of the brush? A. The brush is only one piece of the puzzle when determining the cause of premature brush wear. It is the com- ponent that shows you there is a prob- lem with the unit. Other components in the unit such as the spring, commu- tator, rotor, slip ring, or the designs of the unit itself can all cause premature wear in brushes. Q. I want the brush to last longer. Do I want a harder brush with more copper? A. Hardness does not determine the life ofa brush. A “softer” brush might actually give you better wear. The manufacturing process determines the life of the brush, not the amount of cop- per or hardness of the material. When requesting changes in wear, the manu- facturer would need information from you, the end user, to aid in developing anew material. JANUARY, 2001 Page 1 of 1