Sliding electrical contacts

There are several fundamental considerations which can be used to describe the conduction in sliding contacts in electrical machines. When these are understood, most of the problems involved in these machines can be attacked with the hope of solution. This discussion will bring these together in a manner which will hopefully be useful to anyone concerned with these problems. The most important point in all brush problems is to identify the part of the system and its operation which is causing the problem so that the effort expended is properly directed.