I do voluntary work for a charity called Remap; we make custom aids for disabled people. I have a case that requires on a small, high torque, low speed, 12V electric motor, and a car windscreen motor seemed to be ideal. Unfortunately, after a small amount of successful use, the motor lost power. Stripping the motor revealed the cause - the carbon brushes were tangential to the commutator rather than radial, and reversing the motor wore a slightly different contact area on the brushes, thus reducing the contact area and hence the power. Clearly they were never intended to be reversed. I'm told that the older type of windscreen motors had radial brushes and could be reversed, but nobody seems to know how to identify them. Can anyone help please?
11 years ago