Lionel CW80 AC damage other engines

Have 9 Lionel engines( Diesel and Locomotive) from 1937 to 1994. Recently purchased 2 Lionel CW80 ACtransformers. Member from a local train club said to use the AC on engines only if they had brushes. I believe my 681 has brushes and the others do not. Will I damage the other engines on the CW80 transformers.

Many thanks for your help

Larry