The first two editions of this book, edited by Dr.-Ing. W. Fahrenbach, were published in 1939 and 1949. In the meantime, electronic control has been widely introduced in resistance welding machines, which has proven particularly effective here. As a result, the material has expanded to such an extent that the publisher has decided to release this book as a double issue. The new areas of content have been worked on by Dipl.-Ing. W. Brunst, who has also taken on the task of merging this new section with the content of the last edition, newly revised by Dr. Fahrenbach, into a cohesive whole. Thus, this workshop book now appears in a completely new format with double the volume and entirely revised content. It aims to serve the practice of resistance welding and to assist not only the operator but also the designer and the student. On this occasion, we would also like to thank all the companies that generously provided the materials and images used, especially Robert Bosch GmbH, which enabled the publication of the book in this form through their consent. The authors express their gratitude to Mr. Ing. K. Bauer for reviewing the corrections and particularly for the review and revision of the control engineering section.