This book offers the complete underpinning knowledge and principles required for Level 2 N/SVQ 'Unit Replacement' aimed at basic service personnel. It uses the format of an uncompleted workbook and a Lecturer's Guide which is available separately. This edition takes the format a stage further with a workbook that is ideal for self study as well as classroom use. The authors have further updated the technology, with new drawings and a revised Welding section, as well as reflecting changes in the standards in the Worksheets.