Foreword to the online edition of the O+P-Fachlexikon "Fluidtechnik von A bis Z" (O+P technical glossary "Fluid technology from A to Z")

Hydraulic and pneumatic drive and control technology – collectively termed fluid technology – is a comparatively young specialist area of drive and automation technology that only started to become used widely in industry in the middle of the 20th century. Prior to that it was mostly in special applications where the benefits of fluid technology were used, for instance in pneumatic brakes for railway rolling stock or hydraulic steering power assistance systems for cars, on presses or in servo hydraulic follow up controls for aircraft systems.

In the 1950s fluid technology started to be used increasingly in machine and plant engineering, in mobile machinery, in motor vehicles, in shipping as well as in aerospace. It was used to automate work processes, to simplify machine designs and to increase performance. Even though fluid technology was of varied application and was an important specialist area for machine engineering, up to this point it was not a subject at colleges and universities – unlike electrical engineering. As a consequence up until the 1970s hydraulic components and systems were primarily developed by innovative engineers based on customer requirements and practical experience. Countless devices, parts for devices and technical methods came about and had to be given names so manufacturers and users could understand each other. Many manufacturers undertook this task largely at their own discretion, especially as by means of clever neologisms they were able to differentiate themselves from competitors. This situation marked the terminology in fluid technology for a long time.

With the O+P-Fachlexikon "Fluidtechnik von A bis Z" (O+P technical glossary "Fluid technology from A to Z"), the 1st edition of which was published in 1989 by Vereinigte Fachverlage in Mainz, Hans Ebertshäuser made an important contribution to defining and explaining the terms and names used in fluid technology. The lexicon triggered some productive discussion about terms and their technical context in the fluid technology sector and among users. University research and standardisation have also contributed to the harmonisation and refinement of terms and definitions. For this reason in 1995 there was a 2nd revised edition with the joint authorship of Hans Ebertshäuser (who died in 1992) and Siegfried Helduser. Here in particular terms from the areas of measurement and control, microelectronics as well as electrohydraulic control technology were revised or added.

20 years after the publication of the 2nd edition, a renewed revision of the O+P technical glossary of fluid technology is necessary: Mechatronics, digital signal processing and new safety standards make the addition of numerous additional terms and definitions necessary to reflect the current state-of-the-art. From January 2015 this task was taken on by a team of authors at HAWE Hydraulik SE, Munich to provide a helpful reference work for fluid technology. The new edition will no longer be published as a printed book, but as an online version in German and English on the homepage of HAWE Hydraulik SE.

Univ.-Prof. Dr.-Ing. Siegfried Helduser, Faculty of Mechanical Science and Engineering, TU Dresden

Dr. Michael Werner, Vereinigte Fachverlage GmbH, Mainz