Hydraulic Fluid Power. Andrea Vacca

Hydraulic Fluid Power - Andrea Vacca


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since the Second World War. In particular, the Massachusetts Institute of Technology (MIT) in the United States started working on the development of hydraulic control systems since 1939. An initially small team rapidly grew larger, making contributions in hydraulic components design and hydraulic control theories and calculation methods that are still considered fundament of fluid power discipline. Published in 1959, the work by MIT faculty Blackburn, Reethof, and Shearer [2] is perhaps the greatest technical manuscript ever written on fluid power technology, and it has influenced many following books, including this one.

      Many other universities followed MIT and established research institutes expressly devoted to fluid power research. Many of these departments are still alive, shaping research on fluid power technology. A list of the most of these research centers can be found in [3].

      The authors encourage the reader interested in learning more about the main historical passages of the hydraulic fluid power technology to consult Skinner's book [4].

      Sources: Various online sources.

Schematic illustration of the hydraulic system of a jet blast deflector.

      Source: Beasley 1990.

      The discussion on fluid power symbols and standards was initiated in the United States by the Joint Industry Conference (JIC) in 1944, and the first JIC‐defined hydraulic symbols and standards were released in 1948. Soon after, the national standardization organizations took over: in 1958 the American Standards Association (ASA) released their revised version of the JIC standard. In Europe, the Comité Européen des Transmissions Oleohydrauliques et Pneumatiques (CETOP), founded in 1962, provided a series of recommendations on graphic symbols for fluid power that were received and approved by the International Organization for Standardization (ISO).

      Finally, in 1976, the first version of ISO 1219 standard Fluid Power Systems and Components: Graphic Symbols and Circuit Diagrams was released. The ISO 1219 (parts 1 and 2) is frequently revised and updated. It is nowadays considered as the universal reference for representing hydraulic circuits.

      ISO 1219 standard is the universal reference for representing hydraulic circuits. In engineering problems involving a hydraulic control system, it is always recommended to represent the system schematic using ISO symbols and following the criteria suggested by the standard.

      Source: Harry Franklin Vickers, 1989.

      The detailed description of the ISO 1219 standard is beyond the scope of this book; all rules and conventions can be found on these two ISO standards [5, 6]. However, it is still worthwhile to summarize the primary and most important aspects introduced by the standard:

       Function representation. The hydraulic circuit schematic should focus only on the functionality of both the components and system, whereas other information such as mechanical details of the parts or physical layout of the system should not be represented.

       Symbols. The standard includes precise recommendations about the symbol to be utilized to represent a specific component. The symbol itself contains relevant information necessary to understand the functionality of the component.

       Additional information. In the schematic of the system, each symbol needs to comprise information necessary to understand the operation. These include a label that uniquely identifies the component, particular function of the component, and sizing information.

      All the systems presented in this book will adhere to the ISO standard of representation. The additional information will be often omitted for the sake of generality. However, it is important to point out how this information should never be neglected when the circuit is designed for an actual application.

      The circuit also provides the additional information needed to complete the


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