Hydraulic Fluid Power (in Italian Oleodinamica) is the discipline that deals with systems where the power is transferred through a liquid working fluid, typically oil. Fields of applications are off-road vehicles (earthmoving machines, construction machines, forklifts trucks, agricultural machines, mining machines, airport vehicles), on-road vehicles (rubbish lorries, snow removal machines, mobile cranes, ladder trucks, car transporters, street sweepers), automotive systems (steering unit, active suspensions, automatic gear shift actuation, variable valve actuation, electro-hydraulic braking systems), industrial machines (machine tools, hydraulic presses, injection moulding, packaging machines, material handling, test benches), aeronautics (primary flight controls, landing gear, rudder), naval systems (variable-pitch propellers, winches) and much more. Italy is the world’s fifth largest producer and exporter of fluid power components and systems and there is a strong demand for engineers with fluid power expertise. The Politecnico di Torino is one of the few universities in Italy delivering specific courses in Fluid Power starting from 1979. Despite the increasingly massive use of electric machines, fluid power components, due to their high power density, still remain the only viable solution in many fields. Furthermore, during this period marked by a strong focus on decarbonization and hybridization, flow power is witnessing a renewed surge towards optimizing components and systems and their integration with electric machines. The design, development, testing and production of fluid power components or systems require very specific skills, but the prerequisite is a strong and solid knowledge of the basic principles governing the generation and control of hydraulic power and the mutual interaction between components. In this context, the course presents and examines fluid power components and basic systems used in mobile and industrial applications in terms of their layout, specific features, construction and operation. Non-ideal components and their performance are introduced. Positive displacement machines and valves, in diversified architectures, are examined in terms of efficiencies and steady-state characteristics. The course then focuses on hydraulic supply systems and different ways for controlling linear actuators and hydraulic motors (for vehicle traction and lifting systems). Finally, the typical architectures used in multi-actuator mobile circuits (excavators, cranes, and so on) are presented. Students learn how to interpret fluid power schemes, to understand the function of each component in a fluid power circuit and to quantitatively evaluate the main quantities involved. Theoretical considerations are strengthened by applications grounded on a simulation approach and experimental activities. Many examples of real components are presented in the course for showing the practical implementation of the theoretical principles. Overall, aim of the course is to acquaint students with methods for the analysis and critical evaluation of fluid power components and systems.

The knowledge acquired by the students upon completion of this course involves: - to know the fundamental equations for the evaluation of the main hydraulic quantities in steady-state conditions, - to identify and quantify the sources of power dissipation in a fluid power component/system and to evaluate the efficiency, - to explain the difference between the ideal and real behaviour of a fluid power component, - to understand the rules for the construction of a fluid power scheme according to the ISO standard 1219, - to know the general methodology for understanding the working principle of pressure and flow control valves starting from their standard hydraulic scheme, - to know the main layouts used for the generation and the control of the hydraulic power, - to know the specific architectures used in multi-actuator hydraulic circuits, - to understand how the theoretical working principles are implemented in real fluid power components. With the skills acquired during the course, students should be able to: - read a fluid power scheme, - know the aim of each component in a fluid power circuit, - analyse qualitatively and quantitatively the different working modes of a fluid power circuit, - understand the technical data from catalogues of fluid power pumps, valves, motors, actuators, - understand how a fluid power valve is able to perform its function, - choose the proper component and its size in relation to its end use, - decide the proper layout of a simple fluid power system for controlling linear and rotary actuators, - contrast different layouts in term of energy saving.

Awareness of basic concepts covered in Physics and Fluid Mechanics.

Main topics are the following: - Fundamentals of Fluid Power (8h): ISO standard 1219, fluid properties, basic flow equations, functional blocks. - Positive displacement pumps (8h): different designs, real steady-state characteristics, kinematic flow rate, volumetric and mechanical-hydraulic efficiencies, source of flow and torque losses, controls for displacement variation. - Fluid Power valves (10h): on-off directional control valves, flow and pressure control valves (pressure relief, pressure reducing, sequence, two-port and three-port flow control), single and double stage types, ideal and real performance characteristics, cartridge valves, analysis of real components. - Accumulators (2h): types, dimensioning criteria and examples of applications. - Flow generation units (6h): constant and variable flow rate (discrete and continuous), constant pressure with absolute pressure limiters (direct acting and piloted) and approximately fixed pressure, ideal and real flow-pressure characteristics. - User groups (15h): mechanical characteristic of linear and rotary actuators (ideal and real), control of overrunning loads in linear and rotary actuators (example of hydraulic winch), flow regeneration in differential actuators, synchronous movement of two linear actuators, orbit motors (with mechanic holding brake and for vehicle traction), speed control of hydraulic motors with flow control valves (meter-in, meter-out, by-pass), parallel/series connection of hydraulic motors for vehicle traction, variable displacement motors (manual control and absolute pressure limiter), hydraulic transformers (pressure and flow amplifiers). - Multi-actuator circuits for mobile systems (8h): open centre and closed centre architectures, load sensing systems with fixed and variable flow generation units, local compensators, flow sharing, example of real circuit of a forklift truck. - Basics of closed circuits (3h): layout of a hydrostatic transmission, electro hydrostatic actuators, closed circuit for differential actuators.

The course is made up of theoretical lectures (the onsite attendance is highly recommended), applied lectures and laboratory sessions. In the applied lectures, some numerical exercises are solved with the assistance of the teacher and the components/circuits used in the laboratory experiences are explained. During the semester, five numerical exercises on simple fluid power circuits will be progressively proposed on the didactic web portal of the Politecnico. This homework must be downloaded and solved individually, according to explicit rules, by all students. The solution of each exercise will be made available two weeks later for a self-correction. The purpose of the homework is twofold: a self-assessment of acquired knowledge and competence; a training route toward the final exam. Students will have to upload on the didactic web portal a scanned copy of their handwritten set of homework within 5 days before the exam (see exam rules). In the laboratory sessions, students have the unique opportunity to see real components donated over the years by different manufactures and to work on their own on some test rigs. Five sessions of laboratory work (1.5 hours each), with compulsory attendance, are carried out in small groups: 1) Pumps and motors: different types of positive displacement pumps and motors (external and internal gear, axial and radial piston and vane machines) are disassembled and analysed. 2) Fluid Power valves: different types of valves such as directional control, pressure relief, pressure reducing, sequence, flow control, piloted non-return are disassembled and analysed. 3) Didactic test rig: students can analyse different circuits and components. Interactions and characteristics of valves and actuators are appraised: the practical setting of pressure control valves, implications in series, parallel and sequential operation of linear actuators, velocity control of rotary motor with constant and variable load. 4) Hydraulic winch test rig. It includes an orbit motor with holding brake and an overcentre valve. The steady-state characteristics of the winch with resistive and overrunning load are measured during the lab experience. Orbit motors are also dismantled and analysed. 5) Load sensing test rig. The test rig, featuring proportional directional control valves and hydrostatic steering unit, reproduces the hydraulic circuit of a forklift truck. It allows energy consumption analyses through data collection of flow rates and pressures. The condition of flow and pressure saturation can also be reproduced. Some load sensing directional control valves are also dismantled and analysed. A technical report involving some calculations starting from the experimental data must be prepared for the laboratory session 4) and 5); the report must be uploaded within 5 days before the exam (see exam rules). Based on availability, a 2-hour seminar could be held with the participation of personnel from a company (manufacturer of fluid power components or systems involving fluid power circuits). Finally, students are invited (optional activity) to reproduce on their own some simple hydraulic circuits using the free Student Edition of Simcenter Amesim; some examples of simulation will be shown during the lectures.

The entire set of slides used during the semester in high quality B/W printed form will be available at the beginning of the didactic term: • Nervegna, Rundo: Mobile and Industrial Fluid Power, EPICS Edizioni, Torino (also available on the eCommerce site – www.centroappunti.it). New improved and corrected reprints are available yearly at the end of February. Moreover, blocks of slides (with possible minor updates) will be progressively made available only to enrolled students on the didactic web portal in electronic and colour version. However, students are strongly invited to integrate the material with their own notes. A glossary with the main Fluid Power terms (English term, equivalent Italian term and short description in English) and the detailed description of the test rigs used in the laboratory experiences will be also uploaded on the web portal. For additional insight into specific topics, reference is made to the following books: • Nervegna, Rundo: Passi nell’Oleodinamica, EPICS Edizioni, Torino, 2020 (in Italian). ISBN 978-88-94802-15-3 (also available on the eCommerce site – www.centroappunti.it). Students enrolled in the course are entitled to a significant discount on the cover price. • Gilardino: Esercizi di Oleodinamica, CLUT, Torino, 2010 (in Italian). • Padovani: Practical exercises about hydraulic components and systems, CLUT, Torino, 2020 (in English). Additional information about the Fluid Power field, the didactics (bibliography, links, testimonials of former students, list of theses, animations and much more) and the research activities can be found on the official web site of the Fluid Power Laboratory (http://www.fprl.polito.it).

Slides; Libro di esercitazione; Esercizi; Video lezioni tratte da anni precedenti; Strumenti di simulazione; Strumenti di auto-valutazione;

Modalità di esame: Prova orale obbligatoria; Elaborato scritto individuale;

Exam: Compulsory oral exam; Individual essay;

... The exam consists of an oral test (up to 26 points out of 30) aimed at assessing the knowledge acquired and the skills listed in the “Expected Learning Outcomes” section and the evaluation of the technical reports (up to 4 points out of 30) about the experimental activities. The oral exam (typically 3 questions) will focus on all concepts and principles exposed during the lectures and laboratory sessions. Candidates must be able to explain the working principle of a component or of a system analysed during the course starting from their hydraulic schemes or 2D/3D drawings, to discuss about advantages and drawbacks of different solutions, to derive analytic governing equations, to obtain and comment steady-state characteristics of the components/systems. A "what to know" list with the level of detail required for each topic will be provided. Moreover, candidates can be asked to make some calculations in a similar way as in the homework or to comment the results obtained in the homework. In case of unjustified absence in the laboratory sessions, additional questions will be asked to check the knowledge of the related topics. No additional point will be awarded for the homework. On the contrary, a penalty up to 2 points can be applied on the final mark in case of incomplete homework. The duration of the oral exam is strictly related to the student’s preparation. The mark will consider the completeness/correctness of the answers, as well as the ability to critically discuss the topics. Generally, the test is a “NO BOOK EXAM”: the use of personal notes, books and manuals in any form is not allowed. However, in specific cases authorized by the teacher, it is possible to consult the teaching material. The mark “30 cum laude” can be obtained in case of maximum mark in the technical report and of an outstanding oral exam demonstrating a very deep knowledge of the subject. If desired, in case of withdrawal, exam failed or rejected mark, the homework and/or the report uploaded on the web portal can be updated with a new version for the next time.

Gli studenti e le studentesse con disabilità o con Disturbi Specifici di Apprendimento (DSA), oltre alla segnalazione tramite procedura informatizzata, sono invitati a comunicare anche direttamente al/la docente titolare dell'insegnamento, con un preavviso non inferiore ad una settimana dall'avvio della sessione d'esame, gli strumenti compensativi concordati con l'Unità Special Needs, al fine di permettere al/la docente la declinazione più idonea in riferimento alla specifica tipologia di esame.