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Fluid Machines
First semester
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Learning outcomes of the course unit

Knowledge and ability to understand
Through the lectures given during the course, the student will acquire the knowledge necessary to understand both the operation of the main components and hydraulic machines and the functionality of the circuits in which they are inserted.
Ability to apply knowledge and understanding
Through classroom exercises, with the help of a simulation software used actively by each student, students learn how to apply the acquired knowledge.
Evaluation autonomy
The student should be able to understand and evaluate the operation of the hydraulic circuits critically, he should be able to propose which machine and component is more suitable to obtain the required functionality.
Communication skills
Through the frontal lessons the student acquires the specific vocabulary inherent to the oleodinamic systems (fluid power systems). It is expected that at the end of the course the student will be able to convey the main contents of the course, such as ideas, engineering issues and related solutions, in oral and written form.
Learning ability
The student who has attended the course will be able to deepen his knowledge through the autonomous consultation of specialized texts, scientific or dissemination journals, even outside lecture topics, in order to effectively address the inclusion in the labour market or undertake further training paths.


Fluid Machinery

Course contents summary

The course presents the analysis of both fluid power components and systems. The main components of hydraulic circuits are presented, focusing on the working principles and the design criteria. Several hydraulic circuits are analyzed, taking remark from the most common industrial applications. Many numerical exercises are solved, some of them by means of numerical computer simulations.

Course contents

Hydraulic symbols.
ISO1219 specifications: basic symbols and combinations.
Fundamental equations – hydraulic fluids
Orifice equation. Orifice for metering and pressure modulation. Physical properties of hydraulic fluids. Fluid damping effects of an orifice.
Positive displacement Pump and Motors
Different designs. Displacement control devices for variable displacement machines. Global, volumetric and hydro-mechanical efficiency. Measurement techniques to evaluate the global efficiency.
Control components in hydraulic systems
Pressure control valves. Direct acting and hydraulically piloted relief valves. Actual and ideal flow characteristics. Sequence valves. Differential and proportional valves. Pressure reducing valves
Flow control valves. Orifices, compensated flow regulators, flow dividers and combiners Two ways and three ways flow control valves.
Directional control valves. Load sensing flow sharing Valves. Overlap: definition and effects on the valve behavior. On/off and proportional control valves. Check valves.
Power units
Constant flow rate power unit. Flow-pressure characteristics.
Discrete values variable flow rate power unit. Flow-pressure characteristics and evaluation of the group efficiency. Use of a remote piloted relief valve.
Variable flow rate power unit. Flow-pressure characteristics.
Fixed pressure power unit. Flow-pressure characteristics. Power unit at fixed pressure with fixed displacement pump.
Hydraulic uses
Control of the dragging loads: counterbalance and overcentre valves.
Control of the actuators speed with multiple load conditions.
Load Sensing Systems
Load sensing system controlling several units with fixed and variable displacement pumps. Energy saving and controllability of LS systems . Pressure compensators. Priority valve. Analysis of complex circuit: excavator; telehandler.
Open centre hydraulic systems
Negative flow control. Positive flow control. Flow summation.
Anti-lock brakes and traction control
Type of anti-lock brake systems, modulating principles. Vehicle dynamic control system.
Hydrostatic transmissions
Working principles and application field. Open circuit and closed circuit hydrostatic transmissions. Elements of a closed circuit hydrostatic transmission.
Servo systems
A short overview of power steering.

Recommended readings

All the material presented during the lectures and exercises is made available to students on the Elly platform.
Students are invited to consult the following textbooks:
N. Nervegna, M. Rundo, “Passi nell'Oleodinamica”, 2 volumi, Politeko, Torino
Autori vari, 2007, “Hydraulics in Industrial and Mobile Applications”, ASSOFLUID
M.G. Rabie “Fluid power engineering” Mc Graw Hill

Teaching methods

The course has 6 CFU which correspond to 48 hours of teaching activity. The didactic activities will be conducted for about 30 hours of lectures, the subsequent hours will be carried out using simulation software. Ten workstations are available for single student or couple of students.
During lectures the main topics are presented form a theoretical-design point of view in order to deepen understanding of the themes by the students.
Educational visits are planned at manufacturer of hydraulic components.
The slides used to support the lessons will be uploaded to the beginning of the course on the Elly platform.
To download the slides, you need to enroll in the online course.
Slides are considered an integral part of teaching material.

Assessment methods and criteria

There is only the final exam that ensures the acquisition of knowledge and skills by conducting an oral test.
To be admitted to the oral examination the student must have completed a short project to be carried out with the software presented during the exercises. The project is assigned during the last lesson of the course, considering the average number of students, at each student is assigned a different project. Students are invited to carry out the project in collaboration, discussing about the specific issues involving their project.
The student must send the report relating his project, via email, at least one week before the oral examination.
There is no vote for the project, but only the admission to the oral test.
Honors is given in case of achieving the highest score on each item, the mastery of vocabulary is required.
These information are reported on the Elly platform.

Other informations

Lecture attendances is highly recommended.. Participation in lessons when the use of the simulation software is taught is indispensable.