The course will address the following main areas:
- TYPES OF ROLLING STOCK
- Wheelsets
- Bogie frames
- transmission to the wheels
- SUSPENSIONS
- Carbodies
- TRACTION/REPULSION COMPONENTS
- BRAKING
For more details on course topics, see the detailed program.
Please contact Prof. Andrea Bracciali at andrea.bracciali@unifi.it for a list of English textbooks on the subject
Learning Objectives
Provide the Mechanical Engineer students the information concerning the design and operation of railway, tramway and suburban rolling stock, with particular reference to the interaction of the vehicle with the infrastructure (track and signaling).
Ability to understand in detail the mechanics of rail vehicles. Ability to identify the loads acting on structures and to carry out a proper design.
CA2: Applying knowledge and understanding related to the analysis and optimization of mechanical devices and systems, as well as to their innovation also through the development and improvement of design methods, constantly confronting with the rapid evolution of mechanical engineering.
CA4: Applying knowledge and understanding related to the implementation of engineering projects adapted to their level of knowledge and understanding, working in collaboration with engineers and non-engineers. The projects may concern components, equipment and mechanical systems of various kinds and for the widest possible applications.
CA12: Applying adequate knowledge and understanding to understand English texts.
CA15: Applying knowledge and understanding to achieve adequate preparation for tertiary level university studies (frequency to post-master's degree courses and doctoral schools) in order to further deepen knowledge and skills in research.
CC1: In-depth knowledge and understanding of the theoretical-scientific aspects of engineering, with a specific reference to mechanical engineering, in which students are able to identify, formulate and solve, even in an innovative way, complex and/or interdisciplinary problems. The ability to understand a multidisciplinary context in the engineering field and to work with a problem solving approach
Prerequisites
Knowledge of Manufacturing technologies, Applied mechanics, Machine Design. Basic knowledge of vehicle dynamics
Teaching Methods
Classroom lessons + visit to industrial workshops if compatible with the lessons
Type of Assessment
Oral exam
Course program
Historical background to railway traction. Running resistances. Power requirements. Types of locomotives and possible overloads. Diagram of a train running
Greening railways: C02 production, noise, vibration, electromagnetic interference. European standards and impact on the design of the rail system.
TYPES OF ROLLING STOCK
Architecture of the rail vehicle (two wheelsets, with bogies): wheelsets, suspensions (primary and secondary), bogie (if applicable), carbody, traction and repulsion organs (hook and buffers).
Locomotives
Towed vehicles (freight wagons and passenger coaches)
Diesel and Electrical Multiple Units. Push-pull trains: remote control of locomotives. Compositions with multiple traction on the head, asymmetric, symmetric.
Distributed power high-speed rolling stock(ETR4X0, ETR6X0) and with locomotives (ETR 500).
Tram and metro vehicles.
WHEELSETS
Morphological description of the wheelsets with monobloc or tyred wheels, with block or disc braking.
Wheelset/bogie frame connection.
Calculation of wheelsets (wheels, axles, bearings) according to EN standards. Qualification tests and validation of the design.
BOGIE FRAMES
Morphological description of the main types of bogies. Rigid wheelbase, curve negotiation. Track twisted. Ratio Y/Q. Articulated bogie frames. Bogies for trams and metros.
Bogie frame / carbody connection
Calculation of the bogie frame according to EN. Qualification tests and validation of the design.
TRANSMISSION OF MOTION TO THE WHEELS
Architecture of the motor bogies with electric traction motors: nose (tram) suspension, hollow axle, Hooke joints and shafts. Gearboxes. Non-conventional systems for tram and metro vehicles.
Architecture of motor bogies with diesel engines and mechanical transmission: gearbox, clutch, sliding coupling, torque converters.
Architecture of motor bogies with diesel electric and electrical trasmission: the generator / alternator, control characteristics
SUSPENSIONS
Leaf spring suspension
Coil springs, the calculation of the helical spring (compression) fatigue in coil springs. Secondary suspension coil springs, transverse stiffness calculation.
Rubber elements, stiffness in compression, in shear and conical. Characteristic of a spring made of elastomeres and a helical spring.
Air suspensions, suspensions with rubber elements, description of the systems.
Viscous and friction dampers.
CARBODIES
Steel carbody structures: spars, masts, currents, coating sheets.
Aluminium carbodies made of light alloy extruded profiles: brief descriptions, advantages and disadvantages.
Ports and related safety equipment. Bodies of intercommunication.
Speakers vehicles plan in full or partially lowered.
Calculation of the carbodies according to EN. Qualification tests and validation of the design.
TRACTION AND REPULSION ORGANS
Connection between vehicles. Mechanical, pneumatic, electrical connections.
Traditional hook with tensioner: description of the components and features, behaviour in terms of traction. Description of the "castle of traction". European Standards / UIC on hooks.
Buffers with elastic elements in steel, rubber and fluid.
Janney Automatic hook, Willison automatic hook. Outline of UIC automatic place on the hook and reasons for non-introduction. Voith Scharfenberg automatic hooks for light vehicles.
BRAKING
Requirements of train braking. Vacuum braking.
Braking system components, linkages, play recovery devices, brake shoes, discs, brake cylinders.
Direct brake. Automatic vacuum vacuum (general scheme, distributor).
High-speed braking, the trend of the coefficients of friction with speed, pressure limiter valves.
Issues relating to traditional vacuum brake, brakes EP.
Braking mass. European Standards / UIC on braking. Qualification tests and validation of the design