Bogie parts with description Bogie Frame. Steel plate or cast steel. Here is a modern design of welded steel box format where the structure is formed into hollow sections of the required shape. Bogie Transom. Transverse structural member of bogie frame (usually two off) which also supports the car body guidance parts and the traction motors. Brake Cylinder. When air is admitted into them, the internal piston moves links attached to the piston and causes the brake pads to press against the discs. Brake disc. Each wheel is provided with a brake disc on each side and a brake pad actuated by the brake cylinder. Some bogies have two brake cylinders per wheel for heavy duty braking requirements. Primary Suspension Coil. A steel coil spring, two of which are fitted to each axle box in this design. They carry the weight of the bogie frame and anything attached to it. Motor Suspension Tube. Many motors are suspended between the transom and the axle. This motor is called "nose suspended" because it is hung between the suspension tube and a single mounting on the bogie transom called the nose. Gearbox. This contains the pinion and gearwheel which connects the drive from the armature to the axle. Lifting Lug. Allows the bogie to be lifted by a crane without the need to tie chains or ropes around the frame. Motor. Normally, each axle has its own motor. It drives the axle through the gearbox. Some designs, particularly on tramcars, use a motor to drive two axles Secondary Suspension Air Bag. Rubber air suspension bags are the secondary suspension system. The air is supplied from the train's compressed air system. Wheel Slide Protection System Lead to Axlebox. Where a Wheel Slide Protection (WSP) system is fitted, axleboxes are fitted with speed sensors. These are connected by means of a cable attached to the WSP box cover on the axle end. Shock Absorber. To reduce the effects of vibration occurring as a result of the wheel/rail interface.
Conventional and steering truck On very sharp curves, the wheel flanges (bordini) contact the rails at an angle, an not only do they wear each other but they also produce a lot of unpleasant noise and vibration. Flexible in longitudinal direction If the axles are allowed some freedom this wear and noise is reduced, but safety at speed is also reduced. Less wear on flanges and rails occurs at the expense of a more complicated suspension system, with more joints in the bogie mechanism
Alignment of link-type forced steering bogie Bogie frame Steering beam Steering lever and linkage
Maximum lateral force kN 50 40 60 30 50 60708090100 110 speed km/h Non steering bogie Steering bogie Radius of curvature 302 m
Wheel flange wear standard “stiff” bogies Radial steering bogies
Advantages based on experience State-of-the-art radial self-steering bogies are able to steer approx radially in curves of R= 400-600 m. However, on many networks such curves are decisive for the accumulated wheel and rail wear. This is proved in practical trains services to reduce lateral forces, to heavily reduce wheel and rail wear and to increase lateral curving acceleration. With appropriate damping (especially hydraulic yaw damping) running stability is assured at various values of eq. conicity. At the highest speeds (250 km/h + 10 %) conicity should be limited to 0.3 à 0.4(UIC 518 requires 0.3). Testing and experience confirm theory and simulations.
Limitations High tractive forces may limit the radial steering capability, because radial self-steering is depending on a certain amount of friction (creep) forces. In high-adhesion locomotives radial self steering can not always be managed. In local/regional trains with adhesion utilization of 15 -17 % the radial performance will be appropriate in practice, because high adhesion is only applied occasionally at acceleration at low speed.
Future outlook Marginal cost for track deterioration should be included in the track access charges on a number of European railway networks. This sharpens the need for ”track- friendly” bogies. Ongoing development seems to widen the application of self-steering bogies to higher speed (250 km/h and up). Many high-speed trains will be running on various track standards at various speeds, in particular tilting trains. Actively controlled radial steering–”Mechatronic bogies”- may be considered as an appropriate mean to achieve still higher performance and track-friendliness. Once active control is robust, fail-safe and affordable, such solutions may be very attractive.
Prestazioni dei freni ad attrito Il freno è composto da un elemento mobile (tamburo o disco) calettato rigidamente alla ruota (o al cerchione o all’asse porta ruota) e da un elemento fisso solidale al telaio del veicolo. L’applicazione della forza normale P1 alla superficie di contatto fra i due elementi provoca il sorgere di una forza di attrito tangenziale Ft fra di loro.