Division 4.2.10 Wheel/rail contact

Description of the interface with the infrastructure:

wheel/rail contact has an influence on:

• vehicle running stability,

• the vehicle ride behaviour,

• noise emitted into the environment.

Concerning the first point, the contact geometry shall be such that the stability of running gear is ensured at the highest running speeds.

In relation to the other points, account shall also be taken both of conventional formations (ballast and sleepers), and of ballast-less track which has different characteristics.

The required criteria shall also be complied with for vehicles and equipment with the wear that can be expected to occur on a high-speed network.

This aspect interfaces closely with many parameters within the infrastructure subsystem such as the track gauge, cant deficiency and equivalent conicity.

The different needs of this aspect are translated for this subsystem by the definition of standards for the wheels and axles that comprise the interface points.

The definition of this interface with the infrastructure subsystem allows the ride stability of the rolling stock to be guaranteed in all circumstances and limits of wear of the running gear.

Specification of ride stability criteria:

vehicle ride stability, which is essential for vehicle running safety, depends on the design characteristics of vehicles and more specifically on the wheel-rail contact parameters.

The following characteristics relate to the equivalent conicity defined by the infrastructure subsystem.

Three infrastructure-related parameters determine this:

• the profile of the rail head (e.g. UIC 60, etc.)

• rail inclination (e.g. 1/40, 1/20, etc.)

• track gauge (e.g. 1 435 mm, etc.).

The geometric characteristics of the wheelset (tread profile, gauge of active surfaces, etc.) combined with the three previous parameters generally determines the ride stability to be maintained in the new or worn condition within the range of extreme tolerances permitted for each of these parameters.

Characteristics of the interface elements:

to be accepted for working on the interoperable network, rolling stock shall comply with the criteria on equivalent conicity defined in the infrastructure subsystem, and therefore shall:

1. (c1)

   be fitted with axles fitted with: wheels having a profile in conformity with one of the following:

   • S 1002,

   • GV 1/40,

   distance between internal wheel faces measured at 60 mm below the top of the flange:

   • 1 357 to 1 363 mm for wheel diameter = or > 840 mm,

   • 1 359 to 1 363 mm for wheel diameter < 840 mm,

   distance between active faces of the wheel:

   • 1 410 to 1 426 mm for wheel diameter = or > 840 mm,

   • 1 415 to 1 426 mm for wheel diameter < 840 mm;

2. (c2)

   be subject to acceptance tests in accordance with the provisions in Chapter 6 of the present TSI;

3. (c3)

   to guarantee ride stability under all conditions and protect against failures, have mandatory procedures for periodic checking of the integrity of that equipment by ensuring ride stability (axles, suspension linkages, dampers, etc.);

4. (c4)

   be fitted with an approved device for continuous detection of running gear instability, which shall only be active at speeds in excess of 220 km/h (i.e. in high-speed operation). This device shall advise the driver to reduce speed in the event of instability.

Wear criteria characteristics:

to achieve a proper match between the choice of materials for the rail (as defined in the Infrastructure TSI) and the wheels, the wheels shall use materials defined as follows:

• for the entire zone of wheel rims wear, the values of Brinell hardness (HB) of the material have to be equal or superior (for every measure) to 245,

• if the thickness of the zone of wear is superior to 35 mm, the value of 245 HB has to be obtained until a depth of 35 mm under the bearing surface,

• the value of hardness in the connection between the wheel centre and the wheel rim should be lower at least by 10 points than the measured one on the verge of the range of wear.

Electrical resistance of wheelsets:

to ensure the operation of track circuits, the electrical resistance of each wheelset measured:

• from tyre to tyre,

• in tare condition,

• with a voltage of between 1,8 and 2 volts,

shall be less than:

• 0,01 ohm when new,

• 0,1 ohm after overhaul of the wheelset.

In the case of independent wheels (left and right parallel wheels that rotate independently), it is necessary to electrically connect the pair of wheels to comply with the abovementioned values.