Wheel slide protection testing

Wheel slide protection (WSP) is a brake system that optimises available adhesion to minimise braking distance, preventing wheels from locking. It plays a crucial role in maintaining safe and efficient rail operations. 

Wheel slide protection testing is required both for WSP system certification and WSP vehicle integration during vehicle homologation.

It can be performed either through on-track tests by lowering the wheel/rail adhesion using bio-degradable soap or oil, or through hardware-in-the-loop simulation tests by simulating low wheel/rail adhesion conditions. The extent to which on-track or simulation tests may be used during homologation depends on the applicable standards and regulations, most importantly EN 15595 and UIC 541-05.

TÜV SÜD provides both on-track and simulation testing services for wheel slide protection systems, accredited according to ISO 17025. This way, we can offer you independent and efficient testing.

Due to its nature, on-track testing of wheel slide protection is more exposed than other testing steps to several influencing factors that are relatively hard to control and could potentially lead to costly delays in the homologation process.

Among those factors are limited track availability for tests which require lowering the wheel/rail adhesion, or track and weather conditions which are not well suited for WSP testing. This becomes even more critical when it is necessary to tune WSP parameters during on-track commissioning tests before homologation tests.

At TÜV SÜD, we have decades of experience in extensive testing services for rolling stock and railway components. This includes wheel slide protection testing through our facilities in Germany and Switzerland and our roster of experts worldwide.

Our facilities are accredited according to the ISO 17025 standard, ensuring impartial and reliable results. 

In addition to WSP on-track testing, we offer complementary hardware-in-the-loop WSP simulation testing services that can contribute to a simplified and more reliable planning of WSP test campaigns. At the same time, they can help to save traction energy and staff for dynamic on-track testing.

TÜV SÜD conducts real-time WSP simulation testing using a mobile hardware-in-the-loop test bench on the vehicle. Our test bench system uses distributed axle speed simulation modules which are connected to the WSP control units integrated within the vehicle. This setup is well suited to equip also longer vehicles with several WSP units at the same time. The TÜV SÜD axle speed simulation modules are capable to simulate various common types of sensors used in the rail industry, including their lifesign signals and dual-channel sensors with phase shift.

Using the mobile hardware-in-the-loop test bench, we can simulate dynamic WSP tests while the vehicle is in standstill. Meanwhile, its brake and WSP system are acting as if the vehicle would run, with the brake forces being regulated by the WSP in reaction to simulated wheel/rail adhesion conditions. Quantities related to the brake application forces (e.g. pneumatic or hydraulic pressures) are recorded and fed back into the simulation to calculate the deceleration behaviour of the vehicle.

In addition, with this system we can also perform tests of wheel rotation monitoring systems / systems for detection of non-rotating axles through open-loop simulations of artificial axle speeds.