Task

Wheels of vehicles running on rails are subject to high strain. Signs of wear becoming evident in out of round forms, among others, are the conse-quence. Faults of this kind as well as the existence of flat spots, can develop very strong, momentary impacts in the normally homogeneous power transmission from the running wheels to the rails. Possible effects are:

• Increased stress for vehicles and rails causing higher costs for maintenance
• Increased noise pollution and stress due to vibrations
• Reduced travelling comfort
• Consequential damage to vehicles and rails
• Derailments due to wheel damages

Signs of wear due to high stress –identifying in a safe and reliable way.

Solution

The ATLAS system makes it possible to monitor the sets of running and driving wheels of railroad cars in an inexpensive, reliable and continuous way. By the application of strain gauges applied to the tracks, the forces transmitted from the wheel to the superstructure are measured. When a train passes by, faulty wheels are localised and the corresponding data records are produced. By means of a data line, these records are transmitted to a control centre, where alarm messages display the faulty wheels together with their correspond-ing position in less than a second. Apart from localising faulty wheels, the ATLAS system can also be used as dynamic track scales to record weight and load status during the passage.

System Components

1 Sensors for force measurement
The forces transmitted from the wheel into the rail are directly recorded by means of strain gauges. For that process, the characteristic
feature that deformations change the electric resistance is taken advantage of.

2 Service & Communication Terminal (SCT)
The main component is a powerful IPC, which has been designed for extremely rough environmental conditions. From that IPC, all the maintenance and test functions of the measuring system connected can be carried out. The measuring data obtained are then processed in such a way – by applying a special algorithm – that the weight and the geometric wheel faults are evaluated and displayed for each wheel individually. In addition, the SCT is used as an interface to the higher network structure (e.g. TCP/IP) and can be integrated into various topologies.

3 Central record and control unit
For the integration of several measuring points as well as of other registration systems, a central record and control unit can be used optionally. Here again, the integration into different network topologies and network protocols is possible.

4 Remote Service Terminal (RST)
All the maintenance and test functions of the ATLAS system can be carried out worldwide via a remote service function. This leads to a further decrease in operational costs.

5 Maintenance-Service
Also Service and maintenance is offered to monitor, configure and maintain
client systems on request.

Innovative Measuring Technology

The stationary installation of the system has been designed for recording the true running
characteristics of wheels, but it can also be used as dynamic scales. The measuring principle of the localisation of flat spots is based on the following facts: Measurements are carried out on all force-abducting spots at the same time by
means of strain gauges. The sum of all forces is the Q-force. The dynamic effect of a wheel is recorded for the entire girth of the wheel. Forces of neighbouring wheels are separated by slotting separate measuring strips into each other. This particular measuring procedure helps to considerably increase safety and optimize
the servicing of wheel sets.

Basic Construction of a Measuring Point

R = Measurement of the reaction force of the sleeper, where – for the compensation of the influence of the road bed – that part of the Q-force is measured which has an effect on the individual sleeper
T = Thrust measurement,
It is the beginning and the end of a measuring strip. The dynamic coefficient – to be drawn from the following formula – gives information
on the status of the wheel (the higher this coefficient, the higher is the degree of wear of the wheel).
Dyn. Coefficient = (Qstat + Qmax) / Qstat

Due to the fact that ATLAS is able to scan the ENTIRE WHEEL GIRTH, it is possible to detect all sorts of geometric faults which might develop. High-speed trains (ICE) going at speeds of more than 300km/h, but also freight trains going at much lower speeds can be measured.

Maintenance costs are reduced by early and pointed diagnoses of wheel sets
Costs for servicing the tracks are reduced
Running life of wheel bearings is increased
Travelling comfort is increased
Noise pollution is reduced
Checking the load status (leaning loads / overloads)
Optimal use of load capacities
Prevention of derailments
Continuous registration of the entire wheel girth
Flexible network integration
Safe data transmission
Remote servicing concept
Tamping is possible without de-installing the system

Max. number of axles	1000
Speed scope	60 - 500 km/h (tested up to 350 km/h)
Temperature scope	– 30 to + 70°C
Exactness of scales	+ / -5 %
Weight measuring range	1t to 70t per wheel
Intervals for calibration	once a year (recommended at present)
Length of measuring strip	approx. 4 m, can be longer or shorter on demand
Max. wheel diametre	all the usual wheel diametres can be recorded continuously
Min. axle distance	0.7 m
Train speed	Train speed is determined with an exactness of 1.0 %
Technology applied	direct force measurement by means of strain gauges