Dr D Wehrhahn - Non-Contact Laser Systems for the Railway Industry

Dr. D. Wehrhahn specialises in developing and manufacturing laser systems for the railway industry. Its product range encompasses standard laser probes, specially developed customised sensors and complete measuring systems with laser, mechanics and software.

OPTImess laser sensors are a universal measuring instrument for railways due to their small size, high measuring frequency and accuracy, and their ability to measure under almost any ambient conditions.

WHEEL PROFILE MEASUREMENT

The OPTImess compact, laser-based measuring instrument ensures that the profile data of wheels are selected and measured reliably. The measuring system is battery-operated with a data logger as an input and memory medium.

Measurements on the wheel and assessment of wear can be performed quickly and easily. The characteristic variables such as wheel flange thickness, wheel flange height, wheel flange width, flange angle and wheel gauge are measured. These systems, which are also used on tramways and underground railways, were developed in co-operation with German Railways.

WHEEL SET MEASURING STANDS

If only the characteristic variables of the wheel profile are determined in the application described above, the use of several sensors on a two or three axle drive unit allows almost all parameters of the wheel set, such as profile, impact, brake disks, and flattening to be measured.

All parameters to be measured are determined, measured automatically and logged by entering the wheel set identification. The flexibility of the laser sensor in terms of dimensions, measuring distance and measuring range also allows the conversion or retrofitting of existing tactile measuring stands.

IN TRACK WHEEL PROFILE MEASURING SYSTEM

The automatic wheel profile-measuring device is used to measure the wheel profile and diameter whilst a tramway vehicle drives slowly over the measuring system. The use of non-contact laser measuring technology guarantees a high resolution and accuracy in the recording of the whole wheel profile. All the dimensions necessary for a qualitative wear assessment of the wheel are determined and displayed with the aid of the evaluation software.

This measuring system was designed under special consideration of existing space conditions with the use of low-platform vehicles.

RAILMONITOR- A WORLD FIRST IN MOBILE RAIL MEASUREMENT

The RAILMONITOR combines non-contact laser measuring technology with an integrated TFT screen and integrated computing software, for all the parameters required for grinding including comparison with standard profiles.

The RAILMONITOR saves on time and costs as its measuring time, including setting down, measuring and evaluation, comes to less than 20s/profile.

Its measuring range and total construction allows Vignol, and grooved rails and points including tongues to be measured. The determined measuring curves are displayed immediately on the integrated TFT screen and saved on a CompactFlash card.

RAIL PROFILE MEASUREMENT

To classify of the state of wear of the rail head, and evaluate the necessary maintenance work, measuring vehicles equipped with laser sensors, in which five to seven sensors per rail side are positioned around the rail head, are used. Measured values are recorded every 20cm at these points, at about 80mph, and compared with the nominal profile in the computer. The computer classifies the deviations according to given tolerance values.

CONTACT WIRE MEASUREMENT

The OPTImess system involves a laser triangulation scanner that measures the height and lateral position of the contact wire during travel. Another five laser sensors are installed on the vehicle to measure the inclination of the carriage, the lateral movement of the carriage, and the track width. All of this data is displayed graphically and logged.

The OPTImess measuring system operates under almost all conditions including rain, extreme heat and frost.