Dr D Wehrhahn
Non-Contact Measuring Systems for the Railway Industry
Dr D Wehrhahn specialises in railway industry laser systems, including 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.
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.
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 line measuring system with DB approval
The OVHWizard is a non-tactile contact line measuring system for determining the contact line height and stagger with and without uplift. The system operates with ultrasound according to the principle of runtime measurement. This measuring principle offers the advantage over optically operating systems that it also works in direct sunlight, light rain or fog. Thanks to its weight of approximately 4kg, it is easy to handle and can be installed on every vehicle roof with a few actions. A simple RS232 connection to the PC or laptop enables communication with the measuring software.
A pulse transmitter of the vehicle or a light barrier and self-adhesive reflectors for attaching to the wheel can be used for determining the distance. The measured data are displayed online, recorded and shown and saved in graph or table form by means of the included software. The postprocessing enables the measuring runs to be evaluated locally or at the office.
The system can be equipped with an optional camera system. The condition of the contact wire is recorded parallel to the measurement. The measured values for height and stagger are shown in the on-screen image. The image of the contact wire is available for every measured value for later observation of the measured values.
The measured data can be evaluated extensively later with the FMA software developed jointly with Siemens. The measurement can be correlated with existing line data. In addition it is possible to show every dropper of the measured line and list the deviations at each of these points next to the design in a table. This function enables the service teams to move exactly to the affected positions and make the specified corrections. In addition to the measured data for height and stagger the wind drift, longitudinal span, elasticity and other values relevant to the contact wire are calculated.
The system is in use on measuring trolleys, two-way vehicles, service vehicles (MTW) and measuring trains. The system can be delivered with optional compensation of the vehicle movements.
The system has had DB approval since February 2010.