Laser profile sensors measure conductor rail wear and track gauge

In the railway industry, an important aspect is the aftermarket rail inspection for wear monitoring, recording and track bed geometry. 

Donfabs & Consillia Ltd provides complete solutions for railway monitoring, producing a full range of equipment for the measurement of a wide variety of track parameters. 

The company’s product portfolio covers everything from unattended units for recording ride comfort, through to track parameter measurement together with vehicles for rail inspection and maintenance.

One of the company’s latest projects was the measurement of the track bed geometry with a large overseas Railway Network. 

The task was to measure the wear on the power rail to ensure it was not worn beyond the conductor rail. This would cause a loss of connection and stuttering of the train, which in turn leads to disruptions and an uncomfortable ride for commuters. 

Previously, the track bed geometry was checked through visual inspection by the operator. This manual process was susceptible to human error and excessive wear could go unnoticed resulting in the rail disruption.

Inspecting for signs of wear

To identify this problem and implement a more reliable solution, Donfabs & Consillia constructed a maintenance vehicle that utilised the Micro-Epsilon scanCONTROL laser profile sensor to look for signs of wear. 

The inspection rides take place outside, so the sensors have to withstand harsh conditions such as dust, oil and rain. 

Moreover, the target material can be both dull and shiny aluminium or stainless steel, which causes difficult reflection quality.

A total of six scanCONTROL LLT2910-100 laser profile sensors with 100mm wide laser lines are mounted on the sides of the main carriage, looking up, down and from the side at the rails. The wide measurement range in width and depth allowed for great flexibility of each sensor position so that they could be fixed and did not have to move. 

Due to the functionality of the scanCONTROL Configuration Tools Software, each sensor could be configured for a number of measurements. This made it easy to find measured values for gauge of the guideway, widths of top and bottom rail, as well as height of guideway on both sides. 

In addition, the software and parameter settings simplified integration. Defining analogue outputs for each measurement point allowed the combination of measurements from each sensor in the host controller to calculate the gauge of the track and the power rail wear measurement.

With this solution, a continuous and non-contact measurement during the movement of the vehicle is possible. The whole system is transportable, lightweight and easy to setup. This enables a much faster and more reliable inspection than the previous visual control.

Ian Moss, Sales Director at Donfabs & Consillia commented: “The introduction of these laser profile sensors has certainly provided some clever solutions to this measurement requirement.”

Graham Limb, Technical Director at Donfabs & Consillia added: “The support from Micro-Epsilon during the specification of this project has been invaluable and their technical assistance one of the keys to the success of this project.”