Arlanda Express train

Arlanda Express. Photo: Arlanda Express/Stefan Andersson

Under the Arlanda Express brand, A-Train operates trains between Arlanda Airport and Stockholm Central in Sweden. After successful test measurements, the company has now invested in the portable instrument Leonova Emerald to measure bearing condition on train wheel bearings.

The test measurements with Leonova were conducted in April 2016 during a test drive where the train ran at a speed of about 160 km/h, with a measured rotational speed of 900 RPM on the wheel shaft. The test setup included four DuoTech accelerometers and one tachometer, and the measurements were carried out using the SPM HD shock pulse technology.

Very clear spectrums indicated an outer ring damage on one of the four measuring points. During follow-up measurements two weeks later, the outer ring frequency signal had increased further. The wheel shaft was dismantled from the train and sent for renovation. When the shaft was disassembled in June 2016, a small but distinct outer ring damage was revealed, entirely in accordance with the analysis of the test measurements.

SPM HD spectrum

The shock pulse measurement shows a perfect hit on the outer ring frequency, with many harmonics. This suggests a small bearing damage, still in an early stage.

Outer ring damage

The outer ring damage.

After the successful test measurements and subsequently confirmed bearing damage, A-Train invested in the portable instrument Leonova Emerald with the patented technologies HD ENV and SPM HD. Despite difficult measurement conditions, the HD technologies provide clear and easy to interpret measurement results at a very early stage of damage development - thus providing optimal conditions for planned maintenance. A-Train has taken delivery of the instrument and maintenance staff has undergone training in its operation.

Arlanda Express is the fastest means of transportation between Stockholm and Arlanda Airport. Trains depart six times per hour during peak hours and every fifteen minutes at other times. The journey takes twenty minutes. The service began in November 1999 and 3.6 million passengers traveled with Arlanda Express in 2016. A-Train is also the infrastructure manager of the Arlandabanan railway line, which, since its inauguration, has enabled more than 70 million people to travel quickly, safely and environmentally between Arlanda Airport and Stockholm City.