SJ embraces remote bearing monitoring

November 2014 | Railway Gazette International
SJ embraces remote
bearing monitoring
Commercial Director
Perpetuum Ltd
ith SJ facing competition on its busiest
inter-city corridor from
next March (p55), the
operator has launched a mid-life refurbishment programme to update its 43
SJ2000 tilting inter-city trains.
One novel aspect of the work is the
installation of 40 sets of Perpetuum’s
bearing and wheelset monitoring equipment on both powered and trailer
wheelsets. At the heart of this technology is a novel vibration harvester, which
converts vibration into a reliable electrical energy supply. It was developed by
academics at the University of Southampton, who established Perpetuum in
2004 as a means to commercialise their
research. Although initially targeted at
the industrial sector, the harvester later
found a more compelling application in
the high-vibration railway environment.
For the last four years, Perpetuum has
been developing self-powered sensors
that can be mounted directly onto bogie
components, and a set of algorithms that
can drive condition-based maintenance
Early adopter
As reported in RG 9.13 p75, Perpetuum received its first major order from
UK operator Southeastern, which was
keen to ensure its maintenance teams
had accurate information on the status
and remaining life of the components.
Southeastern fitted Perpetuum’s wireless
Sweden’s national operator is deploying Perpetuum’s novel vibration
harvesting technology to improve wheelset reliability on its SJ2000
inter-city fleet, which is now being refurbished.
Above: SJ’s X2000
tilting train
fleet is going
through a mid-life
Inset: A Perpetuum
wireless bearing
sensor as fitted
to a Bombardier
EMU operated by
Southeastern in
the UK.
sensors to more than 600 vehicles within three months, thanks to the 20 min
fitting time per sensor. Subsequently,
Southeastern has received safety case
approval to introduce a condition-based
maintenance regime for axle bearings
which should deliver seven-figure sums
per year in maintenance efficiencies.
SJ’s adoption of the technology comes
as a result of an extensive investigation
into the level of work needed to ensure
the SJ2000 is fit for purpose for the next
several years. The operator is looking
to reduce operating costs by extending
wheelset overhaul period beyond its current scheduled limit, partly because it
believes that a small proportion of the
vehicles in the fleet is responsible for a
perception of short wheelset life and a
lack of component reliability.
The various different maintenance
regimes, sub-assemblies and operating patterns over the past 20 years have
compounded the problem of fully understanding the variances in bearing life
across the different vehicles. As wheelset
overhaul is being driven by the unpredictable performance of the bearings, it
follows that by monitoring the bearing
condition SJ should be able to run the
trains safely until a change in vibration
condition passes the calibrated threshold. Perpetuum expects its analysis tool
to spot this breach three months before
any non-vibration based monitoring
We are currently at the calibration
stage where algorithms are tuned for the
specific fleet, operating conditions and
components, to ensure that the Bearing
Health Index is 100% reliable.
For the SJ contract, Perpetuum has
taken additional measures to protect
the sensors in harsh winter conditions,
which can include snow compacting,
ice formation and frozen ballast strikes.
Perpetuum has developed a poly-composite casing, manufactured from the
same PEX material used to protect the
SJ2000 axles. The casing has been designed with two key targets in mind: a
reduction in the risk of higher moments
on the bearing cover sensor brackets,
and the shielding of the 433 MHz data
transmission from the sensor. The sensors were subjected to -30°C under high
accelerated life testing conditions, designed to destroy the components, and
they performed very well. The antenna
was also encased in ice to test the communications from the sensors to the onboard data concentrator, with no significant loss in performance being recorded.
Perpetuum has found its experience
in exporting UK technology to Scandinavia to be very positive, with the
local industry willing to embrace condition-based maintenance and remote
condition monitoring. But if this year’s
InnoTrans show was anything to go by,
there is the real prospect of uptake from
other large railways around the world,
including those in China, India, Russia
and South Korea. n