CONDITION MONITORING
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maintenance can be planned, and there
is an opportunity to change only those
parts showing signs of deterioration or
damage. This means that problems can be
detected in advance and maintenance is
performed only when needed.
While the use of remote condition
monitoring is receiving much attention,
these types of systems are often
expensive to retro t. Vibration from
the infrastructure (for example, track
condition, rail joints), contact conditions
at the wheel-rail interface and vehicle
dynamics all make vibration data
interpretation di cult.
And such interpretations are just as
important, if not more so, than collecting
data in the rst place. A misdiagnosis can
lead to the unnecessary removal of trains
or rail vehicles from in-service operation,
resulting in poor asset availability, lost
revenue, high costs and customer
dissatisfaction. A loss of con dence in
such systems can be just as bad as not
having the condition monitoring in the
rst place, and potentially can be more
disruptive to in-service operation.
Instead, T&RS Engineering have
been working closely with several train
operators to extend maintenance and
overhaul intervals, signi cantly reducing
the overall maintenance costs for the
train operators. One of the strategies
adopts an o -line depot-based approach
to condition monitoring using vibration
measurements to assess the condition of
the key assets (traction motor, gearbox
and axlebox) of passenger trains without
the need to remove equipment from the
bogie. This is achieved by rotating the
wheelset on a depot wheel lathe.
ADVANTAGES
The advantages of this type of approach
are signi cant. It can be implemented
quickly for a fraction of the cost of
remote condition monitoring, without any
additions or changes to the bogie; that is,
no additional hardware, sensors or cables.
Furthermore, the potential bene ts of this
approach are huge, enabling equipment
faults and degradation to be detected at
an early stage, maintenance planned, and
costs reduced.
“Optimising railway vehicle maintenance and
overhaul plans to improve availability, reduce
maintenance costs and increase reliability is
becoming increasingly important”
Rolling bearings are a key part
of the drive system of rail vehicles,
and unexpected failure can result in
serious damage to other components
and equipment and loss of operation
in-service. During operation, equipment
reliability is very dependent on the type
of bearing selected, correct installation,
operation and maintenance.
Depot wheel lathes are used by eet
operators to maintain the condition of the
wheel tread, allowing machining of wheel
pro les without the need to remove from
the vehicle. They generally operate in the
range of 60-100m/min, so for a wheel
diameter of 800mm this gives an axle
speed of between 24 and 40rpm. For a
typical reduction gearbox ratio of 4:1, the
traction motor speed would therefore be
between 96rpm and 160rpm respectively.
The big advantage of this type of
approach is that it allows the condition
of the drive system to be easily assessed
while the vehicle is on the wheel lathe
for routine wheel turning. This makes
the whole process extremely simple
and cost-e ective without the need for
large capital investment, installation of
equipment or extensive training. Vibration
measurements are obtained at a constant
speed and the e ects of vehicle dynamics
and the rail infrastructure minimised.
All vibration measurements are
undertaken with the wheel tread
unturned. Unturned wheel treads often
have damage which often takes the form
of wear and fatigue; consequently, the
interaction between the wheel tread and
lathe drive wheel can produce signi cant
levels of vibration. While a turned
wheel tread would result in signi cantly
improved contact conditions at the wheel
tread-drive wheel contact, the interval
between wheel turning may be too long
for trending of vibration. Therefore, all
vibration measurements were carried
out with the wheel tread unturned. This
has the big advantage that trains can be
brought into the depot at an optimum
planned interval and the have the
condition of the drive system assessed.
T&RS Engineering have been working
closely with customers to extend and
optimise overhaul intervals from light
Winter 2021 www.operationsengineer.org.uk 63
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