IEC TR 62131-3:2011

IEC/TR 62131-3 ®
Edition 1.0 2011-02
TECHNICAL
REPORT
colour
inside
Environmental conditions – Vibration and shock of electrotechnical equipment –
Part 3: Equipment transported in rail vehicles

IEC/TR 62131-3:2011(E)
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IEC/TR 62131-3 ®
Edition 1.0 2011-02
TECHNICAL
REPORT
colour
inside
Environmental conditions – Vibration and shock of electrotechnical equipment –
Part 3: Equipment transported in rail vehicles

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
X
ICS 19.040 ISBN 978-2-88912-388-9

– 2 – TR 62131-3  IEC:2011(E)
CONTENTS
FOREWORD . 5
1 Scope . 7
2 Normative references. 7
3 Data source and quality . 8
3.1 UK rail measurements . 8
3.2 Association of American Railroads – Lengthways shocks . 9
3.3 Association of American Railroads – Intermodal environment . 10
3.4 Association of American Railroads – Study of the shock and vibration
environment in boxcars . 10
3.5 Association of American Railroads – Study of the railroad shock and vibration
environment for railroader equipment . 11
3.6 Supplementary data . 11
4 Intra data source comparison . 12
4.1 General remark . 12
4.2 UK Rail measurements . 12
4.3 Association of American Railroads – Lengthways shocks . 13
4.4 Association of American Railroads – Intermodal environment . 13
4.5 Association of American Railroads – Study of the shock and vibration
environment in boxcars . 14
4.6 Association of American Railroads – Study of the railroad shock and vibration
environment for railroader equipment . 14
4.7 Supplementary data . 15
5 Inter data source comparison . 15
6 Environmental description . 17
7 Comparison with IEC 60721 . 18
8 Recommendations . 20
Bibliography . 49

Figure 1 – British Rail measured vertical vibration severities . 22
Figure 2 – British Rail measured lateral vibration severities . 22
Figure 3 – British Rail measurements distribution of shunting velocities . 23
Figure 4 – Association of American Railroads – Lengthways shock measurements –
example shock pulses . 24
Figure 5 – Association of American Railroads – Lengthways shock measurements –
comparison of positive peak acceleration . 25
Figure 6 – Association of American Railroads – Lengthways shock measurements –
comparison of negative peak acceleration . 25
Figure 7 – Association of American Railroads – Lengthways shock measurements –
comparison of rms acceleration . 26
Figure 8 – Association of American Railroads – Lengthways shock measurements –
comparison of crest factor . 26
Figure 9 – Association of American Railroads – Lengthways shock measurements –
comparison of change of velocity . 27
Figure 10 – Association of American Railroads – Lengthways shock measurements –
comparison of filtered peak acceleration . 27
Figure 11 – Association of American Railroads – Intermodal study - amplitude
probability in longitudinal axis . 28

TR 62131-3  IEC:2011(E) – 3 –
Figure 12 – Association of American Railroads intermodal study – amplitude probability
in lateral axis . 29
Figure 13 – Association of American Railroads intermodal study – amplitude probability
in vertical axis . 30
Figure 14 – Association of American Railroads – Intermodal study – vertical axis
spectral values . 32
Figure 15 – Association of American Railroads – Intermodal study – lateral axis spectral
values . 32
Figure 16 – Association of American Railroads – Intermodal study – longitudinal axis
spectral values . 33
Figure 17 – Association of American Railroads – Boxcar measurements – vertical axis
spectral values . 33
Figure 18 – Association of American Railroads – Boxcar measurements – lateral axis
spectral values . 34
Figure 19 – Association of American Railroads – Boxcar measurements – longitudinal
axis spectral values . 34
Figure 20 – Association of American Railroads – Cushioned boxcar measurements –
middle of car . 35
Figure 21 – Association of American Railroads – Cushioned boxcar measurements –
end of car . 35
Figure 22 – Association of American Railroads – Standard boxcar measurements –
middle of car . 36
Figure 23 – Association of American Railroads – Standard boxcar measurements – end
of car . 36
Figure 24 – Association of American Railroads – Railroader measurements – peak
spectral value. 37
Figure 25 – Association of American Railroads – Railroader measurements – amplitude
probabilities . 38
Figure 26 – Johnson – Reported measurements – spring buffers . 39
Figure 27 – Johnson – Reported measurements hydraulic buffers . 39
Figure 28 – Johnson – Reported measurements – probability of occurance . 40
Figure 29 – Foley – Reported measurements – frequency distribution . 40
Figure 30 – Foley – Reported measurements – recurrent events . 41
Figure 31 – Foley – Reported measurements – intermittent events . 41
Figure 32 – GAM-EG-13 – Reported measurements – longitudinal axis . 42
Figure 33 – GAM-EG-13 – Reported measurements – lateral axis . 42
Figure 34 – GAM-EG-13 – Reported measurements – vertical axis . 43
Figure 35 – GAM-EG-13 – Reported measurements - longitudinal shocks . 43
Figure 36 – GAM-EG-13 – Reported measurements– vertical shocks . 44
Figure 37 – ASTM D4728-95 – Reported measurements . 44
Figure 38 – IEC 60721-3-2 (1997) – Random vibration severity . 45
Figure 39 – IEC 60721-4-2 (1997) – Random vibration severity . 45
Figure 40 – IEC 60721-3-2 (1997) – Sinusoidal vibration severity . 46
Figure 41 – IEC 60721-4-2 (1997) – Sinusoidal vibration severity . 46
Figure 42 – IEC 60721-3-2 (1997) – Shock severity . 47
Figure 43 – IEC 60721-4-2 (1997) – Shock severity . 47
Figure 44 – IEC 60721-4 (1997)– Recommended repeated shock severity . 48

– 4 – TR 62131-3  IEC:2011(E)
Table 1 – British Rail measurements summary of vibration measurements . 23
Table 2 – Association of American Railroads intermodal study as it relates to Figure 11 . 28
Table 3 – Association of American Railroads – Intermodal study as it relates to Figure 12. 29
Table 4 – Association of American Railroads – Intermodal study as it relates to Figure 13. 30
Table 5 – Association of American Railroads intermodal study – summary of results
from shock measurements . 31
Table 6 – Association of American Railroads intermodal study– summary of results from
vibration measurements . 31
Table 7 – Association of American Railroads – Boxcar measurements – distribution of
shocks . 37
Table 8 – Association of American Railroads – Railroader measurements as they
related to Figure 25 . 38

TR 62131-3  IEC:2011(E) – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ENVIRONMENTAL CONDITIONS –
VIBRATION AND SHOCK OF ELECTROTECHNICAL EQUIPMENT –

Part 3: Equipment transported in rail vehicles

FOREWORD
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The main task of IEC technical committees is to prepare International Standards. However, a
technical committee may propose the publication of a technical report when it has collected
data of a different kind from that which is normally published as an International Standard, for
example "state of the art".
IEC/TR 62131-3, which is a technical report, has been prepared by IEC technical committee
104: Environmental conditions, classification and methods of test.

– 6 – TR 62131-3  IEC:2011(E)
The text of this technical report is based on the following documents:
Enquiry draft Report on voting
104/508/DTR 104/537/RVC
Full information on the voting for the approval of this technical report can be found in the report
on voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2. A list of all
the parts in the IEC 62131 series, under the general title Environmental conditions – Vibration
and shock of electrotechnical equipment, can be found on the IEC website.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of this publication will remain unchanged until the
stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data related to
the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this standard may be issued at a later date.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this document using a colour printer.

TR 62131-3  IEC:2011(E) – 7 –
ENVIRONMENTAL CONDITIONS –
VIBRATION AND SHOCK OF ELECTROTECHNICAL EQUIPMENT –

Part 3: Equipment transported in rail vehicles

1 Scope
IEC/TR 62131-3, which is a technical report, reviews the available dynamic data relating to
electrotechnical equipment transported by rail vehicles. The intent is that from all the available
data an environmental description will be generated and compared to that set out in IEC 60721.
For each of the sources identified the quality of the data is reviewed and checked for self
consistency. The process used to undertake this check of data quality and that used to
intrinsically categorize the various data sources is set out in IEC/TR 62131-1.
This technical report primarily addresses data extracted from a number of different sources for
which reasonable confidence exist as to their quality and validity. The assessment also
presents data for which the quality and validity cannot realistically be reviewed. These data are
included to facilitate validation of information from other sources. The report clearly indicates
when it utilizes information in this latter category.
This technical report addresses vibration and shock data from three different measurement
exercises, i.e. one on the UK rail system and two on the USA rail system. Although one of
these relates to a multimodal system in limited use world wide, data from it are included to
facilitate validation of information from other sources. The vast majority of the rail
measurements reviewed are from the USA and the remainder from Western Europe. Some of
the data sources considered indicate the inclusion of some quite old vehicles. It has not been
possible to identify the rail data considered in setting the existing IEC 60721 severities.
Although the majority of the measurement exercises considered in this technical report
supplied both vibration and shock information, a number of measurement exercises are biased
towards the shock conditions of rail transportation. The severity and incidence of shocks is
mostly related to the occurrence shunting of individual wagons. The occurrence of shunting of
individual wagons is in turn dependant upon the operational strategy adopted by the national
rail systems. A significant number of rail systems no longer adopt methods of operation which
assemble train sets when the wagons are carrying sophisticated goods (carriage of bulky raw
minerals is a common exception). Other rail systems purposely utilize good quality wagons
and/or procedures of operation to significantly mitigate shunting loads. These strategies are
intended to minimize shock severities for sensitive equipment such as electrotechnical
equipment.
Relatively little of the data reviewed have been available in electronic form. To permit
comparison a quantity of the original (non-electronic) data have been manually digitized in this
techical report.
2 Normative references
The following referenced documents are indispensable for the application of this document. For
dated references, only the edition cited applies. For undated references, the latest edition of
the referenced document (including any amendments) applies.
IEC 60068-2 (all parts), Environmental testing – Part 2: Tests
IEC 60721 (all parts), Classification of environmental conditions

– 8 – TR 62131-3  IEC:2011(E)
IEC 60721-3 (all parts), Classification of environmental conditions – Part 3: Classification of
groups of environmental parameters and their severities
IEC 60721-3-2:1997, Classification of environmental conditions – Part 3: Classification of
groups of environmental parameters and their severities – Section 2: Transportation
IEC/TR 60721-4-2, Classification of environmental conditions – Part 4-2: Guidance for the
correlation and transformation of environmental condition classes of IEC 60721-3 to the
environmental tests of IEC 60068 – Transportation
3 Data source and quality
3.1 UK rail measurements
The vibration data in [1] from the UK rail system are relatively old (1980) and were
commissioned by the UK MOD to summarize existing knowledge of the shock and vibration
environments experienced by goods exposed to UK rail transit. The report initially sets out the
five methods of operation used at that time within the UK. However, several of these are no
longer adopted.
The report indicates that the major factors creating vibration environment within a vehicle are
as follows:
– vehicle running gear characteristics (suspension, wheelbase, etc.);
– track condition;
– vehicle speed;
– vehicle lading condition.
This techical report contains vibration information indicated as from “worst case” vehicles (two
axle, short wheelbase, simple-suspension), intermediate suspension vehicles (longer
wheelbase) and advanced suspension vehicles (long wheelbase, bogie good suspension and
air brakes). The data are relatively low frequency (less than 100 Hz) but beyond the low pass
filter frequency (10 Hz to 20 Hz – the report is not specific as to the actual roll-off frequency).
The report admits that higher frequency content does exist but has no general information.
Although it does indicate that with a rail sleeper spacing of approximately 0,7 m, a vertical
component between 20 Hz and 40 Hz would be expected for speeds of 50 km/h to 100 km/h.
The report does not supply any information as to the statistical errors on the measured data
including the duration of measurements. Nor are any specific information supplied as to the
exact location of the transducers or the specific vehicles used.
The report indicates that shocks, particularly longitudinally, can occur between two vehicles
during running as a consequence of vehicle-to-vehicle interaction arising from traction, braking
and gradient effects. The severity of such shocks is generally determined by the vehicle
coupling arrangement and braking condition. Vehicles may be equipped with vacuum brakes,
air brakes or none at all. Coupling between wagons may allow longitudinal movement (loose
coupled) or none at all (tight coupled).
The report indicates that major shocks are attributed to heavy impact shunting in marshalling
yards. The shocks severity is dependant upon impact speed, buffering gear characteristics and
total mass of the wagon. The report explains two types of buffer are used: spring and hydraulic.
The older spring buffers limit longitudinal accelerations until the springs close solid, typically at
an impact speed of approximate 8 km/h, after which the acceleration levels rise rapidly. As the
springs are linear energy storage systems, when the stored energy is released it can cause
“shuttling” of the vehicles. As springs are linear, the impact shock is approximate to a classic
half sine. Hydraulic buffers are fitted to newer wagons and are specifically intended to mitigate
___________
References in square brackets refer to the bibliography.

TR 62131-3  IEC:2011(E) – 9 –
impact shock. They are designed to give a more constant retardation over the entire impact
speed range which is usually far greater than for spring systems. The amount of energy
released into “shuttling” is also significantly reduced. The impact shock characteristics
approximate to a trapezoidal pulse. The report sets out a distribution of actual shunting impact
velocities (reproduced in Figure 3).
Overall, the data in the report cannot be considered adequate to meet the required criteria for
data quality (single data item). This is largely because the source and statistical quality of the
data cannot be established. The report is included, nevertheless, mostly because it sets out a
good background to the source and influences on both the rail shock and vibration
environment.
3.2 Association of American Railroads – Lengthways shocks
This relatively recent (1995) document (see [2]) from the Association of American Railroads is
on the measurement and analysis of lengthwise rail shocks. Although the title of the document
infers a description of a measurement and analysis exercise, in reality the majority of the report
comprises a general background discussion. As a consequence, it is not a straightforward
exercise to determine whether the data source meets the required criteria. The data source
relates entirely to shunting shocks on the US system. The report contains tabulated longitudinal
shock information relating to impacts between
– standard draft gear cars into standard draft gear cars at velocities of 1,8 m/s – 2,7 m/s
(4 mph to 6 mph),
– M921 cushioned cars into standard draft gear cars at velocities of 1,8 m/s – 3,8 m/s (4 mph
to 8,6 mph),
– M921D cushioned cars into standard draft gear cars at velocities of 1,8 m/s – 3,6 m/s
(4 mph to 8 mph) ,
– M921 cushioned cars into M921 cushioned cars at velocities of 1,8 m/s – 3,6 m/s (4 mph to
8 mph) ,
– M921D cushioned cars into M921 cushioned cars at velocities of 1,8 m/s – 3,7 m/s (4 mph
to 8,4 mph) ,
– M921D cushioned cars into M921D cushioned cars at velocities of 1,8 m/s – 3,7 m/s
(4 mph to 8,4 mph) ,
– cushioned cars into cushioned cars (type unknown) at velocities of 1,3 m/s – 4,0 m/s
(3 mph to 9,0 mph).
The document indicates that the standard draft gear cars are spring buffered with around 85
mm of buffer travel and little damping. The cushioned cars are hydraulic buffered with between
250 mm and 500 mm of buffer travel. The measurements were made at a sample rate of 256
samples per second (sps) and with an anti-aliasing filter set at 60 Hz. For each impact a record
of duration 2 s was acquired (although none of the shocks appeared to utilise that record
window). It is implied that the measurements were made with only a single tri-axial transducer
probably embedded within an EDR-3 digital recorder. The actual location of the transducers /
EDR-3 is not indicated. Rail impact velocities were acquired using a radar gun (accuracy
unstated). The integral EDR-3 transducer is usually piezo-resistive and able to resolve to DC.
As such would be a good choice for the measurement of long duration pulses under
consideration by this work.
The report presents peak positive acceleration, peak negative acceleration, r.m.s. and crest
factor for 60 Hz filtered data, for 10 Hz filtered data and 3 Hz filtered data. Based upon the
10 Hz and 3 Hz filtered data the shock duration and velocity change are derived. The latter is
compared with measured car impact velocity. A considerable proportion of the report is
expended in establishing this velocity comparison.
The data in the report is specifically related to the shunting shock conditions. It cannot be
considered adequate to meet the required validated criteria for data quality (single data item).
This is largely because the source and statistical quality of the data cannot be established.
However, the information has a degree of traceability and realistically is the best available.

– 10 – TR 62131-3  IEC:2011(E)
3.3 Association of American Railroads – Intermodal environment
This relatively recent (1991) work from the Association of American Railroads (see [3])
concerns the measurement and analysis of vibration and shock conditions experienced by
standard ISO containers when transported by both rail and road. The objective was clearly to
establish the relationship between the vibration and shock conditions experienced during rail
and road movements. The technical summary provides a description of a measurement and
analysis exercise and presents some of the results. Whilst establishing the validity of the data
and quality of the exercise from the technical summary alone is not straightforward, the source
is supported by separate technical reports for each of the phases (see [4], [5] and [6]). Further,
an “executive summary” report is also available (see [4]), some of which is reproduced below.
The data source relates almost entirely to ISO containers on the US and Canadian rail system.
The study was divided into three phases:
• Phase One: A standard 27 m (89 foot) trailer on flat car (TOFC) was loaded with two
trailers and moved in excess of 14 500 km (9 000 miles) over mountains, rolling hills and
level terrain on U.S. and Canadian transcontinental routes.
• Phase Two: Four loaded, standard 12 m (40 foot) ISO containers were moved in dedicated
intermodal trains over more than 18 000 km (10 900 miles) in principal U.S. rail corridors.
The test containers were moved in double-stack rail cars, on articulated container on flat
car (COFC) cars and articulated TOFC cars. Articulation is a way of joining rail cars to
eliminate slack motion between them.
• Phase three: A 14 m (45 foot) intermodal trailer travelled more than 4 200 km (2 600
miles) of interstate highways, 1 900 (3 050 km) miles of primary (non-interstate) highways
and 2 253 km (1 400 miles) of urban streets. Data was also collected for lift-on/lift-off
operations at several intermodal ramps.
The report indicates differing data recording systems were used in the different phases. For
phase 1 both an 18 channel data acquisition system was used as well as six self contained
data recorders. Two data recorders were installed on each test trailer and container. The multi-
channel system sampled at 128 sps with a filter at 30 Hz. The total record duration was around
11 % of a total of 4 200 km (2 600 miles) of rail transport. The six self contained units
measured mostly shocks and adopted a sample rate of 1 600 Hz into 0,5 s files. The remaining
two phases utilized two self contained recorders. One recorder was programmed to record
random vibration data at preset intervals with a threshold of 0,1 g. The other recorder was set
to record only acceleration levels exceeding a preset 0,5 g threshold, providing shock data for
each test vehicle. The two pre-programmable data recorders, housed longitudinal, lateral and
vertical accelerometers capable of DC measurement (piezoresistive). The sample rate was
250 sps in both cases.
The information in this report is limited to large 12 m (40 foot) ISO containers and the
US/Canadian rail systems. However, the quality of the information is good and meets the
required validation criteria for data quality (single data item).
3.4 Association of American Railroads – Study of the shock and vibration environment
in boxcars
This relatively recent (1992) work from the Association of American Railroads (see [8]) is on
the measurement and analysis of vibration and shock conditions experienced in both standard
and cushioned boxcars. A lot of commonality exists between this study and that reported
above. Data were recorded on some 16 journeys covering nearly 40 000 km (25 000 miles) and
encompassed 14 different boxcars. The instrumented boxcars had a range of payloads and
were located at different positions within the train set. Each boxcar had between 2 and 4 pre-
programmed data recorders each with a single integral triaxial piezoresistive accelerometer.
One recorder was programmed to record 4 s of random vibration data at preset intervals with a
threshold of 0,1 g. The other recorder was set to record 2 s of data but only when acceleration
levels exceeded a preset 0,5 g threshold for 15,6 ms, providing shock data for each test
vehicle. In both cases the recorder sample rate was 256 sps. One pair of recorders was
positioned as close to the centre of the payload bay floor as possible.

TR 62131-3  IEC:2011(E) – 11 –
The study report, as was the case also in the previous study, presents amplitude probabilities
for the shock data and PSD data for the vibration data.
The information in this report is limited to boxcars on the US rail system. However, the quality
of the information is good and meets the required validation criteria for data quality (single data
item).
3.5 Association of American Railroads – Study of the railroad shock and vibration
environment for railroader equipment
This relatively recent (1992) work from the Association of American Railroads (see [9]) is on
the measurement and analysis of vibration and shock conditions experienced by trailers carried
on Mk IV and Mk V railroader equipment. A lot of commonality exists between this study and
the two previous studies. Data was recorded on two different routes encompassing two types of
railroader equipment. Eight different payloads were utilised four for each type of railroader
equipment, however, these were not identical in the two cases. Each instrumented trailer had 2
pre-programmed data recorders, each with a single integral triaxial piezoresistive
accelerometer. One recorder was programmed to record 4 s of random vibration data at preset
intervals with a threshold of 0,1 g. The other recorder was set to record 2 s of data but only
when acceleration levels exceeded a preset 0,5 g threshold for 15,6 ms, providing shock data
for each test vehicle. In both cases the recorder sample rate was 256 sps. One pair of
recorders was positioned as close to the (presumably rear) door threshold laterally centred on
the payload bay floor.
The study report, as was the case also in the previous study, presents amplitude probabilities
for the shock data and PSD data for the vibration data.
The information in this report is limited to a particular type of equipment which allows road
vehicles to be moved by rail on the US rail system. Again the quality of the information is good
and meets the required validation criteria for data quality (single data item).
3.6 Supplementary data
The data collection exercise which preceded this assessment also identified relevant sets of
information which come from reputable sources but for which the data quality could not be
adequately verified. Although, they are included here to facilitate validation of data from other
sources, care should be taken when utilizing information in this category.
Johnson. In the mid 1970’s G.E. Johnson of Cambridge Consultants in the UK was funded by
the UK MOD to review the transportation shock environment. The final report of this work (see
[10]) was delivered in 1976 and includes a significant review of available rail shock data. The
shocks reported were all from inter-wagon impacts during shunting. The report includes a
number of references containing rail shunting shock data. However, these are all pre-1970 and
many relate to unobtainable data sources (hence are not reproduced here). Further the
information set out by Johnson on shutting practice (Figure 28) are not representative of the
practice used on the UK rail system in recent years.
Various US rail vehicles circa 1970. As part of an exercise, in the early 1970’s, to
authenticate test severities for the US military specification Mil Std 810, J.T. Foley (see [11]) at
Sandia National Laboratories in the US undertook an extensive exercise to establish
transportation severities on a number of platforms including several rail vehicles. As far as can
be determined the vehicles used real US rail roads and conditions. The vibration information
included data from 3 journeys and “other” (source unknown) published data. A total of 22
events were summarized up to 350 Hz. Whilst several measurements were considered, the
process adopted does not allow information from individual vehicles to be identified. Moreover,
the analysis process Foley used throughout his work is relatively unique and not immediately
compatible with other information presented in this assessment.
Wagon GDE capacité. Information is contained within the French military specification
GAM EG 13 (see [12]) from three different vehicles. The measurements were made on a

– 12 – TR 62131-3  IEC:2011(E)
variety of real rail conditions and speeds (although the exact nature is not known). All the data
are presented in the form of PSD’s of 1 Hz (or better) frequency resolution. The duration of the
records used for the analysis is unknown and hence the analysis random error cannot be
determined. Overlaid vibration spectra for the one vehicle are presented for vehicle speeds of
90 km/h, 100/h km and 120 km/h, respectively. Additionally shock response spectra for impacts
at 4 km/h and 7 km/h are presented.
Miscellaneous data. During the course of the data search a number of possible data sources
were identified for which the data were not traceable to any reasonable extent. These are
included here for completeness because they may help support information from more
traceable sources. Most of these sources are courtesy of Dr Ulrich Braunmiller and the EC
sponsored SRETS work. Vertical responses from two rail vehicles presented in ASTM D4728-
91 (see [13]). However, these data may well be those of the Association of American Railroads
– Intermodal environment. The SRETS work also documents data from the UK Defence
Standard Def Stan 00-35; which are based upon the UK Rail measurements already
documented.
4 Intra data source comparison
4.1 General remark
The purpose of the following paragraphs is to review each data source for self consistency.
The process for evaluating the vibration data takes into account the variation of vibration due to
operational usage and aircraft characteristics. The level of confidence resulting from this
review directly influences the levels of factoring and enveloping that are used when deriving
environmental severities.
4.2 UK Rail measurements
The report from the UK rail system (see [1]) makes a number of comparisons but does not set
out the basis for these. With regard to vibration the report suggests that vertical vibrations are
marginally more severe than lateral, whilst longitudinal vibrations are usually insignificant.
However, the report does indicate this vehicle possesses simple suspension, which is a lot
worse in the vertical axis (these simple vehicles are essentially all used for transportation of
minerals). The report contains limited vibration information which are shown in Figures 1 and 2
and relate to vehicle vertical and lateral axes. Summary amplitude information are summarized
in Table 1.
The report indicates that longitudinal shocks can occur between two vehicles during running as
a consequence of vehicle to vehicle interaction arising from traction, braking and gradient
effects. The severity of such shocks is generally determined by the vehicle coupling
arrangement and braking condition. Vehicles may be equipped with vacuum brakes, air brakes
or none at all. Coupling between wagons may allow longitudinal movement (loose coupled) or
none at all (tight coupled). Typical maximum longitudinal shocks are given as
– tight coupled, fully braked 0,2 g,
– loose coupled, fully braked 0,5 g,
– loose coupled, unbraked 2,0 g.
The report indicates that major shocks are attributed to heavy impact shunting in marshalling
yards. The shock’s severity is dependant upon impact speed, buffering gear characteristics and
total mass of wagon. The report explains two types of buffer are used spring and hydraulic. The
report indicates the longitudinal shock has the longest duration but not necessarily the greatest
amplitude. Due to the position of the wagon centre of gravity (c of g) above the buffer height
vertical shocks may be typically one and a half times greater in acceleration amplitude than
longitudinal shocks but with a duration of only 10 ms. The severity of lateral shocks is more
variable but can have the same greater acceleration amplitude as longitudinal shocks but with
a duration of only 20 ms. Typical maximum longitudinal acceleration values are given as

TR 62131-3  IEC:2011(E) – 13 –
– spring buffers, fully laden wagon = 1,5 g,
until buffers fully compressed
– spring buffers, lightly laden wagon = 3,0 g,
until buffers fully compressed
– spring buffers, fully laden wagon = >15,0 g,
after buffers fully compressed
= 2,
...