Testing concept and in-service testing

Freight wagon selection and wagon configuration

Four wagon groups, each with three freight wagons of the same wagon type, will be provided for testing the DAC prototypes. Each wagon group consists of a four-axle open bulk goods wagon (Eanos x-059), a two-axle sliding wall wagon (Hbbins 306) and a four-axle gas tank wagon (Zags 119). The aim of this wagon configuration is to test the couplings on freight wagons that are frequently used in European freight traffic and can therefore be considered representative.

A total of 687,495 freight wagons are registered in the European Vehicle Register ECVVR. The second largest wagon category with a total of 114,669 vehicles is the group of open freight wagons “E”, which also includes the selected four-axle Eanos.

The selected Zags tanker belongs to the third largest wagon category in Europe (“Z”) with a total of 109,728 vehicles. With a length over the buffer of 18.8 m, the Zags is the longest of the three selected freight wagon types. The use of freight wagons of different lengths for the tests is critical for testing automatic coupling in narrow track curves, among other things. The large overhang on this wagon is a particular challenge here.

In order to test the behaviour of light two-axle freight wagons when using a DAC in addition to four-axle freight wagons, a Hbbins type closed sliding wall wagon was selected as the third wagon category. A total of 45,345 “H” type freight wagons are in use throughout Europe. This means that in total, the three selected freight wagon types represent 269,742 freight wagons in Europe. As well as this, the selection laid out above means that the test results can be transferred to other two-axle and four-axle freight wagons with comparable dimensions.

All wagons are equipped with LL or K soles for the brakes, meaning they will comply with the legal requirements according to TSI Noise.

1See Liebing, S. (2018), Quantification of the need to retrofit freight wagon fleets in Germany and member states of the European Union in light of the differing legal frameworks, TÜV Rheinland InterTraffic GmbH on behalf of the Eisenbahn-Bundesamt (Federal Railway Authority), Berlin, 2018.

Details of the wagons used

“Hbbins 306” sliding wall wagon
Empty approx. 14.9 t, full approx. 44.9 t
Length over buffer: 15.5 m
Distance between pivots: 9 m

Source: DB AG

Technical drawing; Source: DB Cargo AG

“Eanos-x 059” bulk goods wagon
Empty approx. 24 t, full approx. 90 t
Length over buffer: 15.74 m
Distance between pivots: 10.7 m

Source: DB AG

Technical drawing; Source: DB Cargo AG

“Zags 119” gas tank wagon
Empty approx. 32.5 t, full approx. 90 t
Length over buffer: 18.8 m
Distance between pivots: 12.1 m

Source: GATX

Technical drawing; Source: GATX

Configuration of the demonstrator

In each of the four groups of wagons, the two inner coupling points will be equipped with digital automatic couplings. Four manufacturers have participated in carrying out the tests by providing prototypes: CAF (SA3 type), Dellner (Scharfenberg type), Wabtec (Schwab type) and Voith (Scharfenberg type).

The outer wagons in each case, the Zags and Eanos wagons, are equipped with the standard equipment (screw coupling and buffers) on one side. This allows the four groups of wagons to be connected to form a block train, regardless of the coupling capability of the DAC coupling systems with each other.

In order to be able to simulate different loading conditions in the test sequence, the Zags wagons are loaded with water, the Hbbins wagons with steel mesh boxes and the Eanos wagons with concrete items.

Configuration of the demonstrator


Preparing the freight wagons

for electrical and technical measuring equipment

Additional extensions are necessary in order to be able to equip the wagons with measuring technology for test runs. Since some of the couplings are still in the prototype stage, a concept including three separate connection boxes was designed. This makes it possible to work with consistent interfaces. The concept described below serves as a support for the measuring technology for the duration of the test. The concept is not part of a solution that will be used later when the freight wagons are retrofitted.

The “central connection box” for the power supply and data communication houses all the measuring equipment during the test and is connected to the “coupling connection boxes” via a central cable that is the same for all wagons.

A compact “coupling connection box” is fitted in the area of each coupling. This allows the manufacturers’ cable concepts, which are not yet standardised, to be wired consistently and communicate to the wagon via a main line.

As well as this, the coupling can be shunted at the coupling connection box with a plug connection on the DAC side in the event of a fault and the four wagon groups can be connected on the screw coupling side. In regular test runs, the electric coupler takes over this function in the DAC area and connects the power and data lines of the coupled wagons.
Central connection box

Central connection box (With fitted weather covers)

Central connection box (Without fitted weather covers)

Coupling connection box

The pictures show the two boxes using an Eanos-x-509 wagon as an example.

Technical measuring equipment

For the tests in phase I, measuring technology is deployed on the freight wagons, which can be divided into three groups:

  Measuring technology necessary for mechanical and pneumatic testing

2   Measuring technology that proves the functionality of the energy supply

3   Measuring technology for proving reliable data communication

These three groups are described in more detail below.

Mechanical and pneumatic measuring technology

The physical measured variables that are recorded during the tests and the sensor types used for each are listed below.

Measured variables Sensor Components Vehicle Exact position
Coupling force Strain gauge (SG) Push/pull rod Hbbins 306 Both couplings
Acceleration coupling
(Mechanical part)
Accelerometer
(3-axis)
Coupling head Hbbins 306 Both couplings
Acceleration coupling
(Electrical part)
Accelerometer
(3-axis)
E-coupling Hbbins 306 Both couplings
Wagon speed Radar sensor Wagon On rolling wagon per coupling test Underneath the vehicle
Driving distance of the wagon Radar sensor Wagon On rolling wagon per coupling test Underneath the vehicle
Main air line pressure Pressure sensor Wagon Using a coupling point as an example On the control valve
Brake cylinder pressure Pressure sensor Wagon Using a coupling point as an example On the control valve
Position of the driver’s brake valve Draw-wire encoder Driver’s cab Traction unit Control lever for the driver’s brake valve

Two measuring coupling heads are provided for each of the four coupling types. This means a total of eight coupling heads are instrumented with strain gauges (SG) and calibrated for force. The strain gauges are full bridge circuits.

According to physical principles, the force in both coupling heads is the same (F1 = F2), so it’s sufficient to determine the force in only one of the two heads. The figure on the right shows a schematic diagram of a DAC, with the measuring point where the strain gauges are applied, marked in pink.

Strain gauge

Components for testing
the power supply and data communication

The components for testing the power supply and data communication are listed in the table below. These are integrated into the central connection box.

Module Description
Industrial PC The embedded PC is the central element for controlling the communication systems. Integrating all systems is achieved through communication system-dependent software modules. The embedded PC contains software for testing and analysing the communication links. This component also controls the tests.
CAN communication module
The (2-port) CAN FD communication module converts the CAN data packets to Ethernet.
Powerline module For testing the Powerline system
WiFi access point/
client For testing the radio system as a communication link between the wagons, a WiFi access point is used, which can also be set to client mode.
Relay An industrial relay is used to bridge the CAN connection. This allows the CAN bus to be operated in segmented communication system mode as well as in continuous line mode.
Ethernet switch The Ethernet switch bundles the various communication systems for connection to the Ethernet port of the industrial PC. If necessary, an adapter for modules from parallel projects can also be connected here.
I/O module I/O modules are used for the following functions:

  • Switching the relay (CAN bus)
  • If applicable, 4.20mA module for sensors for voltage monitoring of the 110V DC line
Other Installation material for setting up the wagon box
Power management battery Battery head station: The module automatically charges the battery when powered by the 110V DC line. If the power supply fails, the battery is automatically switched on to provide power. If necessary, you can query the battery’s state of charge (feed-in/discharge power).
Battery Battery for connection to the power management
Power supply unit (110V DC to 24V DC)
Conversion of the voltage on the 110V DC supply of the train bus to the internal wagon voltage level of 24V DC
Signal lamp
Display visible outside the wagon box to show conditions of the wagon (voltage present on 110V DC line, coupling condition if information is available)

Description of test concept

In phase I, the procured couplings are tested with a carefully designed test scenario. The wagon configuration described at the beginning and the technical measuring equipment are applied.

Phase I was started in September 2020 after the demonstrator was installed (June to September 2020). However, due to unresolved technical questions regarding the coupling prototypes, the test programme could not be finalised by February 2021 as planned. Phase I was therefore extended until 30/06/2021 in close cooperation with all coupling manufacturers.

Loading conditions

Testing the couplings makes it necessary to individually change the loading condition of the wagons. The number of variations should be kept as small as possible and yet all extreme conditions for the couplings should be represented. On the one hand, the loading condition influences the vertical height offset; on the other hand, the forces acting on the couplings change.

Two scenarios were identified for testing the couplings, the extreme cases of which will be investigated. On the one hand, the mechanical load capacity of the couplings, i.e. testing the behaviour of the coupling when large forces are applied. On the other hand, the possible grab range in which the couplings can be coupled and travel through different track geometries without restrictions. The grab range can be divided into a horizontal and a vertical grab range.

The Zags wagon with a length over buffer of 18.8 m and a pivot spacing of 12.1 m generates the largest horizontal deflections of the coupling. The Hbbins wagon, on the other hand, shows the greatest change in buffer height when comparing the states “charged” to “empty”. This means the coupling process between the loaded Hbbins wagon and the empty Zags wagon is the biggest challenge for testing the grab range.

When examining the extreme case for mechanical load capacity, the most relevant case is a full Hbbins wagon coupled to a heavy Eanos wagon. The maximum load of the Eanos wagon is 8 t greater than that of the Zags wagon, which has a higher empty weight with the same maximum weight. The greatest difference at the same maximum value should therefore occur in the test between the loaded Hbbins and the loaded Eanos wagon.

The tests carried out at high speeds are expected to produce the greatest forces introduced into the carriage frame. In order to slowly approach the maximum values, the Hbbins wagon is initially only half ballasted. In all other tests, partial loading does not provide any additional findings.

Test descriptions

The tests are partly carried out in parallel during the coupling processes in the different track geometries and at different speeds. Some of the tests described are carried out when the vehicle is stationary.

The mechanical tests are divided into coupling tests, operational tests (passing through geometries) and tests to investigate shear forces and derailment safety.

The tests for the test concept are divided into:

Mechanical tests
Coupling and driving tests
Shear force tests
Electrical tests
Tests for data communication
Climatic chamber tests

Coupling and driving tests

The mechanical tests include coupling tests and operational tests (passing through geometries). Carrying out a large number of tests at different speeds in different geometries is necessary to prove the coupling capability and unrestricted operation. To better assess the significance of a result and its repeatability, the tests must be repeated several times. Each test is therefore carried out five times.

Loading condition 1
Spec. no. Infrastructure Eanos Hbbins Zagns 2 km/h 4 km/h 6 km/h 8 km/h 10 km/h 12 km/h Drive No. of
driving tests
3.1 Straight track Fully loaded Empty Empty 5 5 5 5 5 5
3.2 190 m track curve Fully loaded Empty Empty 5 5 5 5
4.1 190 m track curve Fully loaded Empty Empty Pulled 5
4.2 190 m track curve Fully loaded Empty Empty Pushed 5
3.3 150 m track curve Fully loaded Empty Empty 5 5 5 5
4.3 150 m track curve Fully loaded Empty Empty Pulled 5
4.4 150 m track curve Fully loaded Empty Empty Pushed 5
3.4 190 m S track curve Fully loaded Empty Empty 5 5
4.5 190 m S track curve Fully loaded Empty Empty Pulled 5
4.6 190 m S track curve Fully loaded Empty Empty Pushed 5
3.6 150 m S track curve
with 6 m intermediate straight
Fully loaded Empty Empty 5 5
4.9 150 m S track curve
with 6 m intermediate straight
Fully loaded Empty Empty Pulled 5
4.10 150 m S track curve
with 6 m intermediate straight
Fully loaded Empty Empty Pushed 5
4.11 100 m track curve Fully loaded Empty Empty Pulled 5
4.12 100 m track curve Fully loaded Empty Empty Pushed 5
4.13 75 m track curve Fully loaded Empty Empty Pulled 5
4.13 75 m track curve Fully loaded Empty Empty Pushed 5
4.14 Ramp with 2°30′ incline Fully loaded Empty Empty Pulled 5
4.15 Ramp with 2°30′ incline Fully loaded Empty Empty Pushed 5

The coupling point to be evaluated in coupling tests is located between the wagons marked in pink

Driving tests with a coupled three-wagon group are highlighted in blue

The overview in the table above shows the tests in loading condition 1. Here the fields with black text contain coupling tests and the fields with blue text contain the tests in which geometries are passed through in the coupled state (pulled and pushed).

Loading condition 1 tests the empty wagons. The focus here is on the coupling capability between the Zags and the Hbbins wagon.

As explained, loading condition 2 in the table below serves as an intermediate step, so that only tests on the straight track are carried out here. Here, too, the speed is increased up to a maximum of 12 km/h, as in loading condition 1.

Loading condition 2
Spec. no. Infrastructure Eanos Hbbins Zagns 2 km/h 4 km/h 6 km/h 8 km/h 10 km/h 12 km/h Drive No. of driving tests
3.1 Straight track Loaded Partially loaded Empty 5 5 5 5 5 5

The coupling point to be evaluated in coupling tests is located between the wagons marked in pink

Driving tests with a coupled three-wagon group are highlighted in blue

Loading condition 3
Spec. no. Infrastructure Eanos Hbbins Zagns 2 km/h 4 km/h 6 km/h 8 km/h 10 km/h 12 km/h Drive No. of
driving tests
3.1 Straight track Fully loaded Fully loaded Empty 5 5 5 5 5 5
3.2 Straight track Fully loaded Fully loaded Empty 5 5 5 5 5 5
3.2 190 m track curve Fully loaded Fully loaded Empty 5 5 5 5
3.3 191 m track curve Fully loaded Fully loaded Empty 5 5 5 5
4.1 190 m track curve Fully loaded Fully loaded Empty Pulled 5
4.2 190 m track curve Fully loaded Fully loaded Empty Pushed 5
3.3 150 m track curve Fully loaded Fully loaded Empty 5 5 5 5
3.4 151 m track curve Fully loaded Fully loaded Empty 5 5 5 5
4.3 150 m track curve Fully loaded Fully loaded Empty Pulled 5
4.4 150 m track curve Fully loaded Fully loaded Empty Pushed 5
3.4 190 m S track curve Fully loaded Fully loaded Empty 5 5
3.5 191 m S track curve Fully loaded Fully loaded Empty 5 5
4.5 190 m S track curve Fully loaded Fully loaded Empty Pulled 5
4.6 190 m S track curve Fully loaded Fully loaded Empty Pushed 5
3.6 150 m S track curve
with 6 m intermediate straight
Fully loaded Fully loaded Empty 5 5
3.7 151 m S track curve
with 6 m intermediate straight
Fully loaded Fully loaded Empty 5 5
4.9 150 m S track curve
with 6 m intermediate straight
Fully loaded Fully loaded Empty Pulled 5
4.10 150 m S track curve
with 6 m intermediate straight
Fully loaded Fully loaded Empty Pushed 5
4.11 100 m track curve Fully loaded Fully loaded Empty Pulled 5
4.12 100 m track curve Fully loaded Fully loaded Empty Pushed 5
4.13 75 m track curve Fully loaded Fully loaded Empty gezogen 5
4.13 75 m track curve Fully loaded Fully loaded Empty geschoben 5
4.14 Ramp with 2°30′ incline Fully loaded Fully loaded Empty gezogen 5
4.15 Ramp with 2°30′ incline Fully loaded Fully loaded Empty geschoben 5

The coupling point to be evaluated in coupling tests is located between the wagons marked in pink

Driving tests with a coupled three-wagon group are highlighted in blue

Loading condition 3 is used to test two aspects. On the one hand, the combination of the loaded Eanos and the loaded Hbbins wagon transfers the greatest forces via the coupling. Secondly, the combination of the loaded Hbbins wagon and the empty Zags wagon has the largest vertical difference in height of the couplings, coupled with the largest horizontal difference due to the geometry of the Zags wagon.

The choice of these combinations covers all extreme cases. All other combinations fall between these extreme cases and do not yield any further findings.

Shear force tests

In addition to the coupling and driving tests, the mechanical tests also include tests to test the shear forces and derailment safety. For testing the resulting shear forces and the bearable longitudinal compressive forces of the coupling designs, longitudinal compressive forces are specifically applied. The basis for the tests are the specifications according to UIC Code 530-2.

The tests are carried out on the 150 m S track curve with 6 m intermediate straight (similar to Spec. 4.10). The track geometry for the test is shown in the figure to the right.

Representation of test geometry
The test track consists of an s-shaped track curve with R = 150 m with an intermediate straight of 6 m length. The test track is not excessively elevated. The average track gauge is 1450 – 1465 mm.
Source: UIC Merkblatt 530-2, Güterwagen – Fahrsicherheit, 7. Ausgabe, December 2011

Representation of the structure of the test train
Source: UIC Merkblatt 530-2, Güterwagen – Fahrsicherheit, 7. Ausgabe, December 2011

The Hbbins wagon in the middle of the three-wagon configuration is tested specifically. We know that two-axle wagons are the most prone to derailment in such tests. The neighbouring Eanos and Zags wagons are fully charged. The test is run by pushing, with brake wagons coupled in front of the wagons to allow the test forces to be applied by the locomotives coupled at the rear. This structure is outlined in the figure to the left.

Taking measurements during tests
During the test, at least the following measured variables shall be recorded while going through the test track:

  • Longitudinal compressive force FLxi
  • Wheel lifts dzij on all wheels
  • Wheel set bearing shear forces Hyj on all wheel sets
  • Distortion of the wheel set holders dyAij1 on all wheels
  • Registering the track marks
  • Path (e.g. 1 m mark)

Measured variables during the shear force tests according to UIC 530-2
Note: The buffer lateral shifts have not been measured in the DAC4EU tests. The buffers are disassembled.
Source: UIC Merkblatt 530-2, Güterwagen – Fahrsicherheit, 7. Ausgabe, December 2011

In accordance with the specifications of the UIC Code and in order to identify the limits of the couplings, the longitudinal force, starting at 100 kN, is successively increased in 100 kN steps. The variables mentioned on the left are measured. The buffer lateral displacement that’s measured in tests with screw couplings is not applicable in tests with DAC.

On top of the proof of derailment safety, this means that an evaluation of the couplings can also be carried out. For example, it’s possible to specifically examine which design generates the smallest lateral forces and therefore causes the least wear and tear. In addition, it allows high bearable longitudinal compressive forces as well as longer and/or heavier trains with the brake lever position “P” to be able to run more efficiently on the rail network.

Electrical tests

The tests for examining the electrical couplings:

No. Name of test
E11 Measuring the contact resistance of the electrical contacts
E12 Measuring the insulation resistance of the e-coupling
E13 Measuring the duration of establishing contact during the coupling process
E14 Measuring accelerations during the coupling process
E15 Measuring power transmission over the entire train
E16 Measuring the charge/discharge behaviour of the buffer batteries
E17 Replacing the electrical contacts
E18 Measuring the time course when establishing and breaking contact

Tests for data communication

The procedure for carrying out tests on data communication is similar to that for the tests on power supply. Furthermore, tests are being carried out for data communication in which the different groups of wagons are connected to create a greater running length for the signals. The screw couplings between the wagon groups are shunted here thanks to special adapter cables.

An overview of the test:

No. Communication system Type Single wagon/
train
D11 Powerline (before coupling tests) Channel measurement Single wagon
D12 Powerline (before coupling tests) Channel measurement Train
D13 CAN-FD Channel measurement Single wagon
D14 CAN-FD Channel measurement Train
D15 Powerline (after coupling tests) Channel measurement Single wagon
D16 Radio Channel measurement Single wagon
D17 CAN-FD (after coupling tests) Channel measurement Single wagon
D18 Powerline Data communication Single wagon
D19 Powerline Data communication Train
D20 CAN-FD Data communication Single wagon
D21 CAN-FD Data communication Train
D22 Radio Data communication Single wagon
D23 Radio Data communication Train

Climatic chamber tests

Climate chamber tests are carried out to check that the couplings function properly in extreme climatic conditions. During the climate chamber tests, the wagons are in the following loading condition (loading condition 1):

  • Eanos wagon: fully loaded
  • Hbbins wagon: empty
  • Zags wagon: empty

A critical situation is considered to be when two light (unloaded) wagons couple with ice without height offset (in this case the Zags wagon with the Hbbins wagon).

Successful establishment of the mechanical, pneumatic and electrical connections is tested.

During the tests, both the uncoupling behaviour of a connected air-conditioned coupling point and the coupling behaviour of two independently air-conditioned coupling heads are tested.

Test conditions

The conditions and temperatures under which the coupling and uncoupling behaviour is tested:

Temperature Ambient conditions Speed Number of repetitions
45°C Dry 2-5 km/h 5
45°C 90% humidity 2-5 km/h 5
0°C Wet (slush) 2-5 km/h 5
-5°C Wet (slush) 2-5 km/h 5
-10°C Dry 2-5 km/h 5
-10°C 3-5 mm of ice on coupling face, coupling (coupled) 2-5 km/h 5
-25°C Dry 2-5 km/h 5
-25°C 3-5 mm of ice on coupling face, coupling (coupled) 2-5 km/h 5
Test sequence

Before the actual test is carried out, the wagons are exposed to the temperature set in the climatic chamber and the selected climatic ambient conditions for a sufficient length of time. The middle wagon (Hbbins) is coupled to the Eanos wagon on one side and uncoupled from the Zags wagon on the other side (see figure on the right).

At the beginning of the tests, the two coupled wagons (Eanos and Hbbins) are uncoupled to check the uncoupling behaviour.

On the still uncoupled side of the Hbbins wagon, the Zags wagon is pushed on at approx. 2 to 5 km/h and a coupling process is carried out between the Zags and Hbbins wagons. This coupling point is then separated again and the Hbbins wagon is pushed onto the Eanos wagon and coupled with it again.

Now we’re back to the starting position again and the next test can be prepared.

Wagon configuration during test sequence