This manual contains notices you have to observe in order to ensure your personal safety, as well as to prevent
damage to property. The notices referring to your personal safety are highlighted in the manual by a safety alert
symbol, notices referring only to property damage have no safety alert symbol. These notices shown below are
graded according to the degree of danger.
DANGER
indicates that death or severe personal injury will result if proper precautions are not taken.
WARNING
indicates that death or severe personal injury may result if proper precautions are not taken.
CAUTION
indicates that minor personal injury can result if proper precautions are not taken.
NOTICE
indicates that property damage can result if proper precautions are not taken.
If more than one degree of danger is present, the warning notice representing the highest degree of danger will be
used. A notice warning of injury to persons with a safety alert symbol may also include a warning relating to property
damage.
Qualified Personnel
The product/system described in this documentation may be operated only by personnel qualified for the specific
task in accordance with the relevant documentation, in particular its warning notices and safety instructions. Qualified
personnel are those who, based on their training and experience, are capable of identifying risks and avoiding
potential hazards when working with these products/systems.
Proper use of Flender products
Note the following:
WARNING
Flender products may only be used for the applications described in the catalog and in the relevant technical
documentation. If products and components from other manufacturers are used, these must be recommended or
approved by Flender. Proper transport, storage, installation, assembly, commissioning, operation and maintenance
are required to ensure that the products operate safely and without any problems. The permissible ambient
conditions must be complied with. The information in the relevant documentation must be observed.
Trademarks
All names identified by ® are registered trademarks of Flender GmbH. The remaining trademarks in this publication
may be trademarks whose use by third parties for their own purposes could violate the rights of the owner.
Disclaimer of Liability
We have reviewed the contents of this publication to ensure consistency with the hardware and software described.
Since variance cannot be precluded entirely, we cannot guarantee full consistency. However, the information in
this publication is reviewed regularly and any necessary corrections are included in subsequent editions.
8.4Removing the coupling...........................................................................................................46
9Service and support....................................................................................................................................49
Table 4-1Types of preservative agents for long-term storage....................................................................22
Table 5-1Recommended assigned fits for bores with parallel key connection...........................................24
N-EUPEX / N-EUPEX DS 3100en
6Operating Instructions 10/2017
Page 7
Table of contents
Table 5-2Position of the parallel keyway....................................................................................................25
Table 5-3Diameter and axial position of the tapped hole, tightening torque..............................................27
Table 5-4Position of the tapped hole with respect to the parallel keyway..................................................28
Table 7-1Table of faults..............................................................................................................................38
These instructions describe the coupling and provide information about its handling - from
assembly to maintenance. Please keep these instructions for later use.
Please read these instructions prior to handling the coupling and follow the information in them.
1.2Text attributes
The warning notice system is explained on the back of the inner cover. Always follow the safety
information and notices in these instructions.
In addition to the warning notices, which have to be observed without fail, you will find the
following text attributes in these instructions:
1. Procedural instructions are shown as a numbered list. Always perform the steps in the order
given.
● Lists are formatted as bulleted lists.
– The dash is used for lists at the second level.
1
(1) Numbers in brackets are part numbers.
Note
A note is an important item of information about the product, the handling of the product or the
relevant section of the instructions. The note provides you with help or further suggestions/
ideas.
1.3Copyright
The copyright for these instructions is held by Flender.
These instructions must not be used wholly or in parts without our authorisation or be given to
third parties.
If you have any technical queries, please contact our factory or one of our service outlets (refer
to Service and support (Page 49)).
These instructions are part of the delivery. Always keep these instructions close to the coupling.
Please make sure that every person who is commissioned to work on the coupling has read
and understood these instructions prior to handling the coupling and observes all of the points.
Only the knowledge of these instructions can avoid faults on the coupling and ensure fault-free
and safe operation. Non-adherence to the instructions can cause product or property damage
or personal injury. Flender does not accept any liability for damage or operating failures that
are due to non-adherence to these instructions.
State of the art
The coupling described here has been designed in consideration of the latest findings for
demanding technical requirements. This coupling is state-of-the-art at the time of printing these
instructions.
In the interest of further development, Flender reserves the right to make such changes to the
individual components and accessories that increase performance and safety whilst
maintaining the essential features.
2
Symbols
Table 2-1General warnings
ISOANSIWarning
Warning - hazardous electrical voltage
Warning - explosive substances
---Warning - entanglement hazard
---Warning - hot surfaces
---Warning - substances that are harmful to health or are irritants
The couplings described here are “components” in accordance with the Machinery Directive
and do not require a declaration of incorporation.
ATEX Directive
Protective clothing
Using the coupling
The term "ATEX Directive" used in these instructions stands for the harmonisation legislation
of the European Union in compliance with the declaration of conformance for equipment and
protective systems for correct use in hazardous zones.
In addition to the generally prescribed personal protective equipment (safety shoes, overalls,
helmet, etc.), also wear suitable safety gloves and safety goggles when handling the coupling.
The relevant work safety and environmental protection regulations must be complied with at
all times during transport, assembly, installation, dismantling, operation and maintenance of
the coupling.
Only qualified personnel may operate, assemble, maintain and repair the coupling. Information
about qualified personnel can be found in the legal notes at the beginning of these instructions.
If lifting gear or load suspension devices are used for transporting, these have to be suitable
for the weight of the coupling.
If the coupling has visible damage, it may not be assembled or put into operation.
The coupling may only be operated in a suitable housing or with touch protection according to
applicable standards. This also applies to test runs and rotational direction checks.
Work on the coupling
Only carry out work on the coupling when it is not in operation and is not under load.
N-EUPEX / N-EUPEX DS 3100en
12Operating Instructions 10/2017
Page 13
Secure the drive unit against being switched on accidentally. Attach a notice to the switch
stating clearly that work is being carried out on the coupling. Ensure that the entire unit is not
under load.
2.2Intended use
Only use the coupling according to the conditions specified in the service and delivery contract
and the technical data in the annex. Deviating operating conditions are considered improper
use. The user or owner of the machine or plant is solely liable for any resulting damage.
When using the coupling please specifically observe the following:
● Do not make any modifications to the coupling that go beyond the permissible machining
described in these instructions. This also applies to touch protection facilities.
● Only use original spare parts from Flender. Flender only accepts liability for original spare
parts from Flender.
Other spare parts are not tested and approved by Flender. Non-approved spare parts may
possibly change the design characteristics of the coupling and thus impact active and/or
passive safety.
Flender will accept no liability or warranty whatsoever for damage occurring as a result of
the use of non-approved spare parts. The same applies to any accessories that were not
supplied by Flender.
Safety instructions
2.2 Intended use
If you have any queries, please contact our customer service (see Service and support
(Page 49)).
2.3Safety instructions for a coupling for use in potentially explosive
atmospheres
2.3.1Marking
You can find a description of the coupling parts in chapter Description (Page 19).
A coupling designed in accordance with the ATEX Directive has a marking on the coupling
parts.
Coupling part 1 without electrically insulating flexible elements
One of the following markings is visible on the outer diameter of coupling part 1:
2.3 Safety instructions for a coupling for use in potentially explosive atmospheres
Version 2:
Flender GmbHII 2G c IIC T4/T5/T6
-30 °C ≤ Ta ≤ +80 °C/+70 °C/+55 °C
46393 Bocholt - GermanyII 2D c T 110 °C -30 °C ≤ Ta ≤ +80 °C
FLENDER couplings N‑EUPEX <Year of man‐
ufacture>
Coupling part 1 with flexible elements for low-temperature use
One of the following markings is visible on the outer diameter of coupling part 1:
Version 1:
Flender GmbHII 2GD c IIC TX
46393 Bocholt - GermanyI M2 c X
FLENDER couplings N‑EUPEX <Year of man‐
ufacture>
Version 2:
Flender GmbHII 2G c IIC T6 -50 °C ≤ Ta ≤ +50 °C
46393 Bocholt - GermanyII 2D c T 80 °C -50 °C ≤ Ta ≤ +50 °C
FLENDER couplings N‑EUPEX <Year of man‐
ufacture>
I M2 c -30 °C ≤ Ta ≤ +80 °C
I M2 c -50 °C ≤ Ta ≤ +50 °C
Coupling part 1 with electrically insulating flexible elements
One of the following markings is visible on the outer diameter of coupling part 1:
Version 1:
Flender GmbHII 2GD c IIB TX
46393 Bocholt - GermanyI M2 c X
FLENDER couplings N‑EUPEX <Year of man‐
ufacture>
Version 2:
Flender GmbHII 2G c IIB T4/T5/T6
46393 Bocholt - GermanyII 2D c T 110 °C -30 °C ≤ Ta ≤ +80 °C
FLENDER couplings N‑EUPEX <Year of man‐
ufacture>
14Operating Instructions 10/2017
-30 °C ≤ Ta ≤ +80 °C/+70 °C/+55 °C
I M2 c -30 °C ≤ Ta ≤ +80 °C
N-EUPEX / N-EUPEX DS 3100en
Page 15
Coupling part 2 or 4
Safety instructions
2.3 Safety instructions for a coupling for use in potentially explosive atmospheres
Coupling part 2 or coupling part 4 is stamped with
Undrilled or predrilled coupling
A coupling part with Ex marking, the letter "U" and the Flender order number has been delivered
undrilled or predrilled.
Note
Undrilled or predrilled coupling with Ex marking
Flender only supplies an undrilled or predrilled coupling with Ex marking on the condition that
the customer assumes the responsibility and liability for correct finishing work in a declaration
of exemption.
2.3.2Conditions of use
Note
Note also the material-dependent permissible ambient temperature of the flexible elements
(12) in accordance with sections N-EUPEX flexible elements (12) (Page 65) and N-EUPEX
DS flexible elements (12) (Page 66).
.
A coupling designed in accordance with the ATEX Directive is suitable for the following
conditions of use:
● Equipment group I
– Category M2
● Equipment group II
– Category 2 and 3
– Group of substances G, zone 1 and 2
– Group of substances D, zone 21 and 22
– Explosion group IIA, IIB and IIC
– Explosion group IIA and IIB when electrically insulating flexible elements are used
Conditions of use for products with TX marking
The maximum ambient temperature stated in the following tables applies to the temperature
in the direct vicinity of the coupling and the temperature of adjacent components.
Check the ambient temperature for use of the coupling in the relevant temperature class.
Table 2-2Temperature classes (TX) for explosive atmospheres as a result of gases, vapours or mists
2. Dust/air mixtures
Check the ambient temperature.
Table 2-3Maximum surface temperature (TX) for an explosive atmosphere as a result of dust/air
Max. ambient temperatureTemperature class
80 °CT4
70 °CT5
55 °CT6
mixtures
Max. ambient temperatureMax. surface temperature
80 °C110 °C
Notes concerning operation of the coupling in potentially explosive atmospheres
● Only use the coupling underground in mines in potentially explosive atmospheres together
with drive motors that can be switched off in the event of the formation of an explosive
atmosphere.
● Earth machines that are connected via the coupling with a leakage resistance of less than
106 Ω.
● If you want to use a coated coupling in potentially explosive atmospheres, please note the
requirements concerning the conductivity of the paint and the limitation on the paint layer
thickness applied in accordance with EN 13463-1. No build-up of electrostatic charges is
to be expected with a paint layer thickness of less than 200 μm.
2.4General warning notices
DANGER
Danger due to bursting of the coupling
The coupling may burst if it is not used properly. There is a risk of fatal injury from flying
fragments. Bursting of the coupling can lead to an explosion in potentially explosive
atmospheres.
● Use the coupling for the purpose for which it is intended.
N-EUPEX / N-EUPEX DS 3100en
16Operating Instructions 10/2017
Page 17
Safety instructions
2.4 General warning notices
DANGER
Risk of explosion when using coupling parts without Ex marking
Coupling parts without Ex marking have not been approved for use in potentially explosive
atmospheres. These coupling parts can lead to an explosion during operation.
● Only use couplings with Ex marking in potentially explosive atmospheres.
DANGER
Danger
Risk of injury due to the use of unsuitable and/or damaged components. The use of unsuitable
and/or damaged components can lead to an explosion in potentially explosive atmospheres.
● Observe the information regarding conditions of use.
DANGER
Danger of explosion
Improper operation of the coupling can lead to an explosion in potentially explosive
atmospheres.
● Please observe the notes concerning operation of the coupling in potentially explosive
atmospheres.
DANGER
Danger from hot coupling parts
Risk of injury due to hot surfaces. Hot coupling parts can lead to an explosion in potentially
explosive atmospheres.
The N‑EUPEX or N‑EUPEX DS couplings described here are torsionally flexible, damping pin
couplings and are available in various types and sizes. The couplings can be used in
accordance with the ATEX Directive in potentially explosive atmospheres if they have a CE
marking.
Types A and B are fail-safe. Types ADS and BDS have no fail-safe device.
These instructions describe the assembly and operation of an N‑EUPEX or N‑EUPEX DS
coupling arranged horizontally with a shaft-hub connection made by a cylindrical or conical
bore with parallel key. Please consult Flender if you want to use a different type of installation.
N‑EUPEX couplings are designed for use in all kinds of machines.
N‑EUPEX DS couplings are used for applications which require the input and output to be
disconnected from one another in the event of destruction of the flexible elements.
The diagrams show the various types with their constituent parts and their part numbers.
The coupling, unless not specifically ordered otherwise, is supplied with preservation and can
be stored for up to 3 months.
Note
Information about storing the coupling
● Ensure that the storage room is dry (relative humidity < 65 %) and free of dust.
● Ensure that there is no condensation.
● Do not store the coupling together with corrosive chemicals, acids, caustic solutions, etc.
● If the coupling contains elastomer components, ensure that there are no devices in the
storage room that produce ozone, such as fluorescent lights, mercury vapour lamps or highvoltage electrical equipment.
● Store the coupling on suitable supports or in suitable containers.
Long-term storage
NOTICE
Property damage due to improper long-term storage
Negative changes to the physical properties of the coupling and/or coupling damage.
● Note the handling instructions for long-term storage.
1. You can find the required type of preservative agent in the following table (types of
preservative agents for long-term storage).
2. Remove the elastomer components. These must not come into contact with cleaning agents
and long-term preservative agents.
3. Clean the coupling parts.
4. Apply the stipulated preservative agent.
5. Store the coupling parts and the elastomer components separately.
Table 4-1Types of preservative agents for long-term storage
Oil sprayAnti-corrosion agentUp to 12 monthsUp to 4 months
Tectyl 846 or similarLong-term preservative agent on
wax basis
Emulsion cleaner + VCI foilActive system, reusableUp to 5 yearsUp to 5 years
Up to 36 monthsUp to 12 months
N-EUPEX / N-EUPEX DS 3100en
22Operating Instructions 10/2017
Page 23
Assembly
5
Assembly of the coupling comprises the following steps:
● Preparatory work (Page 23)
● Assembling the coupling (Page 30)
● Aligning the coupling (Page 31)
DANGER
Danger due to bursting of the coupling
If you do not observe the information stipulated here regarding assembly, this can lead to
bursting of the coupling during operation. There is a risk of fatal injury from flying fragments.
Bursting of the coupling can lead to an explosion in potentially explosive atmospheres.
● Please observe all the stipulations concerning assembly.
Note
Information about the assembly of the coupling
● Only use undamaged components for the assembly of the coupling.
● Follow the assembly sequence.
● Please ensure that there is sufficient space at the assembly location and that the location
is tidy and clean in order to be able to assemble and maintain the coupling without any risk.
● If a dimension drawing has been created for the coupling, please observe the information
it contains as a matter of priority.
5.1Preparatory work
Note
Please consult Flender if you want to machine a conical finished bore.
Carry out the following steps if the coupling does not have a finished bore:
The customer is responsible for execution of the finishing work on the coupling. Flender shall
have no liability whatsoever for claims under warranty arising from finishing work that has not
been carried out adequately.
5.1.1Milling the parallel keyway
The diameter of the finished bore depends on the shaft used.
Recommended assigned fits
In the following table you can find the recommended assigned fits for bores with a parallel key
connection. The assigned fit m6 / H7 is especially suitable for a host of applications.
Table 5-1Recommended assigned fits for bores with parallel key connection
Procedure
DescriptionPush fitPress fitInterference fit
Not suitable for reversing operationSuitable for reversing operation
Shaft tolerancej6h6h6k6m6n6h6
Bore toleranceH7J7K7H7H7H7M7
1. Remove the flexible elements (12).
2. Remove the preservation and clean the coupling parts 1 (1) and 2 (2) or 4 (4) to be machined.
3. Clamp the coupling to the areas marked with
in the diagram below.
4. Machine the finished bore in accordance with the diagram below.
Note
Diameter of the finished bore
The diameter of the finished bore may not exceed the specified maximum diameter.
● Please observe the maximum diameters specified in section Speeds, geometry data
and weights (Page 57).
N-EUPEX / N-EUPEX DS 3100en
24Operating Instructions 10/2017
Page 25
,7$
$
'7,%7,
,7&
,7&
'&%
7,7,7,7,
ෘ'
ෘ'
ෘ'
ෘ'
①Coupling part 1
②Coupling part 4
③Coupling part 2
④Coupling part 2/3
Figure 5-1Tolerances for finished bore
Assembly
5.1 Preparatory work
5.1.2Milling the parallel keyway
Position of the parallel keyway
The table below states the required position for the parallel keyway in the coupling parts
depending on the coupling type.
Table 5-2Position of the parallel keyway
Coupling partCouplingPosition of the parallel keyway
1N‑EUPEXCentred between the flexible element webs
1N‑EUPEX DSCentred between the flexible element pockets
2N‑EUPEXCentred between the tapped holes
2N‑EUPEX DSCentred between the tapped holes and offset relative to the
● If the coupling is intended for use under normal operating conditions, mill the parallel
keyway according to DIN 6885/1 ISO JS9.
● If the coupling is intended for reversing operation, mill the parallel keyway according to
DIN 6885/1 ISO P9.
● If you want to mill a parallel keyway that does not correspond to DIN 6885/1, please consult
Flender.
5.1.3Machining an axial locking mechanism
The coupling part is secured by a set screw or an end plate to prevent axial movements.
Please consult Flender if you want to use an end plate.
Note the following when using a set screw:
● Diameter and axial position of the tapped hole in the hub
● Position of the tapped hole with respect to the parallel keyway
● Selection of the set screw
Diameter and axial position of the tapped hole in the hub
The following diagram shows the axial position of the tapped hole.
①Coupling part 1; axial position of the tapped hole up to size 125 / 135
②Coupling part 1; axial position of the tapped hole as of size 140 / 152
③Coupling part 2
④Coupling part 4
Figure 5-2Diameter and axial position of the tapped hole in the hub
26Operating Instructions 10/2017
N-EUPEX / N-EUPEX DS 3100en
Page 27
Assembly
5.1 Preparatory work
The following table contains the values for the diameter and axial position of the tapped hole
depending on the size of the coupling.
Table 5-3Diameter and axial position of the tapped hole, tightening torque
Size
d1
58 / 66M510--83
68 / 76M610--84
80 / 88M611--124
95 / 103M615--154
110 / 118M618-9184
125 / 135M820-12208
140 / 152M8-1315228
160 / 172M10-13202515
180 / 194M12-16303225
200 / 218M12-20304025
225 / 245M12-22354025
250 / 272M16-24404570
280 / 305M16-28454570
315 / 340M16-3550-70
350 / 380M20-4060-130
400 / 430M20-5070-130
440 / 472M24-6080-230
480 / 514M24-7090-230
520 / 556M24-80100-230
560M24-75100-230
610M24-85110-230
660M24-100130-230
710M24-115140-230
e1
mm
e2
mm
e3
mm
e4
mm
Tightening torque
T
Nm
A
Apply the recommended tightening torques in accordance with the stipulations in section
Tightening procedure (Page 64).
Position of the tapped hole with respect to the parallel keyway
The tapped hole for the set screw is generally positioned on the parallel keyway. This does
not apply to the coupling parts listed in the following table.
Table 5-4Position of the tapped hole with respect to the parallel keyway
Coupling partSizeFinished bore
Selection of the set screw
CAUTION
Physical injury
Danger of injury from protruding set screw.
● Please observe the information about selecting the set screw.
As set screws use threaded studs in accordance with ISO 4029 with a toothed cup point. The
size of the set screw is determined by the bore made. The set screw should fill out the tapped
hole as much as possible and must not protrude beyond the hub.
Position of the tapped hole
[mm]
158 / 66≥ 15Offset 180° relative to parallel keyway
68 / 76≥ 20Offset 144° relative to parallel keyway
80 / 88≥ 25Offset 180° relative to parallel keyway
95 / 103≥ 38Offset 180° relative to parallel keyway
2110 / 118≥ 30Offset 180° relative to parallel keyway
458 / 66≥ 18Offset 180° relative to parallel keyway
68 / 76≥ 20Offset 180° relative to parallel keyway
5.1.4Balancing the coupling
Notes on balancing the coupling
NOTICE
Damage to coupling part 1 (1)
If you completely drill through the base of a flexible element pocket on coupling part 1 (1),
then coupling part 1 (1) is no longer allowed to be used for operation.
● Please observe the stipulations about machining the balancing hole.
N-EUPEX / N-EUPEX DS 3100en
28Operating Instructions 10/2017
Page 29
Assembly
5.1 Preparatory work
Please note the following when balancing the coupling:
● Select the balancing quality according to the application (but at least G16 in accordance
with DIN ISO 21940).
● Observe the balancing specification according to DIN ISO 21940-32.
● Machine the balancing bore on a large radius with adequate clearance to the flexible
element webs / pockets and to the cams and the outer circumference.
①Balancing bore
②Part 1 for N‑EUPEX or N‑EUPEX DS coupling
③Part 2 for N‑EUPEX or N‑EUPEX DS coupling
④Part 4 for N‑EUPEX or N‑EUPEX DS coupling
Figure 5-3Position of the balancing bore for single-plane balancing
①Balancing bore
②Part 1 for N‑EUPEX or N‑EUPEX DS coupling
③Part 2 for N‑EUPEX or N‑EUPEX DS coupling
④Part 4 for N‑EUPEX or N‑EUPEX DS coupling
Figure 5-4Position of the balancing bore for two-plane balancing
Note
A better balancing result can be achieved by balancing the coupling parts (2 and 3) when they
are bolted together as an assembly. When balancing all parts together, mark the position of
the components relative to one another.
Damage to the elastomer components from cleaning agents.
● Ensure that the elastomer components do not come into contact with cleaning agents.
NOTICE
Property damage
Damage to the shaft end, the coupling parts and/or the parallel key.
● Note the following handling instruction.
Procedure
1. Unscrew the set screw until it is no longer possible for there to be a collision with the parallel
key or the shaft.
2. Clean the bores and shaft ends.
3. Coat the bores of coupling parts 1 (1) and 2 (2) or 4 (4) and the shafts with MoS2 assembly
paste (e.g. Microgleit LP 405).
4. If you have dismantled the coupling part 3 (3), mount the coupling part 3 (3) on the shaft
before fitting the coupling part 2 (2).
5. Mount the coupling parts 1 (1) and 2 (2) or 4 (4) on the shaft.
Note
Coupling parts with conical bore
Mount the coupling parts 1 (1) and 2 (2) or 4 (4) with conical bore and parallel keyway on
the shaft in cold condition. Secure the coupling parts with suitable end plates without pulling
the coupling parts further onto the cone (fitting dimension = 0).
Note
Coupling parts with cylindrical bore
To make assembly easier, you can heat coupling parts 1 (1) and 2 (2) or 4 (4) with cylindrical
bore up to a maximum of 150 °C if required. Note when doing this the temperature range
of the flexible elements (12) (see sections N-EUPEX flexible elements (12) (Page 65)and
N-EUPEX DS flexible elements (12) (Page 66)). Remove the flexible elements (12) if
necessary. Protect adjacent components against damage and heating to temperatures
above 80 °C.
6. Secure the coupling parts 1 (1) and 2 (2) or 4 (4) with a set screw or an end plate. When
securing with a set screw the shaft must not protrude or be set back from the inner side of
the hub.
N-EUPEX / N-EUPEX DS 3100en
30Operating Instructions 10/2017
Page 31
7. Tighten up the set screw or the screw to attach the end plate to the specified tightening
torque TA (for the set screw please see section Machining an axial locking mechanism
(Page 26)).
8. If you have removed the flexible elements (12), reinstall them.
9. Tighten the bolts in the coupling part 2 (2) and 3 (3) to the specified torque TA (see section
Tightening torques and widths A/F (Page 63)).
5.3Aligning the coupling
5.3.1Purpose of alignment
The shafts that are joined by the coupling are never on an ideal precise axis but have a certain
amount of misalignment.
Misalignment in the coupling leads to restoring forces that can stress adjacent machine parts
(e.g. the bearings) to an unacceptable extent.
Assembly
5.3 Aligning the coupling
The misalignment values in operation result from the following:
● Misalignment due to assembly
Incorrect position due to a lack of precision when aligning
During use in potentially explosive atmospheres deposits from heavy metal oxides (rust) can
ignite due to friction, impact or friction sparks and lead to an explosion.
● Ensure through the use of an enclosure or other suitable measures that the deposition of
heavy metal oxides (rust) on the coupling is not possible.
In order to ensure safe commissioning, carry out various tests prior to commissioning.
Testing before commissioning
DANGER
Danger
Overload conditions can occur during the commissioning of the coupling. The coupling can
burst and metal parts can be flung out. There is a risk of fatal injury from flying fragments.
Bursting of the coupling can lead to an explosion in potentially explosive atmospheres.
● Carry out the tests prior to commissioning.
● Do not touch the rotating coupling.
6
1. Check the tightening torques of the screws of the coupling in accordance with section
Tightening torques and widths A/F (Page 63).
2. Check the tightening torques of the foundation bolts of the coupled machines.
3. Check whether the enclosures (coupling guard, touch protection) have been installed and
that the function of the coupling has not been adversely affected by the enclosure. This
also applies to test runs and rotational direction checks.
The coupling runs quietly and shock-free during normal operation.
7.2Faults - causes and rectification
A form of behaviour which is different to normal operation is classed as a fault and has to be
rectified immediately.
Look out specifically for the following faults during coupling operation:
● Unusual coupling noise
● Sudden occurrence of shocks
7.2.1Procedure in the event of malfunctions
7
DANGER
Danger due to bursting of the coupling
There is a risk of fatal injury from flying fragments. Bursting of the coupling can lead to an
explosion in potentially explosive atmospheres.
● Switch off the unit at once if any malfunctions occur.
● Note during the maintenance work the possible causes of faults and the notes on rectifying
them.
Proceed as described below if there is a malfunction of the coupling during operation:
1. De-energise the drive immediately.
2. Initiate the required action for repair, taking into consideration the applicable safety
regulations.
If you cannot determine the cause or if you cannot carry out repair work with your own means,
request one of our customer service technicians.
7.2.2Identifying the fault cause
Faults occur frequently due to application errors or they occur due to operational circumstances
such as wear of wearing parts or changes to the system.
The faults and fault causes listed below only serve as an indication for troubleshooting. In the
case of a complex system be sure to include all the system components in the search for the
fault.
WARNING
Physical injury
Injury from rotating parts.
● Only carry out work on the coupling when it is not moving.
● Secure the drive unit against being operated accidentally.
● Attach a notice to the switch stating clearly that work is being carried out on the coupling.
● Before starting any work, make sure that the unit is free from loads.
Intended use
The coupling is only approved for the applications specified in these instructions. Please
observe all the stipulations in section Intended use (Page 13).
7.2.2.1Possible faults
Table 7-1Table of faults
FaultCauseRectification
Sudden changes in the noise level and/
or sudden occurrences of shocks
Wear of wearing partsFollow the instructions given in section
Replacing wearing parts (Page 40).
Changed alignmentFollow the instructions given in section
Correcting the changed alignment
(Page 41).
Coupling not suitable for the operating
conditions.
Check the possible causes given in sec‐
tion Unsuitable coupling (Page 39).
Incorrect assembly of the coupling.
Check the possible causes given in sec‐
tions Assembly-related causes
(Page 39) and Specific installation-rela‐
ted and maintenance-related causes
(Page 40).
Incorrect maintenance of the coupling.
Check the possible causes given in sec‐
tions Maintenance-related causes
(Page 40) and Specific installation-rela‐
ted and maintenance-related causes
(Page 40).
Use a coupling that is suitable for the
operating conditions.
Reassemble the coupling in accordance
with these instructions.
Please observe all the stipulations and
requirements given in chapter Assem‐
bly (Page 23).
Please observe all the stipulations and
requirements given in chapter Servic‐
ing (Page 43).
N-EUPEX / N-EUPEX DS 3100en
38Operating Instructions 10/2017
Page 39
7.2 Faults - causes and rectification
FaultCauseRectification
Presence of vibrationCoupling not suitable for the operating
conditions.
Check the possible causes given in sec‐
tion Unsuitable coupling (Page 39).
Incorrect assembly of the coupling.
Check the possible causes given in sec‐
tions Assembly-related causes
(Page 39) and Specific installation-rela‐
ted and maintenance-related causes
(Page 40).
Incorrect maintenance of the coupling.
Check the possible causes given in sec‐
tions Maintenance-related causes
(Page 40) and Specific installation-rela‐
ted and maintenance-related causes
(Page 40).
Use a coupling that is suitable for the
operating conditions.
Reassemble the coupling in accordance
with these instructions.
Please observe all the stipulations and
requirements given in chapter Assem‐
bly (Page 23).
Please observe all the stipulations and
requirements given in chapter Servic‐
ing (Page 43).
7.2.2.2Possible causes
Operation
Unsuitable coupling
● Important information on the description of the drive unit and the environment were not
● System torque too high and/or torque dynamics not permissible.
● System speed too high.
● Application factor not selected correctly.
● Chemically aggressive environment not taken into consideration.
● Coupling not suitable for the ambient temperature.
● Diameter and/or assigned fit of the finished bore not permissible.
● Width across corners of the parallel keyways greater than the width across corners of the
● Shaft-hub connection incorrectly sized.
● Maximum permissible load conditions not taken into consideration.
● Maximum permissible overload conditions not taken into consideration.
● Dynamic load conditions not taken into consideration.
● Coupling and the machine and/or drive train form a critical torsional, axial or bending
available when the coupling was chosen.
parallel keyways in accordance with DIN 6885/1 for the maximum permissible bore.
vibration system.
Assembly-related causes
● Damaged parts installed.
● Shaft diameter outside the stipulated tolerance range.
● Coupling parts interchanged and hence not assigned to the specified shaft.
● Stipulated locking elements to prevent axial movements not installed.
● Stipulated tightening torques not adhered to.
● Bolts inserted dry or greased.
● Flange surfaces of screwed connections not cleaned.
● Alignment and/or shaft misalignment values not set in accordance with the instructions.
● Coupled machines were not correctly connected to the foundation so that a shifting of the
machines leads to an impermissible displacement of the coupling parts.
● Coupled machines not earthed adequately.
● Coupling guard used is not suitable.
Maintenance-related causes
● Stipulated maintenance intervals not adhered to.
● Spare parts that were used were not original spare parts from Flender.
● Flender spare parts that were used were old or damaged.
● Leak in the area of the coupling not detected so that chemically aggressive substances
damage the coupling.
● Indications of faults, such as noise or vibration, were not heeded.
● Stipulated tightening torques not adhered to.
● Alignment and/or shaft misalignment values not set in accordance with the instructions.
Specific installation-related and maintenance-related causes
● Flexible elements (12) not fitted.
● Fitted flexible elements (12) heated up excessively when applying heat to the coupling parts.
● Flexible elements (12) are of different types or age.
● Flexible elements (12) not replaced as sets.
7.2.3Correcting faults
7.2.3.1Replacing wearing parts
Flexible elements (12) are subject to wear and this wear can result in torsional backlash.
N-EUPEX / N-EUPEX DS 3100en
40Operating Instructions 10/2017
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Procedure
1. Check the wear on the flexible elements (12) (see section Maximum permissible torsional
backlash (Page 44)).
2. Replace the flexible elements (12) if necessary (see section Replacing wearing parts
(Page 45)).
7.2.3.2Correcting the changed alignment
A changed alignment of the coupling during operation often occurs when the coupled machines
shift towards one another. A cause of this can be loose foundation bolts.
Procedure
1. Correct the cause for the change in alignment.
2. Check the wearing parts for wear and replace them as required.
3. Check the locking elements that prevent axial movements and correct these as required.
The coupling can burst if the maintenance intervals are not adhered to. There is a risk of fatal
injury from flying fragments. Bursting of the coupling can lead to an explosion in potentially
explosive atmospheres.
● Please observe all the stipulations concerning maintenance of the coupling in this section.
DANGER
Danger due to bursting of the coupling
The coupling can burst if the maximum permitted torsional backlash is exceeded. There is a
risk of fatal injury from flying fragments. Bursting of the coupling can lead to an explosion in
potentially explosive atmospheres.
● Note also the actual wear of the elastomer components.
8
WARNING
Physical injury
Injury from rotating parts.
● Only carry out work on the coupling when it is not moving.
● Secure the drive unit against being operated accidentally.
● Attach a notice to the switch stating clearly that work is being carried out on the coupling.
● Before starting any work, make sure that the unit is free from loads.
Check the torsional backlash between the coupling parts at the specified maintenance
intervals. The maximum permissible torsional backlash for the various coupling sizes can be
found in section Maximum permissible torsional backlash (Page 44).
Table 8-1Maintenance intervals
TypeInitial maintenanceFollow-up maintenance
A3 months after commissioningEvery 12 months
B
ADS3 months after commissioning
BDS
1)
According to the ATEX Directive, need only be inspected if a failure of the flexible elements (12) and
shutdown of the drive as a result of this failure could give rise to a risk of explosion. We recommend
that the torsional backlash is checked regularly.
If necessary, set shorter maintenance intervals depending on actual wear.
8.2Maximum permissible torsional backlash
In order to calculate the torsional backlash, rotate one coupling part without applying torque
up to the stop. Mark both of the coupling halves in the way shown in the diagram below. Turn
the coupling part in the opposite direction up to the stop. The markings on both halves will then
move apart. The distance between the markings corresponds to the torsional backlash.
Figure 8-1Markings for calculating the torsional backlash
Table 8-2Maximum permissible torsional backlash for the types A and B (sizes 58 to 250)
Size58688095110125140160180200225250
Maximum permissible
torsional backlash ΔS
[mm]
Table 8-3Maximum permissible torsional backlash for the types A and B (sizes 280 to 710)
Size280315350400440480520560610660710
Maximum permissible
torsional backlash ΔS
[mm]
Table 8-4Maximum permissible torsional backlash for the types ADS and BDS (sizes 66 to 218)
Size667688103118135152172194218
Maximum permissible
torsional backlash ΔS
[mm]
5.55.55.06.07.08.08.08.08.08.59.010.0
V
11.510.511.513.014.015.517.517.519.521.022.5
V
6.07.05.07.09.010.511.59.08.07.0
V
N-EUPEX / N-EUPEX DS 3100en
44Operating Instructions 10/2017
Page 45
Table 8-5Maximum permissible torsional backlash for the types ADS and BDS (sizes 245 to 556)
Size245272305340380430472514556
Maximum permissible
torsional backlash ΔS
[mm]
6.57.08.06.57.010.012.014.016.0
V
8.3Replacing wearing parts
DANGER
Danger due to bursting of the coupling
If you do not observe the information stipulated here regarding replacement of wearing parts,
this can lead to bursting of the coupling during operation. There is a risk of fatal injury from
flying fragments. Bursting of the coupling can lead to an explosion in potentially explosive
atmospheres.
● Please observe all the stipulations concerning the replacement of wearing parts.
Servicing
8.3 Replacing wearing parts
Types A and ADS
Replace the flexible elements (12) if the maximum permissible torsional backlash has been
reached. The method used to replace the flexible elements (12) varies according to the
coupling type.
Replace the flexible elements (12) without moving the coupled machines.
1. Undo the connection between coupling parts 2 (2) and 3 (3).
2. Move the coupling part 3 (3) axially.
The flexible elements (12) are freely accessible after coupling part 2 (2) has been turned.
Note
Loosening coupling part 3 (3)
To make it easier to loosen coupling part 3 (3), a tapped jacking hole is machined in coupling
part 1 (1) on coupling sizes 225 to 430. As of coupling size 440, the tapped jacking hole is
machined in coupling part 3 (3).
①Tapped jacking hole in coupling part 1
②Tapped jacking hole in coupling part 3
Figure 8-2Tapped jacking hole for loosening coupling part 3 (3)
4. Install the new flexible elements (12).
Please observe the information in section Use and storage of flexible elements (12)
(Page 64) when replacing flexible elements (12).
When reinstalling the coupling parts please observe the information in chapters Assembly
(Page 23) and Commissioning (Page 35).
Types B and BDS
1. In order to replace the flexible elements (12), move the coupled machines apart.
2. Remove the flexible elements (12).
3. Install the new flexible elements (12).
Please observe the information in section Use and storage of flexible elements (12)
(Page 64) when replacing flexible elements (12).
When reinstalling the coupling parts please observe the information in chapters Assembly
(Page 23) and Commissioning (Page 35).
8.4Removing the coupling
DANGER
Danger from burners and hot coupling parts
Risk of injury due to burners and hot surfaces. Burners or hot coupling parts can lead to an
explosion in potentially explosive atmospheres.
● Ensure that the area is not at risk of explosion.
Procedure
1. Move the coupled machines apart.
2. Secure the coupling parts to prevent them from falling.
3. Remove the axial locking elements (set screw, end plate).
4. Use a suitable pulling fixture.
5. Heat up the coupling part 1 (1) and 2 (2) or 4 (4) using a burner above the parallel keyway
along its length to maximum 80 °C.
Note when doing this the temperature range of the flexible elements (12) (see sections NEUPEX flexible elements (12) (Page 65)and N-EUPEX DS flexible elements (12)
(Page 66)). Remove the flexible elements if necessary.
6. Pull off the coupling part. Use suitable lifting gear when doing this.
7. Check the hub bore and the shaft for damage and protect them against corrosion.
8. Replace any damaged parts.
N-EUPEX / N-EUPEX DS 3100en
46Operating Instructions 10/2017
Page 47
Servicing
8.4 Removing the coupling
When reinstalling the coupling parts please observe the information in chapters Assembly
(Page 23) and Commissioning (Page 35).
When ordering spare parts, requesting a customer service technician or in the case of technical
queries, please contact our factory or one of our customer service addresses:
By stocking the most important spare parts at the installation site you can ensure that the
coupling is ready for use at any time.
Note
Original spare parts
Only use original spare parts from Flender. Flender only accepts liability for original spare parts
from Flender.
Other spare parts are not tested and approved by Flender. Non-approved spare parts may
possibly change the design characteristics of the coupling and thus impact active and/or
passive safety.
Flender will accept no liability or warranty whatsoever for damage occurring as a result of the
use of non-approved spare parts. The same applies to any accessories that were not supplied
by Flender.
You can find the available spare parts for the coupling described here at Spare parts drawing
and spare parts list (Page 54).
11
You will find our contact data for ordering spare parts in Service and support (Page 49).
Information required when ordering spare parts
● Flender order number with item
● Flender drawing number
● Coupling type and size
● Part number (refer to Spare parts drawing and spare parts list (Page 54))
● Dimensions of the pare part, for example:
– Bore
– Bore tolerance
– Parallel keyway and balancing
● Special dimensions, for example, flange connection dimensions, intermediate sleeve length
Tighten fastening screws to the specified tightening torque in accordance with the following
table:
Table A-7Tightening procedure
Scatter of the torque applied
at the tool
±5 %
Tightening procedure
(As a rule, the tightening procedures listed are within the specified tool
torque scatter)
● Hydraulic tightening with mechanical screwdriver
● Torque-controlled tightening with a torque wrench or a torque
wrench that gives a signal
● Tightening with a precision mechanical screwdriver with dynamic
torque measurement
The tightening torques apply to screws/bolts with untreated surfaces that are not oiled or are
only lightly oiled, and for screws/bolts that are used with a liquid screw locking agent in
accordance with these instructions. Use with lubricant paint or lubricant is not permitted.
A.5Flexible elements (12)
A.5.1Use and storage of flexible elements (12)
Note the following concerning the use and storage of the flexible elements (12):
● Storage possible for up to 5 years
● Protect against direct sunlight, artificial light with a high UV‐content and extreme
temperatures
● Avoid contact with aggressive media
● Only replace complete sets
● Only use flexible elements of the same type and age
FLENDER N-EUPEX-DS®
couplings
Types A, B and ADS, BDS
Name and address of the manufacturer:
Flender GmbH
Schlavenhorst 100
46395 Bocholt
Deutschland – Germany
This declaration of conformity is issued under the sole responsibility of the manufacturer.
Object of the declaration is the product specified above.
The object of the declaration described above is in conformity with the relevant harmonisation
legislation of the Union:
– Directive 2014/34/EU Official Journal L 96, 29.3.2014, pages 309-356
Harmonised standards or other technical specifications, on which the declaration of conformity is
based:
EN 1127‐1: 2011
EN 1710: 2008
EN 13463‐1: 2009
EN 13463‐5: 2011
The notified body, DEKRA EXAM GmbH, code number 0158, has received the technical
documentation.