Ministry of Defence
Defence Standard 22-26 (NES 2026)
Issue 1 Publication Date 1 April 2000
Specification for the Type X Resilient
Mount and the Leaf Spring Assembly of the
Type Y Resilient Mount
Incorporating NES 2026 Category 2
Issue 2 Publication Date August 1994
Ministry of Defence
Sea Systems Controllerate
Naval Engineering Standard
NES 2026
Issue 2
August 1994
SPECIFICATION FOR THE TYPE 'X' RESILIENT MOUNT
AND THE LEAF SPRING ASSEMBLY
OF THE TYPE 'Y' RESILIENT MOUNT
This NES Supersedes
NES 2026 ISSUE 1
Record of Amendments
AMDT
1
2
3
4
5
6
7
8
9
10
INSERTED BY
DATE
ISSUE2
SPECIFICATION FOR THE TYPE 'X' RESILIENT MOUNT
AND THE LEAF SPRING ASSEMBLY OF
THE TYPE 'Y' RESILIENT MOUNT
The issue and use of this Standard
is authorized on behalf of the
Controller of the Navy and the
Chief of Fleet Support by :
Assistant Director Naval Architecture Signature Reduction
© COMPTROLLER OF HMSO 1994
Published by:
Procurement Executive, Ministry of Defence
Sea Systems Controllerate
Foxhill Bath BA1 5AB
D313 .94
(i)
NES 2026
Issue 2
CONDITIONS OF RELEASE
General
1.
This Naval Engineering Standard (NES) has been prepared for the use of the Crown and
of its contractors in the execution of contracts for the Crown . The Crown hereby excludes
all liability (other than liability for death or personal injury) whatsoever and howsoever
arising (including but without limitation, negligence on the part of the Crown, its servants
or agents) for any loss or damage however caused where the NES is used for any other
purpose .
2.
This document is Crown Copyright and the information herein may be sub ect to Crown
or third party rights . It is not to be released, reproduced or published without written
permission of the MOD .
3.
The Crown reserves the right to amend or modify the contents of this NES without
consulting any holder .
MOD Tender or Contract Process
4.
This NES is the property of the Crown and unless otherwise authorized in writing by the
MOD must be returned on completion of the contract, or submission of tender, in
connection with which it is issued.
5.
When this NES is used in connection with a tender or contract, the user is to ensure that
he is in possession of the appropriate version of each document, including related
documents, relevant to each particular tender or contract . Enquiries in this connection
may be made of the local MOD(PE) Quality Assurance Representative or the Authority
named in the tender or contract.
6.
When NES are incorporated into contracts, users are responsible for their correct
application and for complying with contracts and any other statutory requirements .
Compliance with an NES does not of itself confer immunity from legal obligations .
D313 .94
(ii)
NES 2026
Issue 2
CONTENTS
Page
AUTHORIZATION
(i)
CONDITIONS OF RELEASE
(ii)
CONTENTS
(iii)
INTRODUCTION
(v)
SECTION 1 SCOPE
1
SECTION 2 HEALTH AND SAFETY
1
0201
Warning
Handling Damping Compound Component
Materials
SECTION 3
0202
RELATED DOCUMENTS
1
Table 1 Type 'X' Mount Details
Table 2 Type 'Y' Mount Leaf Spring
Assembly Details
3
4
SECTION 4 DEFINITIONS
5
SECTION I MATERIALS
5
SECTION 6
D313 .94
0502
0503
Stainless Steel
Nylon
Table 3 Immersion Times in Water for Nylon
Components
Damping Compound
Table 4 Composition of Damping Compound
Storage
6
MANUFACTURE
7
Preparation of Metal Surfaces
Assembly Fasteners
Cleaning
Protection of Surfaces 'F and 'G'
Mixing of Components for Damping Compound
Filling of Mount Leaf Spring Assemblies
Curing and Finishing of Filled Mount Leaf
Spring Assemblies
Other Components
III
Clause
0504
6
0510
0602
0606
0608
0609
0610
0615
0618
0621
NES 2026
Issue 2
Page
SECTION 7 INSPECTION AND TESTING
10
Visual Inspection
Force/Compression Tests
SECTION 8
SECTION 9
0701
0702
ACCEPTANCE STANDARDS
11
Table 5 Dimensional and Compression Limits
11
OUALITY ASSURANCE AND
DOCUMENTATION
12
0901
0902
Quality Assurance
Documentation and Certification
SECTION 10 IDENTIFICATION
12
SECTION 11 PACKAGING
13
ANNEX A
PROCUREMENT CHECK-LIST
15
ANNEX B
LIST OF MATERIAL SUPPLIERS
17
ANNEX C
DETERMINATION OF EPOXIDE
EOUIVALENT WEIGHT
19
FASTENERS FOR LEAF SPRING
ASSEMBLIES
21
AIR CONTENT CONTROL TEST FOR
DAMPING COMPOUND
23
ANNEX D
ANNEX E
25
ALPHABETICAL INDEX
D313 .94
Clause
(iv)
NES 2026
Issue 2
INTRODTJCTION
1.
This Naval Engineering Standard (NES) is sponsored by the Procurement Executive,
Ministry of Defence, Director Naval Architecture (DNA) Section NA225 .
2.
If it is found to be unsuitable for any particular requirement the Sponsor is to be informed
in writing with a copy to Director Naval Architecture (DNA) Section NA145 .
3.
Any user of this NES either within MOD or in industry may propose an amendment to it .
Proposals for amendments that are not directly applicable to a particular contract are to be
made to the Sponsor of the NES, and those directly applicable to a particular contract are
to be dealt with as specified in the contract .
4.
No alteration is to be made to this NES except by the issue of an authorized amendment .
5.
Unless otherwise stated, reference in this NES to approval, approved, authorized or similar
terms, means by the Ministry of Defence in writing .
6.
Any significant amendments that may be made to this NES at a later date will be
indicated by a vertical sideline . Deletions will be indicated by 000 appearing at the end of
the line intervals .
7.
Extracts from British Standards within this NES have been included with the permission
of the British Standards Institution .
8.
This NES has been reissued to comply with its five yearly revision programme, to include
changes to Departmental nomenclature, to include testing of the mounts in more detail,
and to ensure that the appropriate service drawings are technically updated with latest
information.
D313 .94
(v)
NES 2026
Issue 2
L
SCOPE
0101 . This NES specifies the requirements to be satisfied in the production and testing of Type
'X' resilient mounts and the leaf spring assemblies of Type 'Y resilient mounts in each of
the eight numbered sizes itemized in Tables 1 and 2 respectively .
0102 . It does not include details for the manufacture of complete Type 'Y' resilient mounts,
which are included in NES 2027 .
2.
HEALTH AND SAFETY
Warning
0201 . This NES calls for the use of processes, substances and/or procedures that may be
in urious to health if adequate precautions are not taken . It refers only to technical
suitability and in no way absolves either the supplier or the user from statutory obligations
relating to health and safety at any stage of manufacture or use . Where attention is drawn
to hazards those quoted may not necessarily be exhaustive .
1' . D ., in
0202 . Before using this NES in connection with the Damping Compound component materials,
users should ma e themselves familiar with the precautionary measures set out in this
Section .
0203 . A suitable barrier cream (for example Kerodex BLV2 or Rozalex No 9) should be used
and gloves (the disposable polyethylene variety is suitable) should be worn for handling
the liquid components called up in this NES even though they do not present severe
dermatitis hazards .
0204 . Care is to be ta en to ensure that the liquid components called up in this NES do not
come into contact with the s in or eyes .
0205 . Aerosil is a finely divided silica dust and its inhalation is to be avoided as far as possible
since it represents a respiratory hazard . For this reason mixing is best carried out under
an extraction hood or in a well ventilated fume cupboard .
0206 . Protective clothing should be wom and other measures ta en as necessary in handling the
materials referred to in this NES .
3.
RELATED DOCUMENTS
0301 . The following documents and publications are referred to in this NES :
See Clause
BS 427
Method for Vic ers hardness test and for
verification of Vic ers hardness testing machines
0502
BS 846
Specification for burettes
Annex C
D313 .94
1
NES 2026
Issue 2
See Clause
BS 1449
Steel plate, sheet and strip
0502
Part 2 : Specification for stainless and heat
resisting steel plate, sheet and strip
BS 3692
Specification for ISO metric precision hexagon
head bolts, screws and nuts . Metric units
(Obsolescent)
Annex D
BS 4183
Specification for machine screws and machine screw
nuts. Metric series
Annex D
BS 4929
Specification for steel hexagon prevailing-torque
type nuts
Part 1 : Metric sizes
BS 5750
Annex D
Quality Systems
Part 1 : Specification for design/development,
production, installation and servicing
0901
Part 2 : Specification for production and installation
0901
BS 6105
Specification for corrosion-resistant stainless
steel fasteners
Annex D
DEF STAN
93-63
Method of specifying polyamide (PA) homopolymers
for moulding and extrusion
0503
NES 723
Requirements for Mar er Plates
1002
NES 2027
Specification for the Type 'Y' Resilient Mount
0622, 1102
0302 . Related drawings for complete Type 'X' mounts and the leaf spring assemblies for Type
'Y' mounts are listed in Tables 1 and 2 respectively . The drawings contain notes and
ma e reference to statements in this NES . The NATO Stoc Numbers refer to the
complete 'X' or 'Y' mounts that is the leaf spring assembly, together with the appropriate
inserts, washers, accelerator units and decelerator components . All related drawings have
been reissued to reflect the contents of this NES .
NES 2026
Issue 2
FOR TYPE X MOUNT :
NATO STOCK NUMBER
SERVICE DRAWING NUMBER
SIZE NUMBER
NOMINAL MASS RATING
1
10 g
5340-99-923-5717
001 005 300 Sheets 1 to 3
001 005 301
001 005 302
001005 303
001 005 304
001 005 305
001 005 306
2
20 g
5340-99-923-5718
001 005 307 Sheets 1 to 3
001 005 303
001 005 305
001005 306
001005 308
001005 309
001 005 310
3
45 g
5340-99-923-5719
001 005 311 Sheets 1 to 3
001 005 312
001005 313
001 005 314
001 005 315
001 005 316
001 005 317
4
70 g
5340-99-923-5720
001
001
001
001
001
001
001
005 318 Sheets I to 3
005 314
005 316
005 317
005 319
005 320
005 321
5
110
g
5340-99-923-5721
001
001
001
001
001
001
001
005 322 Sheets I to 3
005 314
005 316
005 317
005 323
005 324
005 325
6
180
g
5340-99-520-8429
001
001
001
001
001
001
001
001
005 327 Sheets I to 3
005 328
005 329
005 330
005 331
005 332
005 333
005 334
7
320
g
5340-99-520-8428
001 005 335 Sheets 1 to 3
001 005 332
001 005 333
001 005 334
001 005 336
001 005 337
001 005 338
001 005 339
8
450 g
5340-99-520-8427
001
001
001
001
001
001
001
001
TABLE 1 TYPE 'X' MOUNT DETAILS
D313 .94
3
005 341 Sheets I to 3
005 332
005 333
005 334
005 342
005 343
005 344
005 345
NES 2026
Issue 2
FOR TYPE Y MOUNT:
LEAF SPRING ASSEMBLY DETAILS
SIZE NUMBER
NOMINAL MASS RATING
NATO STOCK NUMBER
SERVICE DRAWING NUMBER
1
10 g
5340-99-778-9769
001
001
001
001
008 001 Sheets 1 to 3
005 301
005 302
005 304
2
20 g
5340-99-778-9770
001
001
001
001
001
008
008
005
005
005
3
45 g
5340-99-778-9771
001
001
001
001
001
008 005 Sheets 1 to 3
008 009 Sheet 4
005 312
005 313
005 315
4
70 g
5340-99-778-9772
001
001
001
001
001
001
008
008
008
005
005
005
009 Sheet 4
007 Sheets 1 & 2
005 Sheet 3
319
320
321
5
110
g
5340-99-778-9773
001
001
001
001
008
005
005
005
009 Sheets 1 to 4
323
324
325
6
180
g
5340-99-778-9774
001
001
001
001
001
008 011 Sheets 1 to 4
005 328
005 329
005 330
005 331
7
320
g
5340-99-778-9775
001
001
001
001
001
001
008
008
005
005
005
005
013 Sheets 1 & 2
011 Sheets 3 & 4
336
337
338
339
8
450
g
5340-99-778-9776
001
001
001
001
001
001
008
008
005
005
005
005
015 Sheets I & 2
011 Sheets 3 & 4
342
343
344
345
003 Sheets 1 & 2
001 Sheet 3
308
309
310
TABLE 2 TYPE 'Y' MOUNT LEAF SPRING ASSEMBLY DETAILS
NES 2026
Issue 2
0303. Related documents may be obtained as follows :
a.
British Standards
British Standards Institution, Linford
Wood, Milton Keynes, MK14 6LE
b.
Defence Standards
Directorate of Standardization and
Safety Policy, Stan 1, Kentigern House,
65 Brown St, Glasgow, G2 8EX
c.
Naval Engineering Standards
MOD Library Services (Bath)
d.
Service Drawings
DGFS/ES 921
MOD Library Services (Bath), Foxhill, Bath, BA1 5AB can advise in cases of difficulty .
0304 . All applications to Ministry Establishments for related documents are to quote the relevant
MOD(PE) Invitation to Tender or Contract number and date, together with the sponsoring
Directorate and the Tender or Contract sponsor .
0305 . Prime Contractors are responsible for supplying their subcontractors with relevant
documentation, including specifications and standards .
4.
DEFINITIONS
0401 . For the purpose of this NES, the following definitions apply :
5.
Batch
A quantity made by mixing in a given container at one time
Nominal Mass
The nominal mass the mount is designed to support
Nominal Force
The force applied by the nominal mass
MATERIALS
0501 . The materials for construction of the 'X' mounts and leaf spring assemblies for the 'Y'
mounts are to be as stated in this NES and the drawings listed in Tables 1 and 2 . In the
event of any discrepancy between this NES and the appropriate drawing the NES is to
ta e precedence .
Stainless Steel
0502 . The stainless steel for the mount leaf springs, face plates, and inner washers is to be grade
304S31 to BS 1449 Part 2 and to the Vic ers Hardness specified on the appropriate
drawing. Vic ers Hardness measurements are to be carried out in accordance with
BS 427.
NES 2026
Issue 2
Nylon
0503. The material of the inserts and outer washers referred to on the appropriate drawings is to
be Nylon (Polyamide material to Def Stan 93-63/1 - PA66, MNS, 14-030, 01) with an
additional moisture stabilization treatment as follows :
a.
The nylon components are to be immersed in water at either 70 °C - 75°C or
80°C - 85°C for the times given in Table 3 . It is acceptable to use an
accumulated time at these elevated temperatures provided the components remain
immersed between heating cycles .
TIME AT 70°C - 75 ° C
hrs (MINIMUM)
TIME AT 80°C - 85 ° C
hrs (MINIMUM)
35
25
Inserts for 180, 320 and 450 g
mounts, and outer washers for 10,
20, 45, 70 and 110 g mounts
150
70
Outer washers for 180, 320 and
450 g mounts
260
110
COMPONENTS
Inserts for 10, 20, 45, 70 and
110 g mounts
TABLE 3 IMMERSION TIMES IN WATER FOR NYLON COMPONENTS
b.
After sha ing off excess water the components are to be stored in sealed
polyethylene sac s at 42°± 2°C for at least one wee .
c.
Thereafter the components are to be stored at 18 - 15°C in sealed polyethylene
sac s .
Damping Compound
0504 . The composition of the damping compound is to be Compound 'A' or Compound 'B' as
defined in Table 4, and Clauses 0505 - 0509 . Details of the mixing procedure are given
in Section 6 and material suppliers in Annex B .
COMPONENT
COMPOUND 'A' FOR MOUNT
SIZES 1 and 2
COMPOUND 'B' FOR MOUNT
SIZES 3, 4, 5, 6, 7 & 8
100.0 parts by weight
100.0 parts by weight
Flexibilizer
90.0 parts by weight
85.0 parts by weight
Hardener
17.5 parts by weight
20.0 parts by weight
Aerosil Filler
10.9 parts by weight
Resin component
China Clay Filler
nil
nil
137.0 parts by weight
TABLE 4 COMPOSITION OF DAMPING COMPOUND
D313 .94
6
NES 2026
Issue 2
0505. The resin component is - to consist of a liquid bisphenol 'A' difunctional epoxide resin of
epoxide equivalent weight within the range 170 to 190 grammes as determined in
accordance with Annex C . The following resins conform to this requirement and are to be
selected for use :
a.
Epidote 828 supplied by Shell Chemicals (UK) Ltd .
b.
Epophen EL-5 supplied by Borden Chemical Co (UK) Ltd .
c.
Epoxide Resin DER 331 supplied by Dow Chemical Co Ltd .
d.
Araldite MY750 supplied by CIBA-Geigy Polymers .
0506 . The flexibilizer component is to be NN 1 Dicyano Ethylated Aliphatic Diamine plus low
molecular weight Aliphatic Amines in the form of HMD Compound, supplied by Contract
Chemicals (Knowsley) Ltd . No other material is to be used.
0507 . The hardener component is to be a polyamide resin, Synolide 960, supplied by Cray
Valley Ltd .
0508 . For Type 'X' mounts and Type 'Y' mount leaf spring assemblies with size numbers 1 or 2
the filler component is to consist of Aerosil (Standard uncompressed grade), supplied by
Degussa Ltd.
0509 . For Type 'X' mounts and Type 'Y' mount leaf spring assemblies with Size Numbers 3, 4,
5, 6, 7 or 8 the filler component is to consist of China Clay, dried and dressed having a
pH value of 5.3, supplied by Whitfield Chemicals Ltd .
Storage
0510 . The resin, flexibilizer and hardener components are to be stored at a temperature between
18°C and 25°C. The filler is to be stored in a dry place .
0511 . If the temperature of the flexibilizer compound should fall below 18°C such that the
compound subsequently crystallizes, the compound is to be warmed gently in an air
circulation oven set at approximately 30 °C, the drum rolled to ensure uniformity of
contents, and then cooled to between 18°C and 25 °C before use .
6.
MANUFACTURE
0601 . Each mount Leaf Spring Assembly is to be manufactured in accordance with this NES and
the appropriate drawings . In the event of any discrepancy between this NES and the
appropriate drawing the NES is to ta e precedence.
Preparation of Metal Surfaces
0602 . The edges of the leaves are to be rounded to remove sharp edges and/or burrs . Burrs on
the edges of holes are to be removed .
D313 .94
7
NES 2026
Issue 2
0603 . The steel surfaces are to be free of contaminants in all stages of manufacture and
assembly in order to obtain a bond between the damping compound and the steel surfaces .
The surfaces of the leaves are to be abraded to ensure a ey between the steel and the
damping compound . The method of abrasion is to be grit blasting applied to the leaves
before assembly, using alumina grit of 40 - 80 grit size .
0604 . For Type 'Y' Mount leaf spring assemblies with Size Numbers 1 or 2 the face plates
providing Surfaces F and 'G' identified on the appropriate drawing, are to be grit blasted
or sub ected to an alternative abrading process before assembly .
0605 . For Type 'Y' mount leaf spring assemblies with the face plates Size Numbers 3 to 8
providing Surfaces F and 'G' identified on the appropriate drawing are to be treated as
follows :
a.
Surface 'G' is to be grit blasted or sub ected to an alternative abrading process
before assembly.
b.
Surface 'F is to be lightly ground if necessary after assembly of the leaf spring unit
to provide a flat and abraded surface for later attachment of the accelerator unit .
Assembly Fasteners
0606 . When assembling the Leaf Spring units the leaves and face plates are to be fastened
together by rivets, bolts or screws as shown on the Leaf Spring Assembly drawings .
Details of the rivets, bolts, screws and nuts to be used are given in Annex D, and the
supplier of the rivets is given in Annex B .
0607. In Leaf Spring Assemblies where pop rivets are used the bro en stems of the rivets are to
be removed after assembly . In Leaf Spring Assemblies when bolts or screws are used the
self loc ing nuts are to be tightened up on assembly to 6 .0 nm maximum torque .
Cleaning
0608 . Before filling with damping compound each mount leaf spring assembly is to be
thoroughly degreased using acetone, dichloromethane or an alternative degreasant and
allowed to dry . Care is to be ta en to avoid the presence of condensation on surfaces
caused by the cooling effect of evaporating degreasing agent .
Protection of Surfaces F and 'G'
0609 . After cleaning but before mar ing, or filling of each Leaf Spring Assembly for Type 'Y'
mounts, Surfaces F and 'G' may be protected by a suitable, easily removed covering to
avoid contamination of the surfaces .
U
. 1' 1
1 11 a I 1' I
1
0 .110 1'
1 R 9 1 . 1 S
0610 . All components for the damping compound are to be weighed to within a tolerance of ±
2% on each specified amount . The components are to be at a temperature between 18°C
and 25°C before mixing .
D313.94
8
NES 2026
Issue 2
0611 . The material is to be prepared in a planetary type mixer (eg Be en Planatex, Hobart or
Kenwood Mixers). The components are to be mixed in the order shown in Table 4,
starting with the resin component and each component is to be thoroughly blended into the
mix before another is added . Care is to be ta en to ensure that the compound is
thoroughly mixed. Mixing is to be stopped at frequent intervals and the mixture scraped
from the sides of the bowl into the centre of the mix with the main mass of mixture . At
the end of the mixing process no partly mixed compound or scrapings of mix are to be
added to the main bul of the mixed compound .
CAUTION :
It is essential that the above is followed otherwise local seepage problems
may occur at a later date.
0612. To ensure that the mount filled with damping compound has the necessary stiffness, the
air content of the cured compound in the mount is to be controlled to not less than 20%
by volume . This can be achieved by carrying air into the mix by prolonged mixing
especially at higher speeds . Mixing is to be continued until the specific gravity of the
aerated compound is 0 .78 or less for compound 'A' and 0 .98 or less for compound 'B' as
determined by the method detailed in Annex E . As a guide, a preliminary mixing period
of approximately 10 minutes is suggested before carrying out an air content control test.
0613 . The quantity of damping compound that can be mixed in one batch is limited by the pot
life of the material, which is dependent upon both its bul and the ambient temperature . It
has been found that a 2 g to 5 g batch has a pot life of about three to four hours after
mixing when ept at a temperature of between 18° and 25 °C.
0614 . Once cured, this mix is difficult to remove with solvents, although dichloromethane
(methylene chloride) will attac the material slowly . The individual liquid components
and the UNCURED mix are readily soluble in etone solvents .
Filling of Mount Leaf Spring Assemblies
0615 . Before filling commences, one side of the mount leaf spring assembly is to be sealed off
with tape or other means and the mount leaf spring assembly is to be placed on its side .
0616 . The spaces between the leaves of each mount leaf spring assembly are to be completely
filled with the damping compound formulated and mixed in accordance with the
requirements stated in Clauses 0610 - 0613 . Filling is to ta e place at an ambient
temperature between 18°C and 25 °C. The mix is to be introduced into the cavities
between the leaves without forming any air poc ets . The cavities should be slightly
overfilled to produce a convex meniscus .
0617 . After filling, the compound tends to settle and shrin away from the edges of the leaf
springs . The shrin age is to be made good as necessary within three hours of the first
filling by using material from the same damping compound mix . Further topping up may
be carried out as necessary after 24 - 32 hours but this must be with damping compound
mix from a different batch.
NES 2026
Issue 2
Curing and Finishing of Filled Mount Leaf Spring Assemblies
0618 . After filling, the mount leaf spring assemblies are to be ept at a temperature between
18° C and 25 °C for an initial curing period of 72 hours minimum (continuous) and then
sub ected to a final curing period of 48 hours minimum (continuous) at a temperature of
42°C ± 2°C.
0619 . After curing the damping compound is to be levelled as necessary by trimming . A dusting
of french chal may be necessary to reduce the slight surface tac iness .
0620 . When finishing the leaf spring assemblies no coating is to be carried out but all the
exposed leaf spring surfaces are to be free of cured damping compound .
Other Components
0621 . On completion of each 'X' mount the nylon inserts, nylon outer washers and stainless steel
inner washers are to be held together as sets by means of a cord or tie .
0622 . On completion of each leaf spring assembly for 'Y' mounts the nylon insert, nylon outer
washer, stainless steel inner washer, accelerator units, and rubber decelerator are to be
assembled in accordance with NES 2027 .
7.
INSPECTION AND TESTING
Visual Inspection
0701 . Each Type 'X' and Type 'Y' mount leaf spring assembly is to be visually inspected . In the
event of unsatisfactory units see Clauses 0803-0804 .
Force/Compression Tests
0702 . Force/compression tests are to be carried out on at least one mount or leaf spring assembly
of a given size from a manufacturing batch, that is made of leaf springs from the same
batches of material and filled with the same batch of mixed damping compound . The
number to be tested is to be 1, 2, 3 or 1 in every 40 from batches of given size items of
1 - 10, 11 - 50, 51 - 120 and greater than 120 respectively. The test details are to be as
follows :
a.
The force is to be applied to the vertical axis of the mounting or leaf spring
assembly by a machine at a compression rate of between 10 mm and 15 mm per
minute and capable of delivering 1 .5 times the nominal force . All compression and
release of forces referred to in Clauses b to f are to be carried out within the rates
given above .
b.
The mounting or leaf spring assembly is to be conditioned at 20°C ± 2°C for at
least 24 hours prior to testing . Testing is to be carried out at a temperature of
20°C ± 2°C.
c.
The height of the mounting or leaf spring assembly is to be measured and recorded
as the initial height .
D313 .94
10
NES 2026
Issue 2
d.
The filled mounting or leaf spring assembly is to be compressed in its vertical axis
to 1 .5 times its nominal force with zero dwell and then the force released to zero
force. This operation is to be carried out four times . The deflection gauge is then
to be ad usted to zero for zero force and the nominal force applied to the filled
mounting or leaf spring assembly . This force must be maintained for four minutes,
then the compression is to be noted . This value is to be recorded as the
compression 6 under nominal force .
e.
The force is to be released and the mounting or leaf spring assembly allowed to
stand for two minutes before again measuring the height of the mounting or leaf
spring assembly . This height is to be recorded as the recovered height .
f.
The initial height minus the recovered height is to be recorded as the permanent set
of the mounting or leaf spring assembly .
0703 . Before pac aging and despatch each 'X' mount is to be visually inspected to ensure that
the required stainless steel inner washers, nylon inserts, and nylon outer washers are held
together as in Clause 0621 .
8.
ACCEPTANCE STANDARDS
0801 . On visual inspection of both sides of the leaf spring assembly (see Clause 0701) the
damping compound must completely fill the spaces between the leaves . Any meniscus
must start from the edges of the leaf springs . The damping compound must not show
signs of exuding from between the leaves .
0802 . On force/compression testing (see Clause 0702) the dimensional and compression results
for the filled 'X' mounts and the filled leaf spring assemblies for the 'Y' mounts are to
comply with Table 5 .
MOUNT OR
LEAF SPRING
RATING
LIMITS OF
INITIAL 'X'
MOUNT HEIGHT
LIMITS OF INITIAL
Y MOUNT LEAF
SPRING ASSEMBLY
HEIGHT
LIMITS OF
COMPRESSION 6
UNDER NOMINAL
FORCE
PERMANENT
SET
mm
mm
mm
mm
10
95 .3±1 .3
95 .3 ± 1 .3
5.0 ± 1.3
<0 .76
20
95 .3 ± 1 .3
95 .3 ± 1 .3
6 .7+ 1 .7
<0.76
45
114 .3±1 .3
114 .8 ± 1 .3
8.2±2 .1
<1 .2
70
114.3±1 .3
114.6±1 .3
8 .3±2 .1
<1 .2
110
114 .3±1 .3
114 .3±1 .3
10 .4±2 .6
<1 .2
180
165 .1±0 .8
166.8±0 .8
5 .1±1 .3
<1 .6
320
165 .1 ± 0.8
166.5 ± 0.8
5 .8 ± 1 .5
<2.0
450
165 .1±0 .8
166.2±0 .8
6.4±1 .6
<2.5
g
TABLE 5 DIMENSIONAL AND COMPRESSION LIMITS
D313 .94
11
NES 2026
Issue 2
0803 . The following courses of action are to be ta en in the event of the requirements of
Clauses 0801 - 0802 not being met .
a.
Failure to meet the requirements of Clause 0801 - each individual mount or leaf
spring assembly is to be re ected .
b.
Failure to meet the requirements of Clause 0802 - test a further mount or leaf
spring assembly. If this one fails to meet the requirements then all the mounts or
leaf spring assemblies of a given size filled with the same batch of damping
compound are to be re ected .
0804 . The metal components from any re ected or rewor ed mount or leaf spring assembly may
be reused provided that :
9.
a.
removal of the damping compound has not damaged any of the metal components ;
b.
all nylon components or components containing nylon have been replaced by new ;
c.
after manufacture the resulting batch of rewor ed finished mounts or leaf spring
assemblies are reinspected and retested in accordance with Section 7 .
QUALITY ASSURANCE AND DOCUMENTATION
Quality Assurance
0901 . The manufacturer is to maintain QA systems and procedures in accordance with BS 5750
Part 1 (ISO 9001) or BS 5750 Part 2 (ISO 9002) as specified in the Procurement
Specification . Procedures and documentation are to be such as to ensure full material
traceability, and are to be retained by the contractor for five years ; MOD approval is to be
obtained prior to disposal .
Documentation and Certification
0902. Each order quantity of each size of Type 'X' mounts or Type 'Y' mount leaf spring
assemblies is to be accompanied by full Quality Assurance Documentation appropriate to
the respective manufacturing batches giving the actual results of all the tests required by
Section 7 together with a Certificate of Conformity with the relevant Acceptance
Standards detailed in Section 8 . An additional copy of the actual results of the tests is to
be sent to DNA Section NA225 . Test records are to identify the mounts or leaf spring
assemblies by the serial numbers.
10.
IDENTIFICATION
1001 . Each mount or leaf spring assembly is to be mar ed at the position 'E' shown on the
appropriate drawing to record the following information :
Manufacturer's name ;
Manufacturer's serial number (see Clause 1103) ;
Mount identification (Type 'X' or Type 'Y') ;
Mount Nominal Mass Rating ;
D313 .94
12
NES 2026
Issue 2
Month and year of manufacture ;
NATO Stoc Number (as defined in Tables 1 and 2)
1002 . The method of achieving the mar ing is to be by means of a self adhesive mar er, which
is to be in accordance with NES 723 .
1003 . The manufacturer's serial number is to be such that for each mount or leaf spring assembly
the batch of damping compound used to fill it can be identified .
1004 . The Nominal Mass Rating (numerals only) for each mount or leaf spring assembly is to be
mar ed on faces A, B, C and D as indicated on the appropriate drawing using a white
lacquer based on Chlorosulphonated Polyethylene, for example Hypalon Lacquer Type PL
71 supplied by FPT Ltd, whose address is given in Annex B . The letters are to be a
minimum of 15 mm high and the depth of shading such they provide a high degree of
contrast on the leaf spring surface .
11.
PACKAGING
1101 . The 'X' mounts are to be individually pac aged such that the leaf spring assembly and its
associated components are contained within a single sealed pac age. The pac aging is to
be clearly and legibly mar ed in addition to any statutory requirements with the following
information:
NATO Stoc Number ;
Date of Manufacture ;
Type of Mount and Size Number ;
Mount Serial Number ;
Date of Despatch ;
Manufacturers Name or Trademar ;
MOD Form 640 Reference Number ;
1102 . The pac aging of the 'Y' mounts is to be in accordance with NES 2027 .
D313 .94
13
NES 2026
Issue 2
D313 .94
14
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Issue 2
PROCUREMENT CHECK-LIST
Notes :
1.
This Chec List is to ensure that certain aspects *of this Naval Engineering
Standard are consulted when preparing a Statement of Technical Requirements
for a particular application .
2.
Clauses where a preference for an option is to be used or where specific data
is to be added are included in the Chec List .
3.
Each item is to be mar ed either:
1
NA
Chec
No
=
=
Included
Not applicable
Chec
Clause No
1
That the type of mount and size is
specified
0302
Tables 1 and 2
2
That the manufacturing process is
specified
0601- 0622
3
That the Inspection and Testing
requirements are specified
Sections 7 and 8
4
That Contractor's Quality Assistance
systems and procedures are in
accordance with BS 5750 Part 1 and 2
0901
5
That MOD approval is sought prior to
disposal of any QA documentation
0901
6
That Identification and Pac aging
requirements are specified
Sections 10 and
11
D313 .94
15
l or NA
ANNEX A
NES 2026
Issue 2
ANNEX A
D313 .94
16
LIST OF MATERIAL SUPPLIERS
Borden Chemical Co (UK) Ltd
North Baddesley
Rownhams Road
Southampton
S052 9ZB
Dow Chemical Co Ltd
La eside House
Stoc ley Par
Uxbridge
Middlesex
UB11 1BE
CIBA-Geigy Polymers
Duxford
Cambridge
CB2 4QA
FPT Ltd
The Airport
Portsmouth Hampshire
PD3 5PE
Contract Chemicals (Knowsley) Ltd
Penrhyn Road
Knowsley Industrial Par
Prescot
Merseyside
L34 9HY
Shell Chemicals (UK) Ltd
Heronbridge House
Chester Business Par
Chester
CH4 9QA
Cray Valley Ltd
Waterloo Wor s
Machen
Near Newport
Gwent
NP1 8YN
Tuc er Fasteners Ltd
Walsall Road
Birmingham
B42 1BP
Degussa Ltd
Paul Ungerer House
Earl Road
Stanley Green
Handford
Wilmslow
Cheshire
SK9 3RL
Whitefield Chemicals Ltd
23 Albert Street
Newcastle-under-Lyme
Staffordshire
ST5 1JP
D313 .94
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Issue 2
ANNEX B
D313 .94
18
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Issue 2
DETERMINATION OF EPOXIDE EOUIVALENT WEIGHT
Summary
C1.
In the presence of glacial acetic acid, hydrogen bromide reacts quantitatively with oxirane
oxygen . The end-point is clearly shown with crystal violet .
Reagents
C2 .
Sodium carbonate, anhydrous, dried by heating at 160 °C.
Chlorobenzene .
Crystal violet indicator . 0.1% w/v in glacial acetic acid .
Note : All reagents are to be of recognized analytical reagent quality and distilled water is
to be used wherever water is specified .
C3.
To produce 0 .1N Hydrogen bromide : Add 8 ml of hydrogen bromide, 50% w/v in acetic
acid, to 500 ml of glacial acetic acid and thoroughly mix to give an approximately 0 .1N
solution . This solution is not very stable and requires restandardizing if more than 24
hours have elapsed since the last standardization .
C4.
The hydrogen bromide solution is hygroscopic and the titration should be carried out in a
closed system; burettes in accordance with BS 846, are suitable .
C5.
Standardize as follows :
Weight accurately approximately 0 .05 g anhydrous sodium carbonate into a flas and
dissolve in 10 ml glacial acid . Add five drops of crystal violet . Attach to the burette
which has been freshly filled with 0 .1N hydrogen bromide . Titrate with stirring to a
degree end-point .
If X g of sodium carbonate are ta en and Y ml of reagent are required, then normality A
is:
A=
X x 18.87
Y
Procedure
C6.
Weight accurately into a dry flas 0.1 to 0 .2 g of epoxide resin (the actual amount
depends on the expected epoxide equivalent) . Add 10 ml of chlorobenzene and dissolve
the resin with gentle heating if necessary . Cool the flas to room temperature and add
five drops of crystal violet indicator. Titrate the solution to the same end-point as in the
standardization of the reagent .
Epoxide equivalent weight =
D313 .94
W x 1000 grammes
19
ANNEX C
NES 2026
Issue 2
When A = normality of hydrogen bromide solution
W = weight of resin
T = ml of reagent used
Note : The titration is almost instantaneous with glycidyl ethers, but with cycloaliphatic
epoxides the reaction is much slower and it may ta e up to 15 minutes to reach a
permanent end-point .
ANNEX C
D313.94
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FASTENERS FOR LEAF SPRING ASSEMBLIES
MOUNT SIZE
NUMBER
MOUNT NOMINAL
MASS RATING
1 & 2
10 g & 20 g
3,4 & 5
45 g, 70 g & 110
g
6,7 & 8
180 g, 320 g &
450 g
DETAILS OF FASTENERS FOR LEAF
SPRING ASSEMBLY
Monel metal dome headed pop rivets 4.8 mm
diameter, type LUD/650/BS/002 as manufactured
by Tuc er Fasteners Ltd, or equivalent .
Monel pop rivets 6 .4 mm diameter, dome headed
or countersun headed as indicated on the
appropriate leaf spring assembly drawing .
Rivets, type LUD/870/BS/002 or LUD/870/GS/002
dome headed ; type LUK/870/BS/002 or
LUK/870/GS/002 countersun headed; as
manufactured by Tuc er Fasteners Ltd, or .
equivalent
Bolts or screws and nuts as indicated on the
appropriate leaf spring assembly drawing .
Bolts: M8 ISO metric coarse to BS 3692,
Machine Precision Hexagon Head, Stainless Steel
to BS 6105 A4-880 Austenitic . 30 mm long.
Screws : M8 ISO metric coarse, Slotted
Countersun Head, Machine Screw to BS 4183 .
Stainless Steel to BS 6105 A4-80 Austenitic
30 mm long .
Nuts : M8 ISO metric coarse to BS 3692,
Hexagon, Nylon Insert Self Loc ing or all metal
Self Loc ing to BS 4929 Part 1 Property Class 8 .
Stainless Steel to BS 6105 A4-80 Austenitic .
D313 .94
21
ANNEX D
NES 2026
Issue 2
ANNEX D
D313 .94
22
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Issue 2
. 0
ND
Summary
El .
This test is based on the following expression which relates the mass of a nown volume
of compound in a container to that specific gravity which corresponds to a minimum
acceptable air content :
-Mmax :M_
0.78 maximum for compound 'A' and
Specific Gravity =
V
0.98 maximum for compound 'B'
=
Mmax
It follows that
and
M
0.98 V + m for compound 'B'
max
Where :
0.78 V + m for compound 'A'
Mmax is the maximum acceptable mass of the filled container in grammes .
m
is the mass of the empty container in grammes .
V
is the volume of the container in ml .
The value of the specific gravity is to be 0 .78 or less for compound 'A' and
0.98 or less for compound 'B' to give greater than 20% v/v air content in
the final products .
Procedure
E2 .
A lipless bea er or similar container with a level top of capacity 300 to 500 ml or a
specific gravity cup is weighed . The container is then filled to the brim with water and
re-weighed . The difference between the two mass values in grammes is ta en as equal to
the volume of the container in ml .
E3.
After the preliminary mixing period the container is filled completely with a sample of the
mix, any excess being removed from the top with a nife/straight edge . The filled
container is weighed and if the filled container mass is not greater than M
grammes
then the mixing is complete. If, however, the filled container mass exceed
grammes then the mixing process must be continued and the sampling process repeated
until the condition specified in Paragraph El for the specific gravity of the damping
compound is fulfilled .
E4 .
All measurements are to be accurate within ± 2% .
D313 .94
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ANNEX E
NES 2026
Issue 2
ANNEX E
D313 .94
24
ALPHABETICAL INDEX
Acceptance Standards
Force/Compression Tests 0802
Visual Inspection 0801
Certificate of Conformity 0902
Curing 0618, 0619
Damping Compound 0205, 0504
Fasteners 0606, 0607, Annex D
Filler (China Clay) 0504, 0509
Filler (Aerosil) 0205, 0504, 0508
Filling 0615-0617
Flexibilizer 0504, 0506
Hardener 0504, 0507
Health and Safety 0201-0206
Identification 1001-1004
Leaf Spring Assembly 0302, 0501, 0601
Mixing 0610-0613
Nylon 0503
Pac aging 1101, 1102
Preparation of Surfaces 0602-0605
D313 .94
25.
NES 2026
Issue 2
Quality Assurance Documentation 0902
Quality Assurance System 0901
Re ection 0803
Resin 0504, 0505
Retesting 0804
Rewor ing 0804
Service drawings Table 1, Table 2
Stainless steel 0502, Annex D
Storage 0510-0511
Testing
Force/compression test 0702
Visual inspection 0701, 0801
'X' Mounts
0302, 0501, 0621, Table 1
'Y' Mounts 0302, 0501, 0622, Table 2
D313.94
26.
Inside Rear Cover
© Crown Copyright 2000
Copying Only as Agreed with DStan
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Defence Procurement Agency
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Fax 0141 224 2503
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The DStan file reference relating to wor on this standard is D/DStan/069/22/26 .
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