Note: Descriptions are shown in the official language in which they were submitted.
CA 02794673 2012-11-02
Load-Relief Washer for Threaded Fasteners Therefor
The present invention relates to a load-relief washer for threaded fasteners.
More
specifically, the present invention relates to the use of a multiple part
washer with
complimentary stepped or castellated features to selectively eliminate the
tensile load in a bolt or
stud.
BACKGROUND OF THE INVENTION
Galling is a common complication that arises when fastening or disassembling
threaded
components. Galling can result in damage to the threaded features or seizing
of said components.
Such damage or seizing can often be costly to repair or remedy. Galling is a
form of adhesive
wear and material transfer between metallic surfaces during operations in
which relative motion
of said surfaces is involved. The fastening of threaded components, in which
interlocking
threaded features are slid past each other under high loads, is an industrial
operation which is
notably prone or vulnerable to galling. Galling is a major concern in said
application because the
same features which promote galling, such as material ductility, metal on
metal contact, friction,
and high compressive loads, are not only present, but are indeed necessary
features for operation.
However, galling can also occur at relatively low loads since localized
pressure and
energy density are greater than their respective macroscopic values. It is
these local values which
can result in elevated friction, promote material transfer, and induce phase
transition. When two
metallic surfaces, such as complimentary screw threads, are forced together,
the high points or
asperities found on each surface are the initial mating points. It is possible
for said asperities to
1
CA 02794673 2012-11-02
penetrate the opposing surface upon application of relative movement, thereby
initiating plastic
deformation and frictional forces between said surfaces. The induced pressure
is highly
localized, and the small region upon which the pressure is applied is termed
the contact zone.
Said pressure elevation yields increased friction heating and adhesive forces,
thereby resulting in
initiation of material transfer, creation of additional protrusions, and
growth of said protrusions.
Furthermore, galling is especially likely when disassembling threaded
fasteners which have been
in service for several years due to additional debris from local oxidation,
foreign contaminants,
and the breakdown, seepage, and removal of assembly lubricants.
The high ductility of commonly used machine screws can be considered a
requisite
characteristic for substantial material transfer and galling. Frictional
heating is greatly related to
the size, shape, and material properties of the plastic zones that surround
the penetrating objects.
Correspondingly, brittle fractures rarely generate copious amounts of heat due
to the small,
transitory plastic zones. If the height of the protrusion grows larger than a
critical threshold
value, it may penetrate the brittle oxide layer of the complimentary mating
surface. As a result,
said protrusion could cause damage to the ductile bulk material on which the
oxide layer
originally formed, thus creating a region of plastic flow around said
protrusion. Thus, the
geometry, loading conditions, and relative motion of the protrusion govern the
material flow,
contact pressure, and thermal profile during sliding.
In the dynamic sliding contact of nut torqueing, increasing axial compressive
force is
proportionally equal to a rise in potential energy and thermal energy in the
aforementioned
localized system. Thus, the high loads and relative rotation associated with
the torqueing of
threaded nuts onto and off of threaded counterparts are particularly
susceptible to galling.
Additionally, as the nut is turned further and sliding progresses, additional
energy is supplied to
2
CA 02794673 2012-11-02
the system. Initially, there is limited energy loss in the system (contact
zone), since heat
conduction away from the contact zone is significantly inhibited by the
relatively small cross
sectional area for thermal transport, and correspondingly low conductance, on
the system
boundary. The result is a corresponding increase in energy density and
temperature in the contact
zone, and said energy accumulation can damage the contact surfaces and alter
their plastic
behavior. Furthermore, the combination of direct contact and plastically
deforming flow fields
can result in the constitution of a common plastic zone in which the high
energy density,
pressure, and temperature promote inter-surface bonding. Generally, this
greatly increases
apparent adhesion as well as the force needed for further nut advancement or
removal. In some
cases this can cause seizing of the nut onto the threaded component, and
removal of said nut
requires time-consuming or destructive techniques such as cutting of the nut
or screw. Reducing
or eliminating the compressive load between threads greatly reduces the
likelihood of galling due
to a decrease in localized potential energy and frictional heating in the
system.
One possible method of galling prevention is the use of a tensioning system to
stretch the
bolt before turning the nut off. Examples of such tensioning systems include
hydraulic bolt
tensioners and hydraulic nuts. However, the use of such systems can be time
intensive and often
require additional hydraulic machinery to produce the requisite operating
pressures. Furthermore,
said tensioning methods involve temporarily increasing the compressive load on
the bolted
component during disassembly, which may be undesirable in some circumstances.
Examples of
hydraulic tensioning devices can be found in United States patent numbers
4,998,453;
5,527,015; and 7,673,849.
Another possible method of galling prevention is the use of a plurality of
jackbolts to
mechanically tension and unload the main stud or bolt. Contrary to the
previously described
3
CA 02794673 2015-09-28
hydraulic tensioning systems, this method has the advantage of not
necessitating an
increase of the compressive load on the bolted components during disassembly.
However,
this method of disassembly can be time intensive since multiple jackbolts must
be
unloaded for each main stud, often employing an iterative, step-wise unloading
scheme.
Examples of multiple jackbolt devices can be found in United States patent
numbers
3,618,994; 4,338,037; and 4,622,730.
An additional method of galling prevention is through the use of non-standard
bolts or nuts. For example, United States patent number 8,206,072 describes a
quick
release nut which may be selectively disengaged from the fasteners threads.
However, it
is often necessary to employ standardized fasteners in order to comply with
industry
guidelines. Thus, the use of a specialty quick-release nut may be undesirable.
There is therefore a need for a load-relief washer which obviates the
aforementioned problems.
OBJECTS OF THE INVENTION
The present invention is directed to a load relief washer assembly for
associated
fasteners. The load relief washer assembly comprises:
a first body having a substantially annular shape with a through hole for an
associated bolt or stud or threaded fastener to pass, and having a top surface
and
bottom surface, wherein the top surface has a plurality of stepped features or
castellated features which form mating surfaces and a plurality of sliding
planes;
a second body having a substantially annular shape with a through hole for the
associated bolt or stud or threaded fastener to pass, and having a top surface
and
bottom surface, wherein the bottom surface has a plurality of stepped features
or
castellated features which form mating surfaces and a plurality of sliding
planes;
wherein the stepped features or castellated features and the sliding planes of
the first body and second body are complementary to one another; and
whereby, in use, when the load relief washer is assembled with the associated
bolt, stud, or threaded fastener, the first body may be rotated relative to
the second
4
CA 02794673 2015-09-28
body along the sliding planes, the stepped features or castellated features of
the first body and the second body align allowing the first body and the
second
body to move toward one another which reduces an overall height of the load
relief washer assembly; thereby reducing a tensile load to the associated
bolt, stud,
or threaded fastener.
According to a preferred embodiment, the first body and the second body may
each include four of the stepped features or castellated features and
plurality of sliding
planes.
According to a preferred embodiment, the first body and the second body may
each include eight of the stepped features or castellated features and a
plurality of sliding
planes.
According to a preferred embodiment, the substantially annular shape first
body
may be dodecagonal.
According to a preferred embodiment, the substantially annular shape first
body
may further comprise splines along an outer perimeter to assist with rotating
the first
body relative to the second body.
According to a preferred embodiment, the substantially annular shape first
body
may further comprise a plurality of transverse holes.
According to a preferred embodiment, the first body may further comprise a
geometric feature on the surface opposite the surface having the stepped
feature or
castellated feature to aid in or inhibit rotation of the first body.
According to a preferred embodiment, the second body may further comprise a
geometric feature on the surface opposite the surface having the stepped
feature or
castellated feature to aid in or inhibit rotation of the second body.
According to a preferred embodiment, the first body may further comprise a
surface finish on the surface opposite the surface having the stepped feature
or castellated
feature to aid in or inhibit rotation of the first body.
4a
CA 02794673 2015-09-28
According to a preferred embodiment, the second body may further comprise a
surface finish on the surface opposite the surface having the stepped feature
or castellated
feature to aid in or inhibit rotation of the second body.
The invention is also directed to a method to activate a load relief washer
assembly as defined herein, when a load relief washer is assembled with an
associated
bolt, stud, or threaded fastener. The method comprises the steps of:
a) aligning the stepped features or castellated features of the first body and
the
second body by rotating the first body relatively to the second body along the
sliding planes; and
b) allowing the first body and the second body to move toward one another for
reducing the overall height of the load relief washer assembly thereby
reducing
the tensile load to the associated bolt, stud, or threaded fastener.
The invention is also directed to the use of the load washer assembly as
defined herein,
when a load relief washer is assembled with an associated bolt, stud, or
threaded fastener
for reducing the tensile load to the associated bolt, stud, or threaded
fastener.
Accordingly, an object of this invention is the prevention of galling threaded
features during the disassembly of bolted assemblies by reducing the load on
said
threaded features prior to disassembly.
Another object of this invention is the reduction of the load on the
aforementioned
threaded features without a corresponding increase of the axial tensile bolt
load.
An additional object of the invention is to increase the speed of disassembly
of
bolted assemblies by eliminating the need for hydraulic machinery and the slow
process
of tensioning.
An additional object of the invention is to allow the use of industry standard
threaded
4b
CA 02794673 2012-11-02
fasteners such as threaded rods, bolts, studs, or nuts.
Another object of the invention is to increase the speed of the unloading
process of bolted
assemblies by requiring only a partial rotation of one part of the washer to
remove the bolt load.
Other objects and advantages of the present invention will become obvious to
the reader
upon an understanding of the illustrative embodiments about to be described or
will be indicated
in the claims, and various advantages not referred to herein will occur to one
skilled in the art
upon employment of the invention in practice.
BRIEF SUMMARY OF THE INVENTION
To attain these and other objects which will become more apparent as the
description
proceeds according to one aspect of the present invention, there is provided a
load-relief washer
for threaded fasteners.
More specifically, in accordance with the present invention, there is provided
a load relief
washer assembly for threaded fasteners (FIGS. 1 to 13) comprising a lower
washer piece (1), an
upper washer piece (2), a plurality of complimentary stepped features (4)
which comprise the
mating surfaces of the lower washer (1) and the upper washer (2), and a
plurality of sliding
planes (3) created by the interface of the lower washer (1) and the upper
washer (2). The lower
washer (1) and the upper washer (2) each include a hole (5) in their body
through which a main
bolt or stud may pass.
There is also provided a load relief washer assembly (FIGS. 14 to 19) combined
with a
threaded bolt (9) with an integrated bolt head (7) and a threaded nut (8) to
clamp two work
CA 02794673 2012-11-02
pieces (6) together. The load relief washer assembly comprises a lower washer
piece (1), an
upper washer piece (2), a plurality of complimentary stepped features (4)
which comprise the
mating surfaces of the lower washer (1) and the upper washer (2), and a
plurality of sliding
planes (3) created by the interface of the lower washer (1) and the upper
washer (2). The lower
washer (1) and the upper washer (2) each include a hole (5) in their body
through which the main
bolt (9) passes. The tensile load in the main bolt (9) acts through the top
work piece (6) and the
nut (8) to compress the lower washer (1) and the upper washer (2) of the load
relief washer
assembly together.
To activate the load relief washer, the upper washer (2) is rotated relative
to the lower
washer (1), sliding along the mating surfaces (3). Once enough relative
rotation between the
lower washer (1) and the upper washer (2) is achieved, the complimentary
stepped features (4)
align, allowing the lower washer (1) and the upper washer (2) to move toward
each other. Said
movement creates a gap (10) between the upper washer (2) and the nut (8),
thereby reducing the
tensile load in the main bolt (9). The reduction of the tensile load in the
bolt (9) corresponds to a
reduction in the forces on the threaded features of the nut (8) and the main
bolt (9); thus, the
bolted assembly may be disassembled with minimal risk of galling.
There is also provided another embodiment of the load relief washer assembly
(FIGS. 20
to 21) comprising a lower washer piece (11), an upper washer piece (12), sets
of four
complimentary stepped features (14) which comprise the mating surfaces of the
lower washer
(11) and the upper washer (12), and a plurality of sliding planes (13) created
by the interface of
the lower washer (11) and the upper washer (12).
There is provided another embodiment of the load relief washer assembly (FIG.
22)
comprising a lower washer piece (15), an upper washer piece (16), 8 sets of
complimentary
6
CA 02794673 2012-11-02
stepped features (18) which comprise the mating surfaces of the lower washer
(15) and the upper
washer (16), and a plurality of sliding planes (17) created by the interface
of the lower washer
(15) and the upper washer (16).
There is provided another embodiment of the load relief washer assembly (FIGS.
23 to
25) comprising a lower washer piece (19), an upper washer piece (20) with a
dodecagonal
feature, a plurality of complimentary stepped features (22) which comprise the
mating surfaces
of the lower washer (19) and the upper washer (20), and a plurality of sliding
planes (21) created
by the interface of the lower washer (11) and the upper washer (12).
There is provided another embodiment of the load relief washer assembly (FIGS.
26 to
28) comprising a lower washer piece (23), an upper washer piece (24) with a
splined feature
(25), a plurality of complimentary stepped features which comprise the mating
surfaces of the
lower washer (23) and the upper washer (24), and a plurality of sliding planes
created by the
interface of the lower washer (23) and the upper washer (24).
There is provided another embodiment of the load relief washer assembly (FIGS.
29 to
30) comprising a lower washer piece (26), an upper washer piece (27) with a
plurality of
transverse holes (28), a plurality of complimentary stepped features which
comprise the mating
surfaces of the lower washer (26) and the upper washer (27), and a plurality
of sliding planes
created by the interface of the lower washer (26) and the upper washer (27).
There is also provided an embodiment with multiple load relief washer
assemblies (FIGS.
31 to 32) combined with threaded bolts (30) and threaded nuts (8) to clamp
common flanges (29)
together. The load relief washer assemblies each comprise of a lower washer
piece (1), an upper
washer piece (2), a plurality of complimentary stepped features which comprise
the mating
surfaces of the lower washer (1) and the upper washer (2), and a plurality of
sliding planes
7
CA 02794673 2012-11-02
created by the interface of the lower washer (1) and the upper washer (2). The
lower washer (1)
and the upper washer (2) each include a hole in their body through which a
main bolt or stud
may pass.
Other aspects and advantages will be more readily apparent as the present
invention
becomes better understood by reference to the following detailed description
and considered in
connection with the accompanying drawings in which like reference symbols
designate like
elements throughout the figures.
The features of the present invention which are believed to be novel are set
forth with
particularity in the appended claims.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
FIG. 1 is a top isometric view showing the load relief washer assembly
according to an
embodiment of the present invention.
FIG. 2 is a bottom isometric view of FIG. 1 showing the stepped features.
FIG. 3 is a side view of FIG. 1 showing the alignment of various parts.
FIG. 4 is a bottom view of FIG. 1 showing the hole through which the main stud
or bolt
may pass.
FIG. 5 is a bottom isometric view of FIG. 1 with the bottom washer removed
showing the
top washer.
FIG. 6 is a side view of FIG. 1 with the bottom washer removed showing the
stepped
features of the top washer.
8
CA 02794673 2012-11-02
FIG. 7 is a bottom view of FIG. 1 with the bottom washer removed showing the
layout of
the top washer.
FIG. 8 is a top isometric view of FIG. 1 with the top washer removed showing
the bottom
washer.
FIG. 9 is a bottom isometric view of FIG. 1 with the top washer removed
showing the flat
surface of the bottom washer.
FIG. 10 is a side view of FIG. 1 with the top washer removed showing the
stepped
features of the bottom washer.
FIG. 11 is a top isometric view showing the load relief washer assembly in the
activated
position according to an embodiment of the present invention.
FIG. 12 is a bottom isometric view of FIG. 11 showing the stepped features.
FIG. 13 is a side view of FIG. 11 showing the alignment of various parts.
FIG. 14 is an isometric view of a load relief washer with a bolted assembly
including a
headed bolt, a nut, and two clamped work pieces.
FIG. 15 is a side view of FIG. 14 showing a load relief washer with a bolted
assembly
including a headed bolt, a nut, and two clamped work pieces.
FIG. 16 is a full section view of FIG. 14 showing a load relief washer with a
bolted
assembly including a headed bolt, a nut, and two clamped work pieces.
FIG. 17 is an isometric view of an activated load relief washer with a bolted
assembly
including a headed bolt, a nut, and two work pieces.
FIG. 18 is a side view of FIG. 17 showing an activated load relief washer with
a headed
bolt, a nut, two clamped work pieces, and a gap between the nut and top
washer.
FIG. 19 is a full section view of FIG. 17 showing an activated load relief
washer with a
9
CA 02794673 2012-11-02
bolted assembly and a gap between the nut and top washer.
FIG. 20 is a top isometric view showing a load relief washer assembly
according to an
embodiment of the present invention with three step levels.
FIG. 21 is a bottom isometric view of FIG. 20 showing a load relief washer
assembly
with three step levels.
FIG. 22 is an isometric view showing a load relief washer assembly according
to an
embodiment of the present invention with 8 sets of stepped features.
FIG. 23 is a top isometric view showing a load relief washer assembly
according to an
embodiment of the present invention with a dodecagonal feature on the top
washer.
FIG. 24 is a bottom isometric view of FIG. 23 showing a load relief washer
assembly
with a dodecagonal feature on the top washer.
FIG. 25 is a top view of FIG. 23 showing a load relief washer assembly with a
dodecagonal feature on the top washer.
FIG. 26 is a top isometric view showing a load relief washer assembly
according to an
embodiment of the present invention with a splined feature on the top washer.
FIG. 27 is a bottom isometric view of FIG. 26 showing a load relief washer
assembly
with a splined feature on the top washer.
FIG. 28 is a top view of FIG. 26 showing a load relief washer assembly with a
splined
feature on the top washer.
FIG. 29 is an isometric view showing a load relief washer assembly according
to an
embodiment of the present invention with transverse holes on the top washer.
FIG. 30 is a side view of FIG. 29 showing a load relief washer assembly with
transverse
holes on the top washer.
CA 02794673 2012-11-02
FIG. 31 is an isometric view of multiple load relief washers with a bolted
assembly
including headed bolts, nuts, and two clamped circular flanges.
FIG. 32 is a side view of FIG. 31 showing multiple load relief washers with a
bolted
assembly including headed bolts, nuts, and two clamped circular flanges.
DETAILED DESCRIPTION OF THE INVENTION
With reference to the annexed figures, the preferred embodiments of the
present
invention will be herein described for indicative purposes and by no means
represent limitations.
The figures and description attached to it are only intended to illustrate the
idea of the
invention. As to the details, the invention may vary within the scope of the
claims. So, the size
and shape of the tension relief system may be chosen to best fit the fastened
assembly.
Also, as used hereinabove and hereinafter, the term "stud" generally refers to
stud, bolt,
rod and other similarly shaped fasteners used in securing assemblies.
In accordance with the present invention, there is provided a load relief
washer assembly
for threaded fasteners (FIGS. 1 to 19) comprising a lower washer piece (1), an
upper washer
piece (2), a plurality of complimentary stepped features (4) which comprise
the mating surfaces
of the lower washer (1) and the upper washer (2), and a plurality of sliding
planes (3) created by
the interface of the lower washer (1) and the upper washer (2). The lower
washer (1) and the
upper washer (2) each include a hole (5) in their body through which a main
bolt or stud may
pass.
A first embodiment of the present invention is best shown in FIGS. 1 to 3 and
FIGS. 13
to 19. Its components comprise a lower washer piece (1), an upper washer piece
(2), a plurality
11
CA 02794673 2012-11-02
of complimentary stepped features (4) which comprise the mating surfaces of
the lower washer
(1) and the upper washer (2), and a plurality of sliding planes (3) created by
the interface of the
lower washer (1) and the upper washer (2). A threaded bolt (9) passes through
holes (5) in the
bodies of the lower washer (1) and the upper washer (2) and mates with a
threaded nut (8) to
clamp two work pieces (6) together. The stud (9) can pass through holes in the
two work pieces
(6) wherein the stud (9) can have an integral hex head (7) (see FIGS. 14 to
19) to allow it to be
turned into place using external means, such as a hex socket. Alternatively,
the stud can pass
through holes in the two work pieces (6) and thread into a standard nut under
the bottom work
piece (6), or the stud (9) can be threaded into the bottom work piece (6).
The tensile load in the main bolt (9) clamps the load relief washer assembly
and the work
pieces (6) together, thereby making the load relief washer part of the bolted
assembly. The nut
(8) bears down on the upper washer (2), and the top work piece (6) similarly
compresses the
lower washer (1). However, relative movement of the upper washer (2) and the
lower washer (1)
towards each other is inhibited by their raised, stepped features (4); thus,
the tensile load in the
main bolt (9) is transferred to the plurality of sliding planes (3) created by
the interface of the
lower washer (1) and the upper washer (2).
To activate the load relief washer, the upper washer (2) is rotated relative
to the lower
washer (1), sliding along the mating surfaces (3). In this example, a
hexagonal shaped feature is
included to aid in achieving said rotation though external means, such as a
hex socket. Once
enough relative rotation between the lower washer (1) and the upper washer (2)
is achieved, the
complimentary stepped features (4) align, allowing the lower washer (1) and
the upper washer
(2) to move toward each other. As the overall thickness of the bolted assembly
is reduced, bolt
stretch of the main stud (9) is alleviated and the tensile load lessens. If
necessary, the height of
12
CA 02794673 2012-11-02
the bolted assembly can be reduced past the point of removing stretch of the
main stud (9),
thereby creating a gap (10) between the upper washer (2) and the nut (8). The
reduction of the
tensile load in the bolt (9) corresponds to a reduction in the forces on the
threaded features of the
nut (8) and the main bolt (9); thus, the bolted assembly may be disassembled
with minimal risk
of galling.
It is to be understood that even though a stud (9) with an integral head (7)
has been
shown, the use of other types of studs and other types of mating techniques
between the studs
and work pieces (6) are also contemplated. For example, the mating of the stud
(9) with the
lower work piece (6) could be effected with a normal threaded nut which is
threaded on a stud
until it abuts on and mates with the lower work piece (6). Therefore, the
present invention is not
limited to a particular mating technique between the stud (9) and work pieces
(6).
In another embodiment, multiple instances of the present invention are shown
installed
on the face of a circular flange (FIGS. 31 to 32). The stud bolts (30) are
inserted through the
lower washers (1), upper washers (2), threaded nuts (8), and the corresponding
flanges (29) that
are mating together.
There is provided another embodiment of the load relief washer assembly (FIGS.
20 to
21) comprising a lower washer piece (11), an upper washer piece (12), sets of
four
complimentary stepped features (14) which comprise the mating surfaces of the
lower washer
(11) and the upper washer (12), and a plurality of sliding planes (13) created
by the interface of
the lower washer (11) and the upper washer (12). The greater number of stepped
features (14)
allows activation to be achieved with less rotation of the lower washer (11)
and the upper washer
(12).
There is provided another embodiment of the load relief washer assembly (FIG.
22)
13
CA 02794673 2012-11-02
comprising a lower washer piece (15), an upper washer piece (16), 8 sets of
complimentary
stepped features (18) which comprise the mating surfaces of the lower washer
(15) and the upper
washer (16), and a plurality of sliding planes (17) created by the interface
of the lower washer
(15) and the upper washer (16). The greater number of sets of complimentary
stepped features
(18) allows activation to be achieved with less rotation of the lower washer
(15) and the upper
washer (16) and can change the load distribution.
Also, it is to be understood that even though select step-like features have
been shown,
the use of other types and shapes of the steps (4) are also contemplated. For
example, said
features could be castellated, slightly angled, or linear rather than annular.
Therefore, the present
invention is not limited to the particular type, shape, or number of the steps
(4).
There is provided another embodiment of the load relief washer assembly (FIGS.
23 to
25) comprising a lower washer piece (19), an upper washer piece (20) with a
dodecagonal
feature, a plurality of complimentary stepped features (22) which comprise the
mating surfaces
of the lower washer (19) and the upper washer (20), and a plurality of sliding
planes (21) created
by the interface of the lower washer (11) and the upper washer (12). The
dodecagonal feature is
included to aid in achieving relative rotation of the lower washer (11) and
the upper washer (12)
though external means, such as a 12-point socket.
There is provided another embodiment of the load relief washer assembly (FIGS.
26 to
28) comprising a lower washer piece (23), an upper washer piece (24) with a
splined feature
(25), a plurality of complimentary stepped features which comprise the mating
surfaces of the
lower washer (23) and the upper washer (24), and a plurality of sliding planes
created by the
interface of the lower washer (23) and the upper washer (24). The splined
feature (25) is
included to aid in achieving relative rotation of the lower washer (23) and
the upper washer (24)
14
CA 02794673 2014-12-29
though external means, such as a splined socket.
There is provided another embodiment of the load relief washer assembly (FIGS.
29 to 30) comprising a lower washer piece (26), an upper washer piece (27)
with a plurality
of transverse holes (28), a plurality of complimentary stepped features which
comprise the
mating surfaces of the lower washer (26) and the upper washer (27), and a
plurality of
sliding planes created by the interface of the lower washer (26) and the upper
washer (27).
The transverse holes (28) are included to aid in achieving relative rotation
of the lower
washer (26) and the upper washer (27) though external means, such as a spanner
wrench
or tommy wrench.
Also, it is to be understood that even though hexagonal and other select
features
have been shown to aid in activation of the device, the use of other types of
aids are also
contemplated. For example, activation could be aided by rectangular, toothed,
gear-like, or
roughed features. Additionally, no supplementary activation aiding feature is
necessary.
Therefore, the present invention is not limited to a particular feature to aid
in achieving
relative rotation of the lower washer (1) and the upper washer (2).
Obviously, even if only some shapes of load relief washer assemblies have been
shown and described, the skilled addressee will understand that the lower
washer (1) and
the upper washer (2) of the present invention could be provided in a variety
of shapes and
sizes according to the specific needs of a specific bolted assembly.
Thus, although preferred embodiments of the invention have been described in
detail herein and illustrated in the accompanying figures, it is to be
understood that the
invention is not limited to these precise embodiments and that various changes
and
modifications may be effected therein without departing from the scope of the
present
invention.
