U.S. patent application number 09/845866 was filed with the patent office on 2001-08-23 for wedge clamp type termination for elevator tension member.
This patent application is currently assigned to Otis Elevator Company. Invention is credited to Baranda, Pedro S., Ericson, Richard J., Rehmer, Dennis J..
Application Number | 20010014996 09/845866 |
Document ID | / |
Family ID | 22839076 |
Filed Date | 2001-08-23 |
United States Patent
Application |
20010014996 |
Kind Code |
A1 |
Ericson, Richard J. ; et
al. |
August 23, 2001 |
Wedge clamp type termination for elevator tension member
Abstract
A tension member termination device optimized for terminating
flat tension members having compressible outer coatings, the device
including a wedge and a socket each having cooperating surfaces
positioned at a predetermined angle for clamping the tension member
therebetween. The angle reliably secures the tension member while
avoiding deleterious pressure and stress upon the tension member.
The invention also provides a safety clamp for optional use with
the tension member termination device.
Inventors: |
Ericson, Richard J.;
(Southington, CT) ; Rehmer, Dennis J.; (Bristol,
CT) ; Baranda, Pedro S.; (Farmington, CT) |
Correspondence
Address: |
Sean W. O'Brien
Ten Farm Springs
Farmington
CT
06032
US
|
Assignee: |
Otis Elevator Company
Farmington
CT
|
Family ID: |
22839076 |
Appl. No.: |
09/845866 |
Filed: |
April 30, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09845866 |
Apr 30, 2001 |
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09224045 |
Dec 31, 1998 |
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6256841 |
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Current U.S.
Class: |
24/136R |
Current CPC
Class: |
B66B 7/085 20130101;
B66B 7/062 20130101; F16G 11/04 20130101; Y10T 24/3969
20150115 |
Class at
Publication: |
24/136.00R |
International
Class: |
F16G 011/00 |
Claims
What is claimed is:
1. A termination device for a tension member comprising: a socket
having at least one jaw surface; and a wedge having a centerline
and at least one clamping surface positioned at a predetermined
angle from the centerline, the wedge disposed within the socket
with the at least one clamping surface juxtaposed to the jaw
surface.
2. The termination device as set forth in claim 1 wherein the
tension member is disposed between the clamping surface and the jaw
surface.
3. The termination device as set forth in claim 2 wherein the
tension member includes a tensile force providing a normal force
between the clamping surface and the jaw surface clamping the
tension member therebetween.
4. The termination device as set forth in claim 3 wherein the
tensile force is T, the predetermined angle is .phi., and the
normal force is F.sub.n and is provided in accordance with the
formula: F.sub.n=T/tan .phi.
5. The termination device as set forth in claim 4 wherein the
clamping surface includes a length, L, the tension member has a
width, W, and includes a maximum compressive stress capability,
.sigma..sub.c, and wherein the minimum predetermined angle is
determined in accordance with the formula:
.phi.=tan.sup.-1(T/(.sigma..sub.c*L*W))
6. The termination device as set forth in claim 5 wherein the
tension member is comprised of a inner load carrying member
comprised of a first material and an outer portion comprised of a
second material, wherein the outer portion defines a traction
surface for the tension member, and wherein the normal force
produces a stress less than the maximum compressive stress
capability of the outer portion.
7. The termination device as set forth in claim 6 wherein the
compressive stress capability of the outer material limits L and
.phi..
8. The termination device as set forth in claim 7 maximum
compressive stress capability of the outer material is from about
2.5 MPa to about 5 MPa.
9. The termination device as set force claim 5 wherein the
predetermined angle ranges from about 9 degrees to about 10 degrees
and the length is about 140 mm.
10. The termination device as set forth in claim 1 wherein the
tension member comprises a substantially round cross sectional
shape or a substantially rectangular cross sectional shape.
11. The termination device as set forth in claim 3 wherein the
tension member comprises a substantially rectangular cross section
having a lead portion, a wrap portion and a tail portion, the at
least one jaw surface comprises a first jaw surface and a second
jaw surface, the at least one clamping surface comprises a first
clamping surface and a second clamping surface positioned on either
side of a plane passing through the centerline, the wedge further
comprises a wrap section comprising a semi-circular shape disposed
substantially tangentially between the first clamping surface and
the second clamping surface, and wherein the lead portion is
disposed between the first clamping surface and the first jaw
surface, the wrap portion is disposed on the wrap section and the
tail portion is disposed between the second clamping surface and
the second jaw surface.
12. The termination device as set forth in claim 11 wherein the
semicircular shape has a diameter ranging from about 60 mm to about
70 mm.
13. The termination device as set forth in claim 11 wherein the
socket has an aperture and an opening further and wherein the lead
portion and the tail portion extend through the aperture and the
wedge is disposed within the opening.
14. The termination device as set forth in claim 11 wherein the
wedge comprises a pair of ridges positioned orthogonally at each
edge of the first and second clamping surfaces defining a channel
therebetween receiving the tension member and contacting the jaw
surface and limiting the normal force thereof.
15. The termination device as set forth in claim 13 further
comprising a connecting rod attached to the socket in axial
alignment with the aperture.
16. The termination device as set forth in claim 15 further
comprising a pivot block pivotally connected to the socket and
wherein the connecting rod is attached to the pivot block.
17. A termination device as set forth in claim 1 wherein at least
one of the clamping surface and the jaw surface is textured to
increase the coefficient of friction thereof.
18. A termination device as set forth in claim 3 wherein at least
one of the clamping surface and the jaw surface includes locking
features to mechanically lock the tension member therein.
19. A wedge and socket termination device for a tension member, the
wedge having a clamping surface includes a length, L, and an angle
.phi., the tension member having a tensile force, T, a width, W,
and includes a maximum compressive stress capability,
.sigma..sub.c, and wherein the length, and angle are related in
accordance with the formula:
.phi.=tan.sup.-1(T/(.sigma..sub.c*L*W)
20. An elevator system having an elevator car, a counterweight and
a tension member extending between the counterweight and the
elevator car, the tension member being terminated to at least one
of the car and the counterweight by a termination device
comprising: a socket having at least one jaw surface; a wedge
having a centerline and at least one clamping surface positioned at
a predetermined angle from the centerline, the wedge disposed
within the socket with the at least one clamping surface juxtaposed
to the jaw surface and the tension member disposed between the
clamping surface and the jaw surface; and a connecting rod
attaching the termination device to at least one of the car and the
counterweight.
21. An elevator system as set forth in claim 17 wherein the tension
member comprises a substantially rectangular cross section having a
lead portion, a wrap portion and a tail portion, the at least one
jaw surface comprises a first jaw surface and a second jaw surface,
the at least one clamping surface comprises a first clamping
surface and a second clamping surface positioned on either side of
a plane passing through the centerline, the wedge further comprises
a wrap section comprising a semi-circular shape disposed
substantially tangentially between the first clamping surface and
the second clamping surface, and wherein the lead portion is
disposed between the first clamping surface and the first jaw
surface, the wrap portion is disposed on the wrap section and the
tail portion is disposed between the second clamping surface and
the second jaw surface.
22. A tension clamp for clamping a lead portion and a tail portion
of a tension member in a double overlap arrangement, the tension
clamp comprising: a first plate having a groove disposed therein
receiving the lead portion and a second plate having a groove
disposed therein receiving the tail portion; and at least one
fastener hole in each of the first and second plates receiving a
fastener and clamping the lead portion and the tail portion
therebetween.
23. The tension clamp as set forth in claim 19 wherein the plates
are generally planar and wherein at least one of the ends of the
plates include a leading edge comprised of curved portion.
24. An elevator system having an elevator car, a counterweight and
a tension member extending between the counterweight and the
elevator car, the tension member having a lead portion and a tail
portion being terminated to at least one of the car and the
counterweight by a wedge and socket termination device and
including a tension clamp comprising: a first plate having a groove
disposed therein receiving the lead portion; a second plate having
a groove disposed therein receiving the tail portion; and at least
one fastener hole in each of the first and second plates receiving
a fastener and clamping the lead portion and the tail portion
therebetween in a double overlap arrangement.
25. A method for terminating a tension member comprising: feeding
the tension member into an aperture of a socket; wrapping the
tension member around a wedge; feeding the tension member back
through the aperture; applying a tensile force in the tension
member; and compressing the tension member between the wedge and
the socket.
26. A method according to claim 25 wherein the compressing
comprises compressing the tension member to a stress level below
the maximum compressive stress capability of the tension member
27. A method according to claim 25 further comprising: positioning
the tension member in a back-to-back arrangement; placing a pair of
plates on either side of the tension member; inserting a plurality
of fasteners through the plates; tightening the fasteners; and
clamping the tension member between the plates in a double overlap
arrangement.
Description
TECHNICAL FIELD
[0001] The present invention relates to elevator systems, and more
particularly to tension members for such elevator systems.
BACKGROUND OF THE INVENTION
[0002] A conventional traction elevator system includes a car, a
counterweight, two or more ropes interconnecting the car and
counterweight, a traction sheave to move the ropes, and a machine
to rotate the traction sheave. The ropes are formed from laid or
twisted steel wire and the sheave is formed from cast iron.
[0003] Although conventional steel ropes and cast iron sheaves have
proven very reliable and cost effective, there are limitations on
their use. One such limitation is the traction forces between the
ropes and the sheave. Typical techniques to increase the traction
forces between the ropes and sheave result in reducing the
durability of the ropes, increasing wear or the increasing rope
pressure.
[0004] Another limitation on the use of steel ropes is the
flexibility and fatigue characteristics of steel wire ropes. The
minimum diameter of a steel rope is dictated mostly by fatigue
requirements and results in a relatively thick rope. The relatively
thick cross section of a steel rope reduces its inherent
flexibility necessitating a sheave having a relatively large
diameter. The larger the sheave diameter, the greater torque
required from the machine to drive the elevator system thereby
increasing the size and cost of the elevator system.
[0005] Another drawback of conventional round ropes is that smaller
sheave diameters increase rope pressure shortening the life of the
rope. Rope pressure is generated as the rope travels over the
sheave and is directly proportional to the tension in the rope and
inversely proportional to the sheave diameter D and the rope
diameter. In addition, the shape of the sheave grooves, including
such traction enhancing techniques as undercutting the sheave
grooves, further increases the maximum rope pressure to which the
rope is subjected.
[0006] In a typical rope driven elevator installation rope wedge
clamps are used for termination purposes. Wedge clamps operate by
securing the elevator rope between opposed angled walls of the
wedge clamps and a tear drop shaped wedge around which the cable is
wound. The wedge acts to cam the rope against the walls of the
wedge clamp during tensioning of the ropes. A benefit of this
design is that the wedge may have a relatively sharp angle
producing a large clamping force. Because the steel ropes have a
high compressive strength the large clamping force has no
deleterious effects on the rope such as crush or creep.
[0007] In attempts to overcome the deficiencies and drawbacks of
conventional round steel ropes for use in elevator systems coated
tension members, including a relatively flat tension member, has
been developed. The flat tension member includes a plurality of
individual load carrying cords encased within a common layer of
coating. An exemplary tension member of the type contemplated in
this application is discussed in further detail in U.S. Ser. No.
09/031,108 filed Feb. 26, 1998 Entitled Tension Member For An
Elevator and Continuation-In-Part Application Entitled Tension
Member For An Elevator filed Dec. 22, 1998 under Attorney Docket
No. 98-2143, both of which are entirely incorporated herein by
reference.
[0008] The coating layer surrounds and/or separates the individual
cords and defines an engagement surface for engaging a traction
sheave. As a result of the configuration of the tension member, the
rope pressure may be distributed more uniformly throughout the
tension member, traction is increased and smaller sheave diameters
are possible.
[0009] A method of terminating and securing flat tension members
involves looping the members over a bar and clamping the end with a
pair of plates. The plates are secured by a plurality of fasteners
that pass through holes provided in the plates. Another method of
terminating flat tension members includes a wedged end fastener
wherein a wedge of material is positioned at the end of the tension
member and clamped by a pair of plates. In such a configuration one
of the plates comprises a wedge shaped cross section cooperating
with the wedge of material and the second plate comprises a cross
section of uniform thickness. The plates are similarly secured by a
plurality of fasteners that pass through holes provided in the
plates. A drawback to these types of termination methods is that
the tension carrying capability of the termination relies solely on
the clamping forces provided by the fasteners. In addition, the
wedge type fastener limits the termination point of the member and
hampers adjustability.
[0010] The above art notwithstanding, scientists and engineers
under the direction of Applicants' Assignee are working to develop
more efficient and durable methods and apparatus to drive elevator
systems.
DISCLOSURE OF THE INVENTION
[0011] According to the present invention, a termination device for
a tension member having a compressible outer coating has a wedge
disposed in a socket having cooperating jaw surfaces. The rope is
wrapped around the wedge and inserted with the socket and clamped
therein by forces generated by the tension in the member and the
cooperation of the wedge and jaw surfaces.
[0012] A principal feature of the present invention is the geometry
of the wedge, particularly the angle of the wedge, including its
length and width. The wedge is sized and the angle is selected to
provide sufficient clamping force to resist slippage of the rope
without exceeding the compressive stress capability of the tension
member. In addition, the wedge comprises a domed top portion to
efficiently distribute the tension of the rope across the
wedge.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is perspective view of an elevator system having a
tension member termination device according to the present
invention;
[0014] FIG. 2 is a perspective view of an embodiment of a
termination clamp, showing an optional tension clamp device;
[0015] FIG. 3 is a cross sectional view of the embodiment shown in
FIG. 2 taken substantially along lines 3-3;
[0016] FIG. 4 is perspective view of an alternate embodiment
showing a pivot block;
[0017] FIG. 5 is a cross sectional view of the embodiment shown in
FIG. 4 taken substantially along lines 5-5;
[0018] FIG. 6 is diagrammatic cross sectional view of a wedge,
tension member and jaw surface showing the relevant geometries and
forces;
[0019] FIG. 7 is a perspective view of an embodiment of a wedge
showing ridges and locking features;
[0020] FIG. 8 is a perspective view of a plate of the tension clamp
of FIG. 2; and
[0021] FIG. 9 is a front plan view of a plate of the tension clamp
of FIG. 8.
BEST MODE FOR CARRYING OUT THE INVENTION
[0022] Illustrated in FIG. 1 is a traction elevator system 12. The
elevator system 12 includes a car 14, a counterweight 16, a
traction drive 18, and a machine 20. The traction drive 18 includes
a tension member 22, interconnecting the car 14 and counterweight
16, and a traction sheave 24. The tension member 22 is engaged with
the sheave 24 such that rotation of the sheave 24 moves the tension
member 22, and thereby the car 14 and counterweight 16. Tension
member 22 is coupled to counterweight 16 and car 14 by terminal
clamp 30. Although shown as a geared machine 20, it should be noted
that this configuration is for illustrative purposes only, and the
present invention may be used with geared or gearless machines. In
addition, although shown as a relatively flat tension member 22, it
should be noted that this too is by way of example and the present
invention may be used with other types of tension members including
round coated tension members.
[0023] An embodiment of terminal clamp 30 is illustrated in more
detail in FIG. 2. Tension member 22 is wrapped around wedge 32 and
disposed within socket 34. Terminal clamp 30 is attached to car 14
and counterweight 16 via attachment rod 36 attached to socket 34 by
pin 38. Attachment rod 36 is coupled to counterweight 16 and car 14
by threaded nuts 40 secured in place by cotter pin 42. Also shown
in FIG. 2 is an optional gripping jaw clamp 50 wherein tension
member 22 is clamped within grooves 52, 54 of plates 56, 58 in a
double overlap arrangement.
[0024] Referring to FIG. 3 clamp 30 operates to provide a secure
termination of tension member 22. In use, lead portion 44 of
tension member 22 is inserted within aperture 46 in the bottom
portion of socket 34, as viewed in the figure, wrap portion 47 of
the tension member is then wrapped around wedge 32 and then tail
portion 48 passed back out through aperture 44. Wedge 32 is then
inserted within opening 60 of socket 34 to the clamp position shown
in FIG. 2 wherein lead portion 44 and tail portion 48 are clamped
between jaw surfaces 62, 64 respectively, of socket 34. Termination
clamp 30 is designed such that tension member 22 and attachment rod
36 are substantially axially aligned to allow for efficient load
transfer and prevents undesirable rotation of termination
clamp.
[0025] Still referring to FIG. 3, in normal operation of the
elevator system 12 (FIG. 1), the tension (T) in lead portion 44 of
tension member 22 is in the direction indicated by arrow 66 which
reacts in wrap portion 47 to force wedge 32 farther into socket 34
in the direction of aperture 46. With the load in tension member 22
forcing wedge 32 into socket 34, a clamping force represented by
arrow 68 clamps lead portion 44 against jaw surface 62 and a
clamping force represented by arrow 70 clamps tail portion 48
against jaw surface 64. Clamping forces 68, 70 are normal to jaws
62, 64 respectively, and to the respective portions of wedge 32 and
are expressed as normal forces (F.sub.n). The clamping forces
generated by jaws 62, 64, together with the friction forces acting
on wrap portion 47, react out the total tension (T) in tension
member 22 thereby retaining the member in clamp 30.
[0026] An alternative embodiment of termination clamp 30 is shown
in FIGS. 4 and 5 wherein attachment rod 36 is attached to pivot
block 72 by pin 38 an in turn pivotally attached to socket 34 by
pivot pin 74 and secured by cotter pin 76. In this particular
embodiment, lead portion 44 of tension member 22 is inserted within
aperture 46 in the bottom portion of socket 34, as viewed in the
figure, wrap portion 47 of the tension member is then wrapped
around wedge 32 and then tail portion 48 passed back out through
aperture 44. Wedge 32 is then inserted within opening 60 of socket
34 to the clamp position shown in FIG. 5 wherein lead portion 44
and tail portion 48 are clamped between jaw surfaces 62, 64
respectively, of socket 34. It is an important feature of this
embodiment that once wedge 32 and tension member 22 are installed
within socket 34 pivot block 72 is then installed to prevent the
wedge from being inadvertently dislodged from the socket if tension
is lost in the member, as will be more fully described hereinbelow.
In addition, this particular embodiment maintains tension member 22
and attachment rod 36 substantially axially aligned to allow for
efficient load transfer. Pivot block 72 also permits angular
displacement of tension member 22 relative to the car 14 or
counterweight 16 without imparting large stresses within attachment
rod 36 or socket 34. Another advantage of this particular
embodiment over that shown in FIGS. 2 and 3 is that the overall
height the socket is reduced because the wedge 32 is inserted
through the top of socket 34. Pivot block 72 is then inserted
within close proximity of the wedge thus reducing the overall
height of termination clamp 30.
[0027] The geometry of wedge 32 is an important factor in producing
normal forces 68, 70 and properly retaining tension member 22. The
relevant parameters of wedge 32 controlling the normal force
F.sub.n are shown with reference to FIG. 6 and include the length
(L) designated by 78, depth (d) represented by 80, angle .phi.
represented by 82 and measured from centerline 83 to clamping
surface 33, 35 and the width (W) of tension member 22 (FIG. 2). The
other factor relevant to controlling the normal forces 68, 70 is
the tension (T) in tension member 22 represented by 66. The
parameters L and d are somewhat dependant on .phi. and are
typically limited by available space in the hoistway (not shown).
Given a nominal tension T, normal forces F.sub.n 68, 70 (FIGS. 3
and 5) are inversely related to .phi.. That is to say, if .phi. is
too small, F.sub.n will be too great and tension member 22 will
experience compressive creep. This is particularly important in an
embodiment where tension member 22 is comprised of a urethane outer
coating, or where the coating is another flexible elastomer, as
they have a maximum compressive stress (.sigma.c) capability of
about 5 MPa before non-recoverable deformation, or creep, occurs.
On the other hand if .phi. is too large the normal forces will be
too small the tension member will slip within termination clamp 30.
It is particularly advantageous to reduce the compressive stress on
tension member 22. One way to reduce the compressive stress is to
increase the length L over which the clamping forces are applied,
however hoistway consideration are generally limiting in this
regard. Taking the above referenced physical parameters in to
consideration, in order to preclude exceeding .sigma..sub.c the
minimum .phi. can be predetermined in accordance with the
formula:
.phi.=tan.sup.-1[T/(.sigma..sub.c*L*W)]
[0028] In a typical application of the present invention for a
tension member having a T of about 2500 N, d ranges from about 60
mm to about 70 mm, L is about 140 mm, .phi. ranges from about 9
degrees to about 10 degrees.
[0029] The present invention will now be described with respect to
a specific example of the termination clamp 30 shown in FIGS. 4 and
5 by referring to FIG. 6. A typical tension member 22, as described
in the above related applications, is comprised of a 30 mm wide
flat flexible rope having a urethane outer coating and has a
maximum tension capability of 30,000 N. As is known in the art, a
safety factor of about 12 is applied to elevator ropes and provides
a maximum tension in member 22 of about 2500 N. Wedge 32 has length
L of 140 mm and angle .phi. of 10 degrees geometrically yielding
diameter d as follows:
d=2(L tan .phi.)=2(140 tan 20/2))=49.37 mm
[0030] The determination of F.sub.n with T equal to 2500 N is as
follows:
F.sub.n=T/sin .phi.=2500/sin (20/2)=14,397 N
[0031] Since F.sub.n is distributed over the entire area of lead
portion 44 the compressive stress .sigma. on the tension member 22
is a function of the area of lead portion, A, clamped between wedge
32 jaw surface 32, and is calculated as follows:
A=L*W=140*30=4,200 mm.sup.2
[0032] The compressive stress in tension member 22 is then
determined as follows:
.sigma.F.sub.n/A=14,397/4,200=3.43 MPa
[0033] In this particular example, the compressive stress limit of
the material is not exceeded and therefore no creep will occur.
[0034] The ability of termination clamp 30 to react out T in lead
section 44 is important and is a function of F.sub.n and the
coefficient of friction (.mu.) between the tension member 22 and
jaw surface 62 and the surface of wedge 32. In the example given,
tension member 22 is comprised of a urethane coating and jaw
surface 62, as well as wedge 32, is smooth steel and a conservative
number for the coefficient friction between the surfaces is about
.mu.=0.25. To properly maintain wedge 32 within socket 34 T must be
preferably substantially reacted out within lead section 44
although a remainder may be transferred into wrap section 47. The
following relation, from clamping theory, provides the maximum
reaction force F.sub.r, or the amount of tension that can be
reacted, in the example given for .mu.=0.25:
F.sub.r=.mu.*F.sub.n=0.25*14,397=3,599 N
[0035] Therefore, recalling that the maximum T in the example given
is 2500 N, all of the tension T will be reacted out of tension
member 22 in the lead portion 44 and the member will not slip
within termination clamp 30.
[0036] An alternative embodiment of the present invention aimed at
increasing the coefficient of friction between the tension member
22 and the jaw surface 62, 64 and wedge 32 comprises a roughened
surface on the jaws and the wedge. In one particular embodiment the
surface is roughened by a sandblasting procedure. Sandblasting of
the surfaces raises the coefficient of friction to 0.35 or greater.
Other methods of increasing the surface friction include etching,
machining, knurling and other suitable equivalents. In addition to
raising the coefficient of friction the roughened surfaces would
form small ridges and valleys. A characteristic of the urethane
coating is its tendency to exhibit cold flow under high loading
conditions. Under the loading conditions described above the
urethane coating cold flows into and around the ridges and valleys,
also referred to as locking features, in the wedge and socket and
provides for a small but effective mechanical lock. The locking
features increase the ability of the termination clamp to resist
slippage of tension member 22. It is within the scope of the
present invention that the locking features may comprise grooves,
striations 83 (FIG. 7), cuts, diamond pattern, or other suitable
equivalents. It is important to note that the locking features
reduce the required normal force as described hereinabove. The use
of locking features as describes allows a reduction in the length
L, or an increase in angle .phi. to further minimize the risk of
creep.
[0037] An alternative embodiment for wedge 32 is shown in FIG. 7
and includes ridges 84, 86 forming a channel 88 therebetween.
Ridges 84, 86 are approximately the height of a cord within the
coating of tension member 22. For example, a particular embodiment
of tension member 22 is 3 mm thick having a cord with a 1.4 mm cord
disposed therein. Ridges 84, 86 for this particular embodiment
would define a channel 88 having a depth of approximately 1 mm.
Tension member 22 is disposed within channel 88 and wedge 32 is
installed within socket 34 as described herein above. The benefit
of ridges 84, 86 are that they contain tension member 22 within
channel 88 given the anticipated cold flow characteristics of the
coating material. In addition, ridges 84, 86 are sized to prevent
compressive stress failure of tension member 22 by limiting the
displacement of wedge 32 within socket 34. In the event that a
higher than anticipated normal force F.sub.n is transferred to the
member ridges 84, 86 will contact jaw surfaces 62, 64 and arrest
the travel of wedge 32 within socket 64.
[0038] Referring now to FIGS. 2, 8 and 9, the above mentioned
optional tension clamp 50 for use with the termination clamp 30 is
illustrated. The purpose of tension clamp 50 is to aid in
terminating and reacting tension in member 22 and to equalize the
tension between lead portion 44 and tail portion 48 as they enter
socket 34. Tension clamp 50 also assists termination clamp 30 in
the unlikely event of that tension member 22 loses tension, such as
for instance, during an abrupt stop of elevator car 14. Tension
clamp 50 is clamped onto the tail portion 48 and lead portion 44
prior to entering socket 34. When engaged with the tension member
22, tension clamp 50 cannot move thereon. Plates 56, 58 as shown
and described are identical, however it is within the scope of the
present invention that the plates are different wherein one plate
has a tension member groove and one plate has no groove.
[0039] As described hereinabove tension clamp 50 comprises a pair
of plates 56, 58 each having a tension member groove 52, 54
approximately the thickness of the tension member 22. Bore holes 51
are provided for through passage of fasteners 53. Plates 56, 58
further include leading edges 55 comprising a generous radius to
facilitate a smooth transition of lead portion 44 and tail portion
48 from socket 34 into tension clamp 50.
[0040] In use, the lead portion 44 is inserted into groove 52 of
plate 56 and tail portion 48 into groove 54 of plate 58 and the
plates are assembled together with fasteners 53. When the bolts 53
are tightened tension member 22 is clamped within the grooves 52,
54 and are held resistant to slippage by plates 56, 58. In this way
the tension member is prevented from moving relative to tension
clamp 50.
[0041] When optional tension clamp 50 is used in conjunction with
termination clamp 30, leading portion 44 and tail portion 48 load
share the full tension created by car 14. In this regard, the
analysis for determining the clamping performance established
herein above is modified to reflect a load sharing in the tension
in each of the cables.
[0042] While preferred embodiments have been shown and described,
various modifications and substitutions may be made thereto without
departing from the spirit and scope of the invention. Accordingly,
it is to be understood that the present invention has been
described by way of illustration and not limitation.
* * * * *