Note: Descriptions are shown in the official language in which they were submitted.
1~84~3~
The present invention relates to cable clamps for spacer
dampers.
Spacer dampers for use with bundle conductors comprising
a plurality of sub-conductors or cables are provided with a
plurality of cable clamps for resiliently securing the sub-conduc-
tors or cables to the spacer dampers.
To enable a spacer damper to function successfully in
service, it must be provided with cable clamps which provide an
adequate and continuous clamping pressure on the sub-conductors,
since loss of clamping pressure results in abrasive damage to
the sub-conductors and loss of bundle restoration torque. ~tionally,
the cable clamps must have the ability to compensate for various
natural phenomena such as cold flow (creep) of the aluminium
strands which normally form the sub-conductors, and high cycli-
cal stresses resulting from differential coefficients of expansion.
The clamping stress on the sub-conductors should be
kept to a minimum to avoid damaging the latter, but the gripping
or clamping strength should be sufficient to resist bundle rota-
tional movement caused by unequal ice loading, electrical short
circuit forces, conductor galloping and any other external force
imposed on the conductor, and also to resist longitudinal slip
caused by unequal ice loading of the sub-conductors.
To facilitate field installation and maintenance of the
spacer dampers, it is also desirable to design the cable clamps
so that all of the components thereof are captive, which eliminates
any necessity for removing any of these components when the clamps
are secured to and removed from the sub-conductors.
Conventional cable clamps use a threaded fastener as a
means of applying clamping pressure for securing the cable clamps
to the sub-conductors. However, the use of a threaded fastener
-- 1 -- ;
~ .
1~84~31
for this purpose can result in a wide range of clamping pressure
due to variations in the application of torque to the threaded
fastener. For example, U.S. Patent 3,161,721 to Torr discloses
a device in which the cable is clamped between a pair of pivot-
ally connected jaws. The jaws are heldin theirclamping position by
a lockingdevice comprising a headedshank extending firstly through
a hole or slot in one of the jaws with its head abuttingagainst
that jaw,and secondly through a slot in the other jaw. The shank
has a transverse cotter which i8 adapted to overlie the otherjaw.
During assembly of the clamp it is necessary to ensure
that the orientationof the cotteris suchthat itmay passthrough
the slotin the otherjaw. The shank must then be rotated about its
longitudinal axis to move the cotter into an overlying position.
Since the shankhas limitedlongitudinal movement it is essential
that thehead is heldagainst thejaw duringassembly and whilstthe
shank is rotated. This is both inconvenient and time consuming.
It is an object of the present invention to provide a
novel and improved cable clamp for use in a spacer damper, which
cable clamp at least partially fulfills these requirements.
According to the present invention there is provided a
cable clamp for use with a spacer damper assembly, the clamp com-
prising a clamp body unting means on the clamp body for connect-
ing the cable clamp to a spacer damper assembly; a keeper movable
relative to the clamp body into a clamping position and having
an elongate nose extending toward the mounting means; pivot means
at the opposite end of the body to the mounting means to pivot-
ally connect the keeper and the clamp body; wall means on the
clamp body and the keeper intermedîate the pivot means and the
mounting means defining, in the clamped position, an aperture to
receive a cable; keeper retaining means operable to retain the
~ - 2 -
- 108403~
body and the keeper in the clamped posit~on, the keeper retain-
ing means including a rigid clasp pivotally mounted on the clamp
body intermediate the ends thereof between the wall means and
the mounting means fior pivotal movement of the rigid clasp in a
plane perpendicular to the aperture and swingable in the plane
to release the keeper and permit relative movement of the keeper
and the body; and a resilient liner within the aperture for
gripping engagement around at least a portion of a cable, the
liner being compressed by the body and the keeper in the clamped
position and biasing the keeper and the clasp into mutual engage-
ment; the rigid clasp including a pair of spaced arms intercon-
nected by an intermediate portion spaced from the clamp body, the
intermediate portion engaging the elongate nose on the keeper to
retain the body and the keeper in the clamped position.
Preferably the clasp has a pair of spaced apart arms
interconnected by an intermediate portion spaced from the clamp
body for engaging a portion of the keeper.
Preferably the pivot means comprises an inturned por-
tion at the extremity of each arm of the clasp, each inturned
portion being received in an opening in the clamp body.
The keeper portion, which may be formed as a projection
in the form of a nose, preferably has a transverse groove for
engagement with the intermediate portion of the keeper. The
groove and the openings in the clamp body which are engaged by
the inturned arm ends of the clasp may be positioned so that the
clasp arms detend at an acute angle to a plane containing the
axis of pivotationof the keeperrelative to the clamp body and the
\l
~ ~ 3 ~
-- 1084031
longitudinal axis of the liner, the retainer being inclined in
direction extending from the cable receiving opening and away
from the liner when the intermediate portion is engaged in the
groove.
The invention will be more readily understood from the
following description of a preferred embodiment thereof given,
by way of example, with reference to the accompanying drawing,
in which:
FIGURE 1 shows a view taken in perspective of a cable
clamp embodying the present invention, the cable clamp being shown
in a partly assembled condition;
FIGURE 2 shows a view in transverse elevation of a part
of a liner forming part of the cable clamp of Figure l;
FIGURE 3 shows an end view of the liner part shown in
Figure 2;
- 3a .
--- iO84031
The cable clamp illustrated in the accompanying drawing
has a clamp body 10 and a keeper 11. At one of its ends, the
clamp body 10 is formed with a projection 12, which fits between
projections 14 at the corresponding end of the keeper 11, the
projections 12 and 14 being rounded to allow pivotation of the
keeper 11 relative to the clamp body 10 about a transverse axis.
Borings, of which one is indicated by reference numeral
15, are provided in the projections 14 and are in alignment with
a boring (not shown) through the projection 12, these three bor-
ings having a common axis coinciding with the above-mentioned
axis of pivotation of the keeper 11.
A pivot pin 16 having a splined central portion 17 fits
into the above-mentioned borings with its cylindrical end por-
tions in the borings 15 of the projections 14 on the keeper 11,
and with its central portion engaging the wall of the boring in -
the clamp body projection 12 with sufficient friction to retain
the pivot pin 16 in position relative to the clamp body 10 and
the keeper 11.
The clamp body 10, at the top thereof as viewed in
Figure 1, is formed adjacent the projection 12 with an upwardly
facing recess 18, and the keeper 11, adjacent the projections
14 thereof, is formed with a corresponding recess 19.
Adjacent the reoess 18, the clamp body 10 is formed with
a further recess 20 which extends between opposed, spaced, parallel
and upstanding side walls 21.
The end of the keeper 11 opposite from the projections
14 is formed with a projection in the form of a nose 23 which is
shaped to be received between the walls 21 on pivotation of the
keeper 11 in a clockwise direction, as viewed in Figure 1, to-
wards the clamp body 10.
-- 4 --
iO84031
The above-described cable clamp is further provided
with a resilient liner having two longitudinally separate halves
25 and 26 which, when the clamp is assembled, are received in the
recesses 18 and 19, respectively, and which are identical to one
another. Preferably, the liner halves 25 and 26 are made of a
resilient polyisoprene material or rubber. However, these liner
halves 25 and 26 may be made of any other elastomer which is
suitable for use in cable clamps.
As can be seen from Figures 2 and 3, taken in conjunc-
tion with Figure 1, the liner half 26 has a cylindrical innersurface 28, an outer surface comprising oppositely`divergent
frusto-conical coaxial surfaces 29 and 30, flat semi-annular end
faces 31 and 32 and flat coplanar side surfaces 33 and 34.-
The cylindrical inner surface 28 of the liner half 26is knurled to enable the liner half to securely grip the cable.
The frusto-conical surfaces 29 and 30 merge smoothly mid-
way along the length of the liner half 26 and provide a peri-
pheral concavity extending around the liner half 26 from the
surface 33 to the surface 34. As can be seen in Figure 3, this
concavity is interrupted by a round projection 36, which is
formed in one piece with the remainder of the liner half 26 and
which is also located midway along the length of the liner half
26. The rounded projection 36 is shaped to extend into a corres-
ponding boring 37 provided in the recess 19 of the keeper 11, and
thus serves to releasably secure the liner half 26 to the keeper
11 .
The recess 19 in the keeper 11 is formed with outwardly
divergent frusto-conical surfaces 38 and 39 corresponding in
shape and conical ~ngles to the frusto-conical surfaces 29 and
30 of the liner half 26.
iO8~031
As mentioned above, the liner half 25 is identical to
the liner half 26, and the recess 18 of the clamp body 10 is
formed with outwardly divergent frusto-conical surfaces similarly
corresponding to those of the liner half 25, which also has a
rounded projection (not shown) corresponding to the projection
36 and mating with a boring (not shown) in the clamp body 10 for
releasably securing the liner half 25 to the latter.
For retaining the keeper 11 in a clamping position, in
which the keeper nose 23 extends partially into the recess 20, the
clamp body 10 is provided with a keeper retainer in the form of a
U-shaped clasp indicated generally by reference numeral 40.
The clasp 30 has an intermediate or bridge portion 41 .
extending between opposite parallel arms 42, and the arms 42 have
inturned ends, one of which is indicated by reference numeral 43
in Figure 1, which fit into openings, of which one is indicated
by reference numeral 44, in opposite sides of the clamp body 10,
the inturned ends of the clasp 40 being pivotable in these openings.
The nose 23 of the keeper 11 is formed, at its upper side,
with a transverse groove 46 for engagement with the intermediate
portion 41 of the clasp 40.
Also, the intermediate portion 41 of the clasp 40 is
spaced from the clamp body 10, and more particularly from the
bottom of the recess 20, by a distance which is not merely suff-
icient to receive the nose portion 23 therebetween but which
enables the keeper 11 to be pivoted downwardly into the recess 20
beyond its normal clamping position in order to enable the
intermediate portion 41 of the clasp 40 to be pivoted past the
outer end of the keeper nose to and from the groove 46.
As will be readily apparent to those skilled in the art,
when the above-described cable clamp is in use and a subconductor
iO84031
in the form of a cable is clamped between the two halves 25 and
26 of the liner, the keeper 11 being in its above-described
clamping position with the intermediate portion 41 of the clasp
engaging with the groove 46, the compressed liner halves 25 and
26 resiliently bias the keeper 11 against the clasp 40, thus
ensuring that the intermediate portion 41 of the clasp 40 remains
engaged in the groove 46.
To enable the keeper 11 to be pivoted against the
resilience of the liner and into and beyond its normal clamping
10 position, a manually operable screw clamp of known type may be
employed during the fitting of the cable clamp onto its cable to
enable the clasp 40 to be pivoted over the nose 23 of the keeper
11 .
The end of the clamp body 10 opposite from the projec-
tion 12 may be adapted in any known manner to facilitate assembly
with components of the spacer damper. In the preferred embodiment
it is formed with a transverse boring 48 for receiving a bolt
(not shown), a plurality of recesses 49 being spaced around the
boring 48 at opposite sides of the clamp body 10 for engagement
20 with resilient washers (not shown) as described, for example,
in United Kingdom Patent Specification No. 1,410,622.
As can be seen from Figure 1, the arms 42 of the clasp
40, which are illustrated in the position which they assume when
the keeper 11 is in its clamping position and the intermediate
portion 41 of the clasp is engaged in the groove 46, are not
vertical but are inclined at an acute angle to the vertical.
More particularly, the groove 46 and the openings 44 are
positioned relative to one another so that the clasp arms 42
and the intermediate portion 41 have their axes in a common plane
30 which extends at an acute angle to a plane containing the axis of
108403~
pivotation of the keeper 11, i.e. the axis of the pivot pin 16,
and the longitudinal axis of the liner, i.e. the axis of the
cable which extends through the liner, the clasp 40 being in-
clined in a direction extending from the openings 44 and away
from the liner.
This arrangement ensures that the intermediate portion
41 is retained in the groove 46 and that pivotal movement of
the clasp 40 in a direction to unlock the keeper 11 requires
displacement of the keeper 11 in a direction which further com-
presses the liner and therefore increases the bias.
The development described hereinbefore represents a
clear advance in the art which will benefit the industry and
the public generally.
