Cable bed and cable laying method

A roller-support rung arrangement for a cable bed and a cable laying method utilizing the arrangement are disclosed. The cable bed has roller rungs and support rungs on which support blocks are to be mounted. Generally, the roller rungs are mounted on the side rails at a higher level than the support rungs so that a cable drawn onto the cable bed initially contacts only the roller rungs for easy drawing of the cable. Generally, the support blocks are provided on the support rungs after the cable is initially laid on the cable bed such that the support blocks can substantially support the cable weight.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention generally relates to a ladder-type cable bed. This invention 
more particularly relates to a ladder-type cable bed incorporating roller 
rungs, which utilizes cable support blocks to be mounted on support rungs 
after an initial cable laying operation. This invention also relates to a 
cable laying method using such a cable bed. 
2. Prior Art 
Japanese Laid-Open Utility Model Publication 62-172210 discloses a 
ladder-type cable bed 1 incorporating & plurality of roller rungs 10 as 
shown in FIGS. 12 and 13, FIG. 12 being a partial perspective view and 
FIG. 13 being a partial front view with a longitudinally extending side 
wall 2 sectioned. 
Each roller rung 10 comprises a plurality of disk rollers 12 turnably 
mounted on an axial shaft 11 which has a projection 11a (with a threaded 
hole) on each end thereof. Each projection 11a is fixedly connected to a 
corresponding side wall 2 with a threaded bolt 6 screwed through a hole 
provided on the side wall 2 from outside into the threaded hole of the 
projection 11a. A cable W (shown in phantom) generally touches two disk 
rollers 12 of each roller rung 10 (which turn on the axial shaft 11) when 
drawn onto the cable bed 1, and that portion of the cable W is supported 
by the two disk rollers 12 as shown in FIG. 13. 
The cable bed 1 includes a plurality of such roller rungs 10 mounted in 
parallel at intervals across two parallel side walls 1. The cable bed 1 
also includes a plurality of support rungs 3 mounted in parallel at 
intervals across the side walls 2 among the roller rungs 10. In general, 
more support rungs 3 are incorporated in a cable bed 1 than roller rungs 
10 as shown in FIG. 14 partly because roller rungs 10 are much more costly 
to manufacture and much more fragile than support rungs 3. 
In general, a cable or pipe to be drawn onto a (ladder-like) cable bed is 
heavy and long, and generates (during a cable laying or drawing operation) 
considerable friction with the cable bed or its rungs. The roller rungs 10 
are expected to assist in drawing a cable W onto the cable bed 1 while the 
support rungs 3 support a much larger part of the cable weight in an 
attempt to reduce cable traction force. 
Since the support rungs 3 are provided on the cable bed 1 at substantially 
the same level with the roller rungs 10 as shown in FIG. 14 in schematic 
partial side view, the friction generated between the cable W and the 
support rungs 3 during a cable laying operation can be so large that the 
cable drawing operation will be substantially hindered, since 
conventionally the cable W must be and is mostly supported by the support 
rungs 3. 
It is advantageous, therefore, that a cable W does not contact support 
rungs 3 while initially drawn onto the cable bed 1 but contacts only the 
roller rungs 10. 
Such an arrangement may be provided by installing on side walls 2 support 
rungs 3 substantially lower than roller rungs 10. However, in such an 
arrangement, the roller rungs 10, relatively fewer in number, are destined 
to shoulder all weight of the cable W laid on the cable bed 1, which will 
be too much a burden for such fragile conventional roller rungs 10. 
In addition, such an arrangement is impractical conventionally, for it is 
such support rungs 3 that are to support cable weight. Besides holding 
side walls 2 firmly together, conventional support rungs 3 are provided to 
support as well as frictionally hold cables W laid on a cable bed 1 so 
that the cables W once laid on the cable bed 1 will not be displaced 
longitudinally or laterally. 
It is impractical either to provide a cable bed 1 with conventional roller 
rungs 10 alone, for it is required to incorporate too many roller rungs 
10, which will be much more costly than utilizing support rungs 3. 
Accordingly, it is an object of the present invention to provide a 
roller-support rung arrangement, which can efficiently assist in reducing 
traction force from cable drawing and can stably hold a cable or cables 
once laid thereon. 
It is another object of the present invention to provide a cable bed 
incorporating such a roller-support rung arrangement, which can provide an 
easy laying of a cable or cables and stably hold the cable or cables once 
laid thereon. 
It is a further object of the present invention to provide a cable laying 
method using such a cable bed, which can provide an easy laying of a cable 
or cables. 
SUMMARY OF THE INVENTION 
Those objects and other objects of the present invention will be 
accomplished through use of a cable bed incorporating a roller-support 
rung arrangement provided by the present invention in conjunction with a 
cable laying method according to the present invention. 
A roller-support rung arrangement of the present invention is provided by 
using a plurality of roller rungs, a plurality of support rungs and a 
plurality of support blocks. 
A roller rung of the present invention can be any rung having rollers which 
can appropriately turn in cable laying directions, however, it is 
advantageous that such a roller rung is made sturdy enough to support 
substantial weight. 
A roller rung of the present invention includes a plurality of roller disks 
or drums which are arranged in an elongated casing having an elongated 
upper opening provided therethrough such that the roller drums can 
independently rotate within the casing in cable laying directions with 
their upper portions protruding or exposing from the elongated opening to 
directly receive a cable thereon. The elongated casing has connection 
means with which to be mounted in a plurality across a pair of elongated 
side rails which extend longitudinally in parallel. 
Such roller drums can be partitioned with partition panels within the 
casing and turn by means of turnable engagement provided between the 
partition panels and the roller drums. Such roller drums may even be 
provided to turn substantially above the casing turnably supported by 
"tall" partition panels which protrude from the opening and are fixedly 
housed in the casing. 
A support rung to provide a cable bed system of the present invention 
together with a cable bed is prepared with an identical length with a 
roller rung but generally with a shorter height or vertical thickness such 
that when incorporated in a plurality in a cable bed, a cable initially 
contacts only the roller rungs and does not contact or hardly contacts the 
support rungs. 
Each support rung is to be provided thereon with a support block after an 
initial cable laying operation. Each support block is generally given a 
dimension such that when mounted on a support rungs the combined height of 
the support rung and the support block is substantially even with that of 
a roller rung so that the support block can substantially contribute to 
supporting and holding a cable laid thereon in cooperation with the roller 
rungs and other support blocks. 
A cable bed of the present invention incorporates such a roller-support 
rung arrangement generally by mounting such roller rungs and support rungs 
(initially without support blocks) across a pair of generally L-shaped, 
longitudinally extending side rails. As set forth, support blocks are to 
be respectively installed on the support rungs after a cable or cables are 
initially laid on the cable bed contacting substantially only the roller 
rungs so that the roller rungs and support rungs with the support blocks 
thereon can eventually share the weight of the cable or cables laid 
thereon. 
Alternatively, it is possible to provide the combined height of a support 
block and a support rung to substantially exceed the height of a roller 
rung such that a cable or cables laid on a cable bed are eventually 
supported substantially by the support blocks on the support rungs alone. 
A cable laying method according to the present invention generally includes 
the steps: drawing a cable onto such a cable bed without support blocks 
from an end thereof or from a selected middle location of the cable bed 
with an assistance from rotation of the roller drums of the roller rungs; 
and attaching a support block on each support rung under the cable with 
appropriate mounting means after that initial cable laying operation. The 
cable can be less strenuously laid and then stably supported on the cable 
bed.

DESCRIPTION OF PREFERRED EMBODIMENT 
In FIGS. 1 to 3A, a cable bed 1 according to an embodiment of the present 
invention is shown, comprising a pair of L-shaped side rails 2 running in 
parallel, a plurality of support rungs 3 mounted across the side rails 2 
at appropriate intervals, and a plurality of roller rungs 4 mounted across 
the side rails 2 at appropriate intervals among the support rungs 3. An 
arrangement of roller rungs 4 and support rungs 3 along the side rails 2 
is shown in FIG. 3. Other arrangements of roller rungs 4 and support rungs 
3, such as a repetition of a unit consisting of two support rungs and one 
roller rung or one support rung and two roller rungs, are possible. 
In FIG. 1, each support rung 3 has a support block 8 thereon, on which are 
laid three cables W. The support blocks 8 are to be attached on the 
support rungs 3 by means of threaded bolts 9a after a cable or cables W 
are initially laid over the support rungs 3. 
The side rails 2 is advantageously made of aluminum, however, other 
appropriate materials may be utilized as desired. The support rung 3 in 
this embodiment is made of aluminum, however, other materials may be 
utilized as desired. 
In FIG. 2, the support rung 3 formed of a rung body 3a and the support 
block 8 are shown in detail. The support rung 3 has a first groove 3b 
formed through the center portion of the rung body 3a which opens upward. 
A second groove 3c which opens sideway is formed through its inner wall 
within the first groove 3b, as shown in FIG. 2. 
FIG. 2A is a full perspective view of the invention with the supports which 
are detailed in FIG. 2 moved laterally from the drawing in order to 
provide an understanding of the removability of the support rung in order 
to provide for the functionality of the invention. More specifically, as 
is stated herein, support blocks 8 are removed from the balance of the 
invention in order to provide easier pulling of the cable onto the support 
since it would then only contact the roller rungs 4. Subsequent to pulling 
the cable onto the support rack the support blocks 8 would be inserted 
under the cables on support rungs 3 to provide support for the cables W. 
Once the support blocks 8 are inserted in the invention the cable W will 
be supported virtually horizontally and very smoothly without having 
significant sagging points between the roller rungs. Referring to FIG. 3A 
the support blocks 8 are shown inserted in the balance of the invention to 
show their exact location. 
Referring now back to FIG. 2, support block 8 has an arch support face 8a 
(the center portion being the lowest) on a plate member 8b, and a first 
bolt hole 8c is provided adjacent to each end of the support block 8, as 
shown in FIG. 2. The support block 8 is to be fixed on the support rung 3 
with first threaded bolts 9a respectively screwed from above through the 
first bolt holes 8c into the first groove 3b whose width is made slightly 
smaller than the diameter of the first threaded bolts 9a. The elongated 
inner wall portion of the first groove 3b will be provided with thread 
etches as the first threaded bolts 9a is forcibly advanced thereinto, 
firmly fixing the support block 8 on the support rung 3 by means of thread 
engagement between the first threaded bolts 9a and the formed thread 
etches. 
Each side rail 2 has a number of second bolt holes 2a provided therein 
generally in a longitudinal alignment. The support rung 3 is fixed on two 
such side rails 2 running in parallel with two second threaded bolts 9 
respectively and correspondingly screwed through two second bolt holes 2a 
from outside of the side rails 2 into the respective end openings of the 
second groove 3c whose width is made slightly smaller than the diameter of 
the second threaded bolts 9. The second groove 3c will also be provided 
with thread etches as the second threaded bolts 9 is forcibly advanced 
thereinto, firmly fixing the support rung 3 on the side rails 2. In this 
embodiment, each end portion of the support rung 3 is placed on the 
longitudinally extending bottom shelf of the corresponding L-shaped side 
rail 2. 
It is advantageous to provide such a support rung 3 as light and sturdy as 
possible. In this embodiment, the support rung 3 is molded hollow as shown 
in FIG. 2 to satisfy both advantages. It is also advantageous to provide 
such a support block 8 as light as possible. A foam material may be 
advantageously utilized. 
In FIG. 9 is shown a roller rung 4 to be incorporated in a plurality in the 
cable bed 1, comprising an elongated casing 5 formed of an elongated body 
5a having an elongated upper opening provided between two elongated upper 
plate portions 5f, and a plurality of roller drums 6 housed in the casing 
5 exposing their upper portions from the opening to directly receive a 
cable or cables W and rotate in cable laying directions within the casing 
5. The upper plate portions 5f prevent the roller drums 6 from falling off 
the casing 5. 
The roller drums 6 have an axial cylindrical indentation 6a on each side 
and are partitioned with partition panels 7 having axial cylindrical 
protrusions 7a which are slightly smaller in diameter than the 
indentations 6a as shown in FIG. 11. The protrusions 7a correspondingly 
and turnably engage the axial indentations 6a of the roller drums 6 so 
that the roller drums 6 can freely and independently rotate within the 
casing 5 without contacting the caging S. Though not shown, it is possible 
to provide axial indentations on the partition panels 7 and axial 
protrusions on the roller drums 6. 
Alternatively, the roller drums 6 may rotate on an elongated axial shaft 
(not shown) which penetrates the axial centers of the roller drums 6 and 
partition panels 7. Though not shown, the partition panels 7 may be 
provided "tall" or protruding from the opening of the casing 5 such that 
the roller drums 6 turn substantially above the opening. Other types of 
roller rungs such as shown in FIG. 13 (prior art) may be appropriately 
incorporated in the cable bed 1 of the present invention as long as they 
can appropriately facilitate initial drawing of a cable or cables. 
In this example, the casing 5 has a bolt groove 5b on each side of the body 
5a as shown in FIG. 9. The roller rung 4 is fixed on the side rails 2 with 
four second threaded bolts 9 screwed through corresponding four second 
bolt holes 2a into the corresponding bolt grooves 5b from outside of the 
side rails 2. As set forth, each bolt groove 5b has a width slightly 
smaller than the diameter of the second threaded bolt 9. Alternatively, 
the bolt groove 5b may be a cylindrical groove with an elongated opening 
whose width is smaller than the diameter of the second threaded bolt 9. 
It is to be noted that the roller rungs 4 are made considerably taller 
(vertically thicker) than the support rungs 3 such that a cable W drawn 
onto the cable bed 1 initially contacts only the roller rungs 4 and does 
not contact (or hardly contacts) the support rungs 3 as shown in FIG. 3, 
where support blocks 8 are shown in phantom having a height H1. In this 
embodiment, height H2 shown in FIG. 1 between the lowest point (center) of 
the support face 8a and the bottom surface of the support block 8 is 
provided nearly equal to height H1. 
Alternatively, it is possible to mount support rungs 3 on the side rails 2 
substantially lower than roller rungs 4 to attain the foregoing purpose 
with appropriate mounting means. In this case, the height or vertical 
thickness relationship between the roller rungs 4 and support rungs 3 is 
not essential. 
In the following, a cable laying method according to the present invention 
which utilizes a foregoing cable bed 1 is described. 
A cable W is drawn onto a cable bed 1 from an end thereof or at a selected 
midportion thereof, which is received only on the roller rungs 4. The 
rotation of the roller drums 6 which contact the cable W assists the 
drawing and substantially reduces cable traction force. 
Then the support blocks 8 are then attached on the support rungs 3 under 
the cable W. Since there is generally provided space between the laid 
cable W and the support rungs 3, the attachment of the support blocks 8 on 
the support rungs 3 should not be a problem. 
When all the support rungs 3 are provided thereon with a support block 8, 
the cable W is stably held on the cable bed 1. The cable W will hardly be 
displaced longitudinally as the support blocks 8 firmly hold the cable W 
thereon by means of friction generated between the support faces 8a and 
the cable W. The cable W will not be displaced sideway, either, because in 
this embodiment, the support face 8a is configured of an arch with its 
ends higher than its center. 
FIG. 4 shows another embodiment of the support block 8, having a plurality 
of arch support faces, which exclusively and individually hold cables W, 
providing improved prevention of dislocation of cables W. 
In FIGS. 5 and 6, another support block 8 is shown, comprising a cover 
frame 8d having two first bolt holes 8c, and two holder blocks 8e of an 
elastic material which are to be enclosed in the cover frame 8d. Neither 
holder block 8e initially has a cable holding portion, however, since the 
material is elastic and deformable, a cable or cables W can be pressed 
into the holder blocks 8e and firmly sandwiched between the holder blocks 
8e, as shown in FIG. 5. 
It is to be noted that the top surface level of the lower holder block 8e 
when installed in a cable bed 1 is generally even with the top portions of 
the roller drums 6. However, the top surface level of the lower holder 
block 8e may be above the top portions of the roller drums 6. Such support 
blocks 8 are capable of providing still improved prevention of cable 
displacement, which will stable sustain cables W in events of even 
earthquakes. 
A plurality of such "small" support blocks 8 can be mounted on a single 
support rung 3 as shown in FIG. 7. 
Alternatively, an "elongated" support block 8 may be provided, such as 
shown in FIG. 8, basically identically with the foregoing support block 8. 
Alternatively, the holding blocks Be can be made of a "hard" material 
instead of an elastic material, in which case, a plurality of semicircular 
cable holding ditches of an appropriate size are formed in each holding 
block 8e, in corresponding alignment with those formed in the other 
holding block 8e such that the ditches can cooperatively and individually 
hold cables W firmly. 
It is to be noted that it is possible to provide height H2 shown in FIG. 1 
substantially greater than height H1 shown in FIG. 3. That is, with those 
types of support rungs 3 and support blocks 8, the overall height of the 
support rung 3 and support block 8 is greater than that of the roller rung 
4, in which case, a cable W laid on the cable bed 1 will be eventually 
supported on the support blocks 8 alone, the roller rungs 4 contributing 
only at the time of initial cable drawing. 
It is additionally possible to provide a support rung 3 and a support block 
8 as a unit (not shown). In such a case, the support block 8 is originally 
attached on the support rung 3, for example, by appropriate pivotal means 
(not shown) such that the support block 8 can be pivoted in place onto the 
support rung 3 after a cable W is initially laid on the cable bed 1. 
It is also possible to initially arrange a cable bed 1 with only a 
plurality of roller rungs 4. A plurality of support rungs 3 each 
advantageously with a support block 8 mounted thereon may be additionally 
provided on the cable bed 1 after an initial cable laying operation. 
The roller rung 4, support rung 3 or support block 8 may be provided with 
other types of attachment means as long as the respective attachments are 
appropriately provided. 
As described earlier, the support rungs 3 may have a height or thickness 
substantially equal to that of the roller rungs 4 or even greater, in 
which case, the support rungs 3 are mounted on the side rails 2 at a 
substantially lower level than the roller rungs 4. 
It should be noted that the present invention provides laying pipes such as 
water pipes or gas pipes as well. 
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.