Improvements in and relating to Underground Conduits for Electric Wires.
Year: 1892

page_text: Date of Application, 9th Jan., 1892
Complete Specification Left, 30th Sept., 1892-Accepted. 10th Dec.. 1892-
PROVISIONAL SPECIFICATION.
Improvements in and relating to Underground Conduits for Electric
Wires.
I CARL AXEL Wilhelm HultmAN Engineer of Johannesgatan 28 Stockholm
in the Kingdom of Sweden do hereby declare the nature of this invention to be
as follows:-
All conduits for underground electric wires by which the cables pass through
pipes or longitudinal passages in blocks of cement or other similar material placed
after each other have always proved not to be so practical as desired for the reason
that the separate blocks by settling or heaving of the surrounding earth mass
have easily yielded relatively to each other whereby it has been impossible to draw
in the cables.
Conducts or conduits made in accordance with this system have moreover proved
very fragile so that cracking at the joint ensues and as a consequence the tightness
is affected and the efficiency of the conduit materially impaired.
My invention is designed to remove these existing defects and the different means
which I have devised to this end are shown in detail in the accompanying drawing
in which
Fig. 1 represents an elevation of my improved cement block.
Figs. 2 and 3 are cross sections respectively of the same in two different sizes
the former being designed for 9 the latter for 15 cables.
Fig. 4 represents in elevation part of a conduit composed of such blocks having
my improvements applied thereto a portion being broken away to show the
interior.
It will be observed of the sectional views Figs. 2 and 3 that the exterior faces of
the cement blocks are provided lengthwise with rectangular or nearly rectangular
grooves a.
In these grooves are inserted iron bars & smaller than the grooves in their
section. The bars are cut off in lengths so as to allow the joints between them
(shown at c) to get their place at a suitable distance from the joints of the cement
blocks and preferably in the middle between two joints of the blocks, and it is also
preferred that the bars be so disposed or placed that on each block there shall be
only one joint of the bars. The vacant space left in the grooves after the insertion
of the bars therein and the space above the latter may be filled in with cement in
order to hold the bars as firmly as if they were originally founded or cast in with
the blocks. In order to get the two sections in proper position the reduced and
bevelled or partially tapered adjacent ends de of any two blocks must be carefully
adjusted straight in line one with another without positively abutting or being in
actual contact one against the other but so as to allow a distance between the
bevels of say one centimeter. These joints between the blocks may be covered
and filled in the following way. Around the reduced ends of the blocks and
covering the space (of 1 centimeter) between the respective bevels may be wrapped
a piece of hempen cloth soaked in melted asphaltum and whereby the material used
in jointing may be prevented from dropping in between the blocks and closing or
shutting up the pipes. The annular groove formed by two adjacent reduced ends
and consequently around the joint of the blocks may be now filled with cement
or asphaltum as indicated at fin Fig. 4.
The asphaltum fillings afford considerable advantage over other packing materials
known to me for the reason that they allow compressing and expanding of the
illing without cracking of the same.
For this reason a certain lengthwise expansion of the blocks can take effect

page_text: without any risk or fear that crackings affecting the tightness of the joints
would arise.
As the lengthwise expansion of the blocks however is inconsiderable it is not
necessary to fill all joints with the asphaltum but it is generally quite enough if
alternate ones or every third one be filled with this material and the rest of the
joints with cement.
This system for underground conduits has consequently the great advantage of
being flexible and by turning or bending the bars in the desired form the conduits
can be placed in any required curves.
Instead of bars, tubes of iron or other metal may be used. The bars or tubes
can of course also be founded or embodied in the very blocks themselves in the
process of fabricating the blocks instead of being afterwards placed in grooves in
the exterior faces of the same.
Dand this oth
1005
COMPLETE SPECIFICATION.
Improvements in and relating to Underground Conduits for Electric
Wires.
I CARL AXEL WILHELM HULTMAN Engineer of Johannesgatan 28 Stockholm
in the Kingdom of Sweden do hereby declare the nature of this invention and in
what manner the same is to be performed to be particularly described and ascer-
tained in and by the following statement :-
All conduits for underground electric wires by which the cables pass through
pipes or longitudinal passages in blocks of cement or other similar material, placed
after each other, have always proved not to be so practical as desired, for the
reason that the separate blocks, by settling or heaving of the surrounding earth mass,
have easily yielded, relatively to each other whereby it has been impossible to draw
in the cables.
Conducts or conduits made in accordance with this system have moreover proved
very fragile, so that cracking at the joint ensues, and as a consequence the tightness
is affected and the efficiency of the conduit is materially impaired.
My invention is designed to remove these existing defects, and the different
means which I have devised to this end are shown in detail in the drawings left
with the Provisional Specification in which
Fig. 1 represents an elevation of my improved cement block.
Figs. 2 and 3 are cross sections respectively of the same in two different sizes,
the former being designed for 9 the latter for 15 cables.
Fig. 4 represents in elevation, part of a conduit composed of such blocks having
my improvements applied thereto, a portion being broken away to show the
interior.
It will be observed of the sectional views Figs. 2 and 3 that the exterior faces of
the cement blocks, are provided lengthwise with rectangular or nearly rectangular
grooves a.
In these grooves are inserted iron bars 6 smaller than the grooves in their
section. The bars are cut off in lengths so as to allow the joints between them
(shown at c) to get their place at a suitable distance from the joints of the
cement blocks, and preferably in the middle between two joints of the blocks,
and it is also preferred that the bars be so disposed or placed, that on each block
there shall be only one joint of the bars. The vacant space left in the grooves
after the insertion of the bars therein, and the space above the latter may be filled
in with cement, in order to hold the bars as firmly as if they were originally
founded or cast in with the blocks. In order to get the two sections in proper
position the reduced and bevelled or partially tapered adjacent ends d, e of any two

page_text: blocks must be carefully adjusted straight in line one with another, without
positively abutting or being in actual contact one against the other, but so as
to allow a distance between the bevels of say one (1) centimeter. These joints
between the blocks may be covered and filled in the following way. Around the
reduced ends of the blocks, and covering the space (of 1 centimeter) between the
respective bevels, may be wrapped a piece of hempen cloth soaked in melted
asphaltum and whereby the material used in jointing may be prevented from
dropping in between the blocks and closing or shutting up the pipes. The annular
groove formed by two adjacent reduced ends and consequently around the joint of
the blocks may now be filled with cement or asphaltum as indicated at f'in Fig. 4.
The asphaltum fillings afford considerable advantage over other packing materials
known to me, for the reason that they allow compressing and expanding of the
filling without cracking of the same.
For this reason a certain lengthwise expansion of the blocks can take effect,
without any risk or fear that crackings affecting the tightness of the joints would
arise.
As the lengthwise expansion of the blocks however is inconsiderable, it is not
necessary to fill all joints with the asphaltum, but it is generally quite enough if
alternate ones or every third one be filled with this material, and the rest of the
joints with cement.
This system for underground conduits has consequently the great advantage of
being flexible, and by turning or bending the bars in the desired form, the conduits
can be placed in any required curves.
Instead of bars, tubes of iron or other metal may be used. The bars or tubes
can of course also be founded or embodied in the very blocks themselves in the
process of fabricating the blocks, instead of being afterwards placed in grooves in
the exterior faces of the same.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I declare that what I
claim is.
1. As a means for strengthening and holding in place cement or other blocks
employed as conduits for underground electric cables or wires, metallic bars or
tubes combined with such blocks and lodged in exterior longitudinal grooves
therein, larger in cross section than such bar or tube, and secured therein by a
suitable cementing material, all substantially as set forth.
2. Blocks for underground electric cables or wires having their ends reduced and
bevelled as set forth, and having the adjacent ends of such blocks wrapped with
hempen or other cloth, prepared with asphaltum as described, and some of the said
joints then filled with a suitable cement and others with asphaltum or suitable
flexible material.
Dated this 29th day of September 1892.
HERBERT & Co.,
•
18, Buckingham Street, Strand, London, W.C., Agents to Applicant.