Improvements in Safety Fuses for Electric Devices.
Year: 1897

page_text: This Print is in accordance with the Original Specification as it stands after
Amendment (under Section 11 of the Patents, &c. Act, 1883) as required by
the decision of the Comptroller General of the 6th day of December 1898.
Date of Application, 28th Sept., 1897
Complete Specification Left, 7th Apr., 1898-Accepted, 18th June,
1898
Improvements in Safety Fuses for Electric Devices.
A communication by GEORGE HARRIS GOODHUE, of Brookline, in the County of
Norfolk and State of Massachusetts, Merchant, and FERDINAND AUSTIN HART, of
Hartford, in the County of Hartford and State of Connecticut, Insurance Agent,
both of the United States of America.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of the Agency for Foreign
Patent Solicitors, 6, Lord Street, Liverpool, and 6, Bank Street, Manchester, both in
the County of Lancaster, 118, New Street, Birmingham, in the County of Warwick,
and 322, High Holborn, in the County of Middlesex, Civil Engineer, do hereby
declare the nature of this invention to be as follows:-
.
This invention relates to enclosed fuses and has for its object,
First. The production of a safety-fuse which when connected in a circuit can be
handled or touched, without the possibility of the person touching the device coming
into contact with any part of the circuit.
Second. The production of a safety-fuse which can be used in places where there
are inflammable or explosive gases or substances without the possibility of causing
the ignition or explosion of these gases or substances.
Third. The determination at a definite part of the fuse wire of the rupture of the
same by the fusing effect of the heat produced by the increased current through the
fuse wire.
Fourth. The prevention of noise when the fuse wire is ruptured by the effect of
the increased current.
Fifth., The prevention of the formation of an arc at the point where the fuse wire
breaks.
Sixth. The absorption and distribution of the gases or other substances produced by
the fusing of the fuse wire whereby the force of any explosive action attending this
fusing is rendered harmless.
Seventh. The capability of removing from the enclosing tube or case the substance
produced by the fusing of the fuse wire.
Eighth. The regulation of the carrying capacity of the fuse wire whereby its
rupture by the fusing effect of the increasing current may be predetermined for any
strength of current and for any period of time.
Ninth. The production of means for obtaining with an enclosed fuse wire an
indication on the outside of the case that a rupture of the fuse wire has
occurred.

page_text: These results are attained by the devices hereinafter described in this Specification
and which devices embody the principle of this invention.
The fuse wire passes through a tube or case, which fuse wire may be of the usual
form or material or of any suitable form or material. This case may be cylindrical or
rectangular, or of any convenient form. It may be made of any suitable material,
but if made of a conducting material its ends should be of an insulating material or
insulation should be afforded for the terminals to which the fuse wire is attached. A
convenient material for the tube or case is fibre. A convenient size for general
purposes is about three inches in length by three quarters of an inch in diameter,
but it may be of larger or of smaller dimensions as may be found desirable.
The ends of the tube or case are closed and a convenient means of accomplishing
this result is by means of end pieces, each of which may be held in position by an
insulating ferrule, or in any other suitable manner. In each of the ends of the tube
or case is inserted a piece of metal, round or square in section, and in the form of a
rod or strip, or of any other convenient form. This piece may have in it a
longitudinal perforation for the reception of the fuse wire or the fuse wire may be
otherwise attached to the pieces.
This piece forms a suitable terminal for the fuse wire by means of which connection
of the fuse wire is made with the conducting wire of the circuit, as for example, by
the insertion of these terminals in suitable sockets in standards supported upon a
suitable base-plate, to which standards the conducting wires are connected in any
suitable manner. These standards are best made of sufficient height to prevent the
possibility of contact of the conducting wire with the tube or case.
A boss of insulating material may be placed upon the end of the tube or case,
in order to prevent contact of the tube or case with the support for the conducting
wire..
The inner ends of the terminals project into the adjacent filling and act to conduct
heat away from the fuse wire at that part of the same so as to prevent the possibility
of the fuse wire. fusing near the end of the case.
These inner ends of the terminals are preferably tapered and split and the
perforation for the insertion of the terminal in the end of the tube or case, if preferably
tapered, so that after the terminal is inserted, its inner end will be compressed to
firmly bind the fuse wire and ensure good contact with the same.
Each end of the case is filled with some material different from the fuse wire and
acting to conduct away from that part of the fuse wire which passes through this
filling the heat produced by the passage of the current through the fuse wire.
Several substances can be used for the filling, as for example, asbestos, plaster-of-
Paris, oil, paraffin and my correspondents do not confine themselves to any particular
substance, provided it is different from the fuse-wire and acts to conduct heat away
from the same, but asbestos is preferred and a convenient manner for using this
material is by winding a strip of sheet asbestos around a part of the fuse wire until
such a thickness of covering is secured that when the asbestos covered wire is inserted
into the tube or case, the asbestos will be packed or firmly held in the end of the
tube or case.
Asbestos is insulating, is non-inflammable, is sufficiently heat conducting to conduct
some of the heat away from that part of the fuse wire which is in contact with the
asbestos and by its porous nature it acts to absorb and hold the gases and other sub-
stances produced by the fusing and combustion of the fuse wire by the heat produced
by an increased current passing through the fuse wire, and by its elasticity it yields
to the pressure of the gases and thus in connection with the absorption of the gases
and other substances produced by the fusing and combustion of the fuse wire tends
to prevent harmful results from any explosive action when this fusing and combustion
takes place. It is also coherent and can be packed around the fuse so as to enable
a definite air space to be formed in the enclosing tube or case without the use of a
partition or of a drum.
Between each of the filled ends of the tube or case is a space through which the
fuse wire passes and in order to ensure the rupture of a fuse wire of the same

page_text: conductivity by any predetermined strength of current, and after the passage of a
current for any predetermined time, this space must be of definite dimensions; as
any variation in the dimensions of this space will effect the carrying capacity of the
fuse wire to the point of rupture by an increased current, and it is important in
safety-fuses for electrical circuits that the carrying capacity of the safety-fuse should
be accurately known.
If the filling material is capable of being compacted into each end of the tube or,
case, the definition with accuracy of the space between the fillings can be effected
without a partition but as some of the materials which may be used for filling.must
be otherwise retained in the end of the tube or case there may be placed between
the filling and the space, a transverse inflexible partition perforated for the passage
of the fuse wire but it is preferred to use partitions with any materials as these
partitions act to confine the force of the explosion to the air space and to direct
through the perforation in each partition the heated air, gases or other substances
generated when the fuse wire melts and thus to cause the blowing out of any are
which may be formed..
The proper insulation of the fuse wire in this partition is obtained either by.
making this partition of an insulating. material, or in any other suitable
manner.
The partitions may be separable from the case, and they fit air-tight within the
same and they may be held in position in any suitable manner and be adjustable,
thus permitting a variation in the length of the air space for the purpose of changing
the carrying capacity of the fuse wire.
As the fuse wire in the space between each of the filled ends of the tube or case is
out of contact with any heat-conducting material,, rupture of the fuse wire by the
heat produced by the increased current passing through the fuse wire will take place
at the part of the fuse wire in the above named space, instead of at any other part of
the fuse wire, and the gases or other materials produced by this fusing of the fuse
wire will be mainly, formed in this space.
For the further purpose of preventing the passage of an arc from this space
through the perforation in the partition when the fuse wire is ruptured in this space,
a device may be made use of which is normally held in position by the fuse wire
when this fuse wire is unbroken against a force acting to move this device, which
device automatically covers the perforation in the partition when the fuse wire is
ruptured, and in this part of the tube or case is placed the means whereby an
indication may be given that the rupture of the fuse wire has occurred.
The means for giving this indication may form a part of the covering device and
may be operated thereby or it may be an independent device and either or both of
these devices may be dispensed with.
For giving this indication and for covering, various devices may be adopted.
The device for covering the perforations in the partition through which the fuse
wire passes may. consist of a block of an insulating material perforated for the passage
of the fuse wire and held in position by the fuse wire when the latter is intact, and
moving transversely to the tube or case in substantial contact with or adjacent to the
inside surface of the partition in a tube formed by the partition, a collar on the inside
of the tube or case, and a rim, each around opposite openings in the tube or case,
on opposite sides of the same. The ends of the transverse tube are each preferably.
covered with a cap, and one or both ends of those caps may be removable in order
that the block can be removed from the tube or case and thus permit the removal
from the space of substances produced by the fusing of the fuse wire. On one end
of the block is a rod, or projection, which passes through a cap, and when the fuse is
unbroken, is substantially normal to the outer surface of this cap. On the other end
of the block, a suitable spring is arranged which acts when the block is permitted to
move by the breaking of the fuse wire to move this block so that it covers the
perforation in the partition and also causes the projection from the surface of the cap
of the rod, or other device attached to the block, thus affording a visual indication

page_text: $
that a rupture of 'the fuse wire has occurred. Instead of the rod, any other suitable
device may be used.
A helical spring in a socket in the block has been adopted, but it is obvious that
other forms or arrangements of springs may be used or any other means for moving
the block on the release of the same.
A longitudinal recess surrounding the fuse wire is preferably formed in the block
open towards the space between each of the filled ends of the tube or case and
tapering towards an adjacent partition. The effect of this recess is to bring upon
that part of the fuse wire which is near the perforation in the partition the pressure
of the spring, which moves the block and thus causes a tendency of the fuse wire
to first rupture at that point when the fuse wire is softened by the heat of the increased
current.
This recess also acts to receive the gases produced when the fuse wire is fused
so that the block will have a tendency to be moved by the expansive force of these
gases.
The movement of the covering device produced when the block is released by the
rupture of the fuse wire may be made to open or close an electric circuit for the
purpose of operating electric magnetic devices for giving a visual or an audible
indication, or both, that a rupture of the fuse wire has occurred, or it may be made to
operate or release other mechanism for the same purpose.
One two or more covering devices may be used.
Instead of a perforation a transverse slot may. be used for the passage of the fuse
wire through the covering block.
In one covering device the block rotates in the transverse tube, this rotation
being effected by a suitable spring or by any other suitable means when the fuse wire
breaks.
The visual indication may be given by the movement of an index on the outside of
the tube or case and attached to the block.
The recess àcts to locate the point of rupture of the fuse wire near the perforation in
the partition.
In another device the transverse tube is dispensed with and on each end of the
covering block is a rod which passes transversely through the tube or case.
In another covering device the fuse wire rests upon the end of the block, and this
block is bevelled off towards the partitions.
The withdrawal of the rod attached to the block and normally projecting through
'the side of the tube or case, affords a visual indication that rupture of the fuse wire
has occurred and this rod may be made to effect the operation of an electromagnetic
device or other mechanism for giving a visual or an audible indication, or both, that
rupture of the fuse wire has occurred.
A visual or an audible indication, or both, of this fact may be afforded by a device
in which a rod moving by the force of a spring in a case attached to the outside of
the tube or case, is provided with a loop or hook, through which loop or hook
the fuse wire passes and when the fuse wire is intact, the rod is prevented from
moving, but when the fuse wire is ruptured the spring is allowed to act to move
the rod.
Other forms of devices operating to afford a visual or audible indication of the
rupture of the wire may be used.
In one form of the device the covering and indicating devices are not used.
For the purpose of removing the material produced by the fusion of the fuse wire,
perforations may be formed in the space of the tube or case normally closed by any
suitable means as for example by screws.
For the purpose of facilitating the re-use of the case or tube after the fuse wire
has been burned out, the outside case of the fuse is preferably made of fibre and is
closed at each end by blocks of fibre held by a ferrule of metal. The fuse wire passes
through a cylinder or inner fuse tube which is covered with a sheathing of asbestos.
Between partitions in this inner tube is placed a hollow cylinder of fibre which
encloses the air space. At each end of the inner tube and bearing against the asbestos

page_text: filling or packing is a disc of metal having notches therein. The fuse wire passes
through one notch, if the wire is small, but if large the fuse wire is in three strands,
each of which passes through a notch and is then brought against the disc thus
causing contact. The fibre block or end piece is then put against, the metal disc, the
ferrule applied and a metallic terminal inserted through perforations in the end piece
and serewed into the disc. These inner tubes are made, separately and when a fuse
wire is burnt out the inner tube is replaced by another having a perfect fuse wire,
or a fresh piece of fuse wire can be inserted into the inner tube and secured
therein. This enables the outer case to be filled with greater facility than if the fuse
is constructed as described previously.
A communication by GEORGE HARRIS GOODHUE, of Brookline, in the County of
Norfolk and State of Massachusetts, Merchant, and FERDINAND AUSTIN HART, of
Hartford in the County of Hartford, and State of Connecticut, Insurance Agent,
both of the United States of America.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of the Agency for Foreign
Patent Solicitors, 6, Lord Street, Liverpool, and 6, Bank Street, Manchester, both in
the County of Lancaster, 118, New Street, Birmingham, in the County of Warwick,
and 322, High Holborn, in the County of Middlesex, Civil Engineer, do hereby
declare the nature of this invention and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement :-
This invention relates to enclosed fuses and has for its object,
First. The production of a safety-fuse which when connected in a circuit can be
handled or touched, without the possibility of the person touching the device coming
into contact with any part of the circuit.
Second. The production of a safety-fuse which can be used in places where there
are inflammable or explosive gases or substances without the possibility of causing
the ignition or explosion of these gases or substances.
Third. The determination at a definite part of the fuse wire of the rupture of
the same by the fusing effect of the heat produced by the increased current through
the fuse wire.
Fourth. The prevention of noise when the fuse wire is ruptured by the effect of
the increased current.
Fifth. The prevention of the formation of an are at the point where the fuse wire
breaks.
Sixth. The absorption and distribution of the gases or other substances produced
by the fusing of the fuse wire whereby the force of any explosive action attending
this fusing is rendered harmless.
Seventh. The capability of removing from the enclosing tube or case the substance
produced by the fusing of the fuse wire.
Eighth. The regulation of the carrying capacity of the fuse wire whereby its
rupture by the fusing effect of the increasing current may be predetermined for any
strength of current and for any period of time.
Ninth. The production of means for obtaining with an enclosed fuse wire an
indication on the outside of the case that a rupture of the fuse wire has occurred.

page_text: These results are attained by the devices hereinafter described in this specification
and illustrated in the accompanying drawings and which devices embody the principle
of this invention.
In these,
Figure 1 is a longitudinal sectional view of one form of these devices and shows
the fuse wire as unbroken and the covering device held in position by the fuse-wire.
Figure 2 is a similar longitudinal sectional view of the same device and shows the
fuse wire broken and the covering device moved to cover the perforation in the
partition and to give an indication that a rupture of the fuse wire has occurred.
Figure 3 is a detached view in elevation of the covering device used in this
embodiment of the invention and shows the recess in the covering device.
Figure 4 is a detached sectional view of this covering device.
Figure 5 is an end view of the tube or case.
Figure 6 is a longitudinal sectional view of a part of another form of device
embodying the principle of the invention and shows another form of covering
device.
Figure 7 is a horizontal sectional view of-that part of the device which contains the
covering device.
Figure 8 is a plan view of the indicator operated by the covering device.
Figure 9 is a sectional longitudinal view of part of the device and shows another
form of covering device.
Figure 10 is a front view of this covering device showing its position when the
fuse-wire is unbroken.
J&-
Figure 11 is a sectional longitudinal view of part of the device and shows still
another form of covering device.
Figure 12 is a longitudinal sectional view of part of the device and shows a means
for giving an indication that the fuse wire is broken.
Figure 13.is a longitudinal view in elevation of the device without the indicating
device and of the means for supporting the device when in use.
Figure 14 is a longitudinal sectional view of the same.
•
Figure 15 is an end view of the same.
Figure 16 is a perspective view of a terminal.
In these several figures the same numerals refer to the same parts.
The fuse wire 2 passes through a tube or case 1, which fuse wire may be of the
usual form or material or of any suitable form or material. This case 1 may be
cylindrical or rectangular, or of any convenient form. It may be made of any suitable
material, but if made of a conducting material its ends should be of an insulating
material or insulation should be afforded for the terminals to which the fuse wire is
attached. A convenient material for the tube or case is fibre. A convenient size for
general purposes is about three inches in length by three quarters of an inch-in
diameter; as shown in the drawing, but it may be of larger or of smaller dimensions
as may be found desirable.
The ends of the tube or case 1 are closed and a convenient means of accomplishing
this result is by means of end pieces 3, each of which may be held in position by an
insulating ferrule 4, or in any other suitable manner. In each of the ends of the
tube or case is inserted a piece of metal 5, round or square in section, and in the
form of a rod or strip, or of any other convenient form. This piece may have in it
a longitudinal perforation for the reception of the fuse wire or the fuse wire may be
otherwise attached to the pieces 3.
This piece forms a suitable terminal for the fuse wire by means of which connection
of the fuse wire is made with the conducting wire of the circuit; as for example, by
the insertion of these terminals in suitable sockets in standards 7 supported upon a
suitable base-plate 8 to which standards the. conducting wires are connected in any
-suitable manner: These standards are best made of sufficient height-to prevent the
possibility of contact of the conducting wire with the-tube or case.
A boss 9 of insulating material may be placed upon the end of the tube or

page_text: case, in order to prevent contact of the tube or case with the support for the
conducting wire.
The inner ends of the terminals project into the adjacent filling and act to conduct
heat away from the fuse wire at that part of the same so as to prevent the possibility
of the fuse wire fusing near the end of the case.
These inner ends of the terminals are preferably tapered and split, as shown in
Figure 16, and the perforation for the insertion of the terminal in the end of the
tube or case is preferably tapered, as shown in Figure 14, so that after the terminal
is inserted, its inner end will be compressed to firmly bind the fuse wire and
ensure good contact with the same. Other forms of terminals may however be
employed such for instance where the fuse is replaced by wires and the ferrule
insulated.
Each end of the case is filled with some material different from the fuse wire
and acting to conduct away from that part of the fuse wire which passes through
this filling the heat produced by the passage of the current through the fuse wire.
Several substances can be used for the filling 10, as for example, asbestos, plaster-
of-Paris, oil, paraffin and my correspondents do not confine themselves to any
particular substance, provided it is different from the fuse-wire and acts to conduct
heat away from the same, but asbestos is preferred and a convenient manner for using
this material is by winding a strip of sheet asbestos around a part of the fuse wire
until such a thickness of covering is secured that when the asbestos covered wire is
inserted into the tube or case, the asbestos will be packed or firmly held in the end
of the tube or case.
Asbestos is insulating, is non-inflammable, is sufficiently heat conducting to conduct
some of the heat away from that part of the fuse wire which is in contact with the
asbestos and by its porous nature it acts to absorb and hold the gases and other
substances produced by the fusing and combustion of the fuse wire by the heat
produced by an increased current passing through the fuse wire, and by its elasticity
it yields to the pressure of the gases and thus in connection with the absorption of
the gases and other substances produced by the fusing and combustion of the fuse
wire tends to prevent harmful results from any explosive action when this fusing and
combustion takes place. It is also coherent and can be packed around the fuse so as
to enable a definite air space to be formed in the enclosing tube or case without the
use of a partition or of a drum.
Between each of the filled ends of the tube or case is a space 11 through which the
fuse wire passes and in order to ensure the rupture of a fuse wire of the same con-
ductivity by any predetermined strength of current, and after the passage of a
current for any predetermined time, this space must be of definite dimensions, as
any variation in the dimensions of this space will effect the carrying capacity of the
fuse wire to the point of rupture by an increased current, and it is important in
safety-fuses for electrical circuits that the carrying capacity of the safety-fuse should
be accurately known.
If the filling material is capable of being compacted into each end of the tube or
case, the definition, with accuracy, of the space 11 between the fillings 10, can be
effected without a partition but as some of the materials which may be used for
filling must be otherwise retained in the end of the tube or case there may be placed
between the filling and the space 11 a transverse inflexible partition 12 perforated
for the passage of the fuse wire but it is preferred to use partitions with any materials
as these partitions act to confine the force of the explosion to the air space and to
direct through the perforation in each partition the heated air, gases or other
substances generated when the fuse wire melts and thus to cause the blowing out of
any are which may be formed.
The proper insulation of the fuse wire in this partition is obtained either by making
this partition of an insulating material, or in any other suitable manner.
The partitions may be separable from the case, and they fit air-tight within the
same and they may be held in position in any suitable manner and be adjustable,

page_text: thus permitting a variation in the length of the air space for the purpose of changing
the carrying capacity of the fuse wire.
As the fuse wire in the space 11 between each of the filled ends of the tube or case
is out of contact with any heat-conducting material, rupture of the fuse wire by the
heat produced by the increased current passing through the fuse wire will take place
at the part of the fuse wire in the above-named space 11, instead of at any other part
of the fuse wire, and the gases or other materials produced by this fusing of the fuse
wire will be mainly formed in this space 11.
For the further purpose of preventing the passage of an arc from this space through
the perforation in the partition when the fuse wire is ruptured in this space 11, a
device may be made use of which is normally held in position by the fuse wire when
this fuse wire is unbroken against a force acting to move this device, which device
automatically covers the perforation in the partition when the fuse wire is ruptured,
and in this part of the tube or case is placed the means whereby an indication may
be given that the rupture of the fuse wire has occurred.
The means for giving this indication may form a part of the covering device and
may be operated thereby or it may be an independent device and either or both of
these devices may be dispensed with.
For giving this indication and for covering, various devices may be adopted.
In Figures 1 and 2 is shown the device for covering the perforations in the partition
through which the fuse wire passes which may consist of a block 13 of an insulating
material perforated for the passage of the fuse wire and held in position by the fuse
wire when the latter is intact, and moving transversely to the tube or case 1 in
substantial contact with or adjacent to the inside surface of the partition in a tube
formed by the partition, a collar 14 on the inside of the tube or case, and a rim 15 each
around opposite openings in the tube or case 1 on opposite sides of the same.
The ends of the transverse tube are each preferably covered with a cap 16 and one
or both ends of those caps may be removable in order that the block 13 can be
removed from the tube or case and thus permit the removal from the space 11 of
substances produced by the fusing of the fuse wire. On one end of the block 13 is
a rod or projection 17 which passes through a cap 16, and when the fuse is unbroken,
On the other end of the
is substantially normal to the outer surface of this cap.
block 13 a suitable spring is arranged which acts when said block is permitted to
move by the breaking of the fuse wire to move this block so that it covers the
perforation in the partition and also causes the projection from the surface of the
cap 16 of the rod or other device attached to the block 13, thus affording a visual
Instead of the rod 17 any
indication that a rupture of the fuse wire has occurred.
other suitable device may be used.
A helical spring 18 in a socket 19 in the block 13 has been shown, but it is obvious
that other forms or arrangements of springs may be used or any other means for
moving the block 13 on the release of the same.
A longitudinal recess 20 surrounding the fuse wire is preferably formed in the
block 13 open towards the space 11, between each of the filled ends of the tube or
case and tapering towards an adjacent partition 12. The effect of this recess is to
bring upon that part of the fuse wire which is near the perforation in the partition
the pressure of the spring, which moves the block 13 and thus causes a tendency of
the fuse wire to first rupture at that point when the fuse wire is softened by the heat
of the increased current.
'
This recess also acts to receive the gases produced when the fuse wire is fused
so that the block will have a tendency to be moved by the expansive force of these
gases.
The movement of the covering device produced when the block is released by
the rupture of the fuse wire may be made to open or close an electric circuit
for the purpose of operating electric magnetic devices for giving a visual or an
occurred,
audible indication, or both, that a rupture of the fuse wire has
the same
or it may be made to operate or release other mechanism for
purpose.

page_text: One, two or more covering devices may be used.
Instead of a perforation, a transverse slot may be used for the passage of the fuse
wire through the covering block.
In the covering device shown in Figures 6 and 7, the block 13 rotates in the
transverse tube, this rotation being effected by a suitable spring 21 or by any other
suitable means when the fuse wire breaks.
The visual indication may be given by the movement of an index 22 on the outside
of the tube or case and attached to the block.
"
The recess 20 acts to locate the point of rupture of the fuse wire near the
perforation in the partition.
In the device shown in Figures 9 and 10, the transverse tube is dispensed with and
on each end of the covering block 13 is a rod 23 which passes transversely through
the tube or case.
In the covering device shown in Figure 11, the fuse wire rests upon the end of
the block 13 and this block is bevelled off towards the partitions.
The withdrawal of the rod 24 attached to the block 13 and normally projecting
through the side of the tube or case, affords a visual indication that rupture of the
fuse wire has occurred and this rod may be made to effect the operation of an electro-.
magnetic device or other mechanism for giving a visual or an audible indication, or.
both, that rupture of the fuse wire has occurred.
1
A visual or an audible indication, or both, of this fact may be afforded by the
device shown in Figure 12 in which a rod 25 moving, by the force of a spring 26 in a
case 27 attached to the outside of the tube or case, is provided with a loop or.hook 28
through which loop or hook the fuse wire passes and when the fuse wire is intact, the
the rod 23 is prevented from moving, but when the fuse wire is ruptured the spring 26:
is allowed to act to move the rod.
4
L
• Other forms of devices operating to afford a visual or audible indication of the
rupture of the wire may be used.
1
4.1.
In the device shown in Figures 13 and 14, the covering and indicating devices are
not used.
:
. I
...
For the purpose of removing the material produced by the fusion of the fuse wire,
perforations 29 may be formed in the space 11 of the tube or case normally closed
by any suitable means as for example by screws 30.
For the purpose of facilitating the re-use of the case or tube 1 after the fuse wire
has been burned out, the outside case of the fuse is preferably made of fibre and is
The fuse wire
closed at each end by blocks of fibre held by a ferrule of metal 4.
asbestos.
The fuse wire
passes through a cylinder or inner fuse tube which is covered with a sheathing of
Between partitions in this inner tube is placed a hollow cylinder of fibre
which encloses the air space. At each end of the inner tube and bearing against the
asbestos filling or packing is a disc of metal 5 having notches therein.
passes through one notch, if the wire is small, but if large the fuse wire is in three
strands, each of which passes through a notch and is then brought against the disc
thus causing contact. The fibre block or end piece is then put against the metal
disc, the ferrule applied and a metallic terminal inserted through perforations in the
end piece and screwed into the disc. These inner tubes are made separately and
when a fuse wire is burnt out the inner tube is replaced by another, having a perfect
fuse wire, or a fresh piece of fuse wire can be inserted into the inner tube and secured
therein. This enables the outer case to be filled with greater facility than if the
fuse is constructed as described previously.
.Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, as communicated to
me by my foreign correspondents, I declare that I am aware of Moodey's Specifica-
tion No. 19076 A.D. 1890, and I do not claim anything described or claimed therein,;
but what I claim is :-
1. The combination, substantially as set forth, of an air-tight tube or case
enclosing the entire fusible metal and tightly closed at each end by an inflexible

page_text: material, a coherent packing at each end of the tube or case of a different
material from the fuse wire and acting to conduct away from that part of the fuse
wire which passes through the filling the heat produced by the passage of the
current through the fuse wire at that part, a definite air space between the
packings, and a fuse wire passing through the packings and air space.
2. The combination, substantially as set forth, of an air tight tube or case
enclosing the entire fusible metal and tightly closed at each end by inflexible
material, a packing of asbestos at each end of the tube or case, a definite air space
between the packings, and a fuse wire passing through the packing and the air
space.
3. The combination substantially as set forth, of an air tight tube or case enclosing
the entire fusible metal tightly closed at each end by inflexible material, transverse
inflexible partitions dividing the tube or case into sections of a definite length and
perforated solely where the fuse wire passes through the partition, a fuse wire passing
through the tube or case and partitions, a filling at each end of the tube or case of a
different material from the fuse wire and acting to conduct away from that part of
the fuse wire which passes through the filling the heat produced by the passage of
the current through the fuse wire at that part, and to absorb the gases and other
substances generated when the fuse wire melts, and a definite air space between
the end sections.
4. The combination, substantially as set forth, of an air tight tube or case, enclosing
the entire fusible metal and tightly closed at each end by inflexible material,
transverse inflexible movable partitions dividing the tube or case into sections
of a definite length and perforated solely where the fuse wire passes through the
partitions, a fuse wire passing through the tube or case and partitions, a filling
at each end of the tube or case of different material from the fuse wire and
acting to conduct away from that part of the fuse wire which passes through
the filling, the heat produced by the passage of the current through the fuse
wire at that part and to absorb the gases and other substances generated when the
fuse wire melts, and a definite air space between the end sections.
5. The combination, substantially as set forth, of a tube or case, a fuse wire passing
through said tube or case, a rod extending transversely through the case and normally
held by said fuse wire when said fuse wire is unbroken, and a spring acting when the
fuse wire is broken to cause the projection of the rod.
6. The combination, substantially as set forth, of a tube or case, a fuse wire
passing through said tube or case, a transverse partition in said tube or case, through
which partition the fuse wire passes, a movable device normally held in position by
the fuse wire when said fuse wire is unbroken, means acting when the fuse wire is
broken to move the device to cover the perforation in the partition through which
the fuse wire passes and means operated by the movement of the covering device to
give an indication that the fuse wire is broken.
7. The combination substantially as set forth, of a tube or case, a fuse wire passing
through said tube or case, a transverse partition in said tube or case through which
partition the fuse wire passes, a movable device adjacent to the inner surface of the
partition and through which device the fuse wire passes, and normally held in
position by the fuse wire when said fuse wire is unbroken and moving when the
wire is broken adjacent to the inner surface of the partition to cover the perforation
of the partition through which the fuse wire passes, and a perforated recess in this
device tapered towards the partition and surrounding the fuse wire.
8. The combination, substantially as set forth, of a tube or case, a fuse wire
passing through said tube or case, a transverse partition in said tube or case
through which partition the fuse wire passes, a block of insulated material perforated
for the passage of the fuse wire and adjacent to the inside surface of the partition and
transversely movable, a covered transverse tube for the movement of said block, a
spring acting to move said block transversely when the wire is broken in the space
adjacent to the inner surface of the partition and a device attached to the block and

page_text: projecting from the tube or case when the block moves on the rupture of the fuse
wire.
9. The combination, substantially as set forth, with an air tight tube or case
enclosing the entire fusible metal and tightly closed at each end by an inflexible
material, an insulated metallic terminal for the fuse wire and projecting respectively
from each end of the tube or case and extending within the same, supports for the
terminals, means for preventing the contact of the case with the supports, and
ferrules or caps on each end of the tube or case and insulated from the adjacent
terminals.
10. The combination, substantially as set forth, with an air tight tube or case
enclosing the entire fusible metal and tightly closed at each end by an inflexible
material, an insulated metallic terminal for the fuse wire and projecting respectively
from each end of the tube or case and extending within the same, supports for the
terminals, and insulating boss on the outside of each end of the tube or case for
preventing the contact of the case with the supports, and ferrules or caps on each
end of the tube or case and insulated from the adjacent terminals.
Dated this 5th day of Anil 1909
WM. P. THOMPSON & Co.,
Agents