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Патент USA US3061026

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Oct. 30, 1962
Filed Dec. 14. 1959
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FIG. 2
611-14., 5W v M
United States Patent 0
Patented Oct. 30., 1962
Willis K. Hodgman, Jr., Taunton, Mass, assignor to
Hodgman Manufacturing Co., Inc., Taunton, Mass., a
_ _
corporation of Massachusetts
Filed Dec. 14, 1959, Ser. No. 859,413
1 Claim. (Cl. 169-42)
de?nitely predetermined distances from the plane of the
?at abuting inner surfaces of the link plates. The object
of this construction is to provide a de?nite turning mo
ment or tilting to the fulcrum-block since the bearing
surfaces of the fulcrum-block edges make contact with
the adjacent sides of the channels in the link plates on
opposite sides of the plane of the inside surfaces of the
link plates.
This invention relates to improvements in fusible links
The resulting tendency of the link plates to be thrown
used in automatic sprinklers for extinguishing ?res, or 10 apart when the solder melts is in the ratio of between
in other devices wherein it is desirable to hold certain
the limit-s 5 to l and 10 to 1. That is, if a pressure equal
parts of the mechanism to which they are applied in
to 1 unit is imposed on the assembled unsoldered link to
assembled condition until a predetermined degree of tem
hold the plates together, it takes a longitudinal pull ap
perature exists in the vicinity of the apparatus and melts
plied at the apertures 7 of from 5 to 10 units to rock the
the solder uniting the parts of the links.
15 fulcrum-block thereby throwing the link plates apart.
The objects of the invention are to provide a fusible
When the link is assembled the channels in the plates
link of superior e?iciency as to both its holding and re
and the fulcrum-block is mounted in that portion
leasing functions.
I attain these objects, in a fusible link of the three
of the chamber formed by the overlapped portions of
the channels. The fulcrum-block 6, it will be noted, is
symmetrical with respect to a plane extending midway
the thickness of the block. Hence the fulcrum-block
transverse channels, substantially rectangular in cross
may be placed in position with either edge up or down
section, which provide a chamber between the plates
and with either longer face against the bottom of either
which is occupied by a fulcrum-block located half and
channel. The fulcrum-block is thus reversible both edge
half in each of the plates. The sides of the channels are 25 wise and endwise. This is of material advantage in as
made with the edges bevelled or rounded and may have
suring the correct assembly of the link because it is im
rounded ?llets where they join the bottoms of the chan
possible by reason of this symmetrical form of the ful
nels. These radii are su?iciently small so that a straight
crum-block to place it in the wrong position.
portion is left on both sides of the channels, these straight
In addition, it will be noted that the radii of the corner
portions being substantially perpendicular to the common
edges 4a and 5a of the channels 10 are easily controlled
plane of the opposed plates. The fulcrum-block is sub
to close tolerances and that their contour permits long
stantially rectangular in cross-section and also has bevelled
wear for stamping dies employed in fabricating them.
or rounded edges, the radii of which do not have a com
Thus, since it is the distance from the plane of abutment
mon meeting point.
between the plates 4 and 5 to the point of contact with the
In order that the principle of the invention may be
fulcrum-block 6 which determines the wedging apart
readily understood, I have disclosed a single type or em
leverage of the link, and since this distance is determined
bodiment thereof in the accompanying drawing, in which:
by these radii, this exact control feature adds to the de
FIG. 1 is a side elevation of my link;
sirability of using this construction set forth herein. The
piece type embodying the principle of the invention, by
employing two opposed plates having relatively shoal
FIG. 2, a vertical section on line 2—2 of FIG. 1; and
edges 4a and 5a need not be round but can be bevelled
FIG. 3 is a magni?ed view of the central portion of 40 or faired and I shall use the term “truncated” in the
FIG. 2.
claim to de?ne any such equivalents generically.
Similar numerals refer to similar parts throughout the
It will also be noted that rounding the corner edges 6a
several views.
of the fulcrum-block 6, permits a free tilting of the block
My fusible link, as shown in the drawing, is of the three
6 which would otherwise be hindered by friction, surface
piece type and consists of duplicate plates 4 and 5, a 4-5 tension and/ or a suction effect of the liquid solder if the
fulcrum-block 6 and a fusible solder which melts at a
corner edges 6a were sharp.
predetermined degree of heat. The solder is applied be
With the link assembled and the parts soldered together,
tween the opposed surfaces of the parts of the link in the
the longitudinal pull applied at apertures 7 is taken mostly
usual manner but is not shown in the drawing.
by the fulcrum-block thereby producing a link of great
Each of the plates is provided, near its outer end, with 50 holding power until the solder is melted or fused by heat.
an aperture 7 to receive one of the parts to be held in
When this takes place, the fulcrum-block tilts and insures
assembled condition, shown in the drawing as the end
the immediate separation of the plates so that the link
of one of the levers 8 or 9 (shown in FIG. 2, only) of a
falls apart at once.
usual type of automatic sprinkler (not shown).
Having thus described one illustrative embodiment of
The inside face of each plate about midway of its length 55 my invention, I desire it to be understood that although
is provided with a transverse channel 10, of an approxi
mately rectangular cross section with the ?at parts of its
sides perpendicular or nearly perpendicular to the face
of the plate. The edges of these channels are bevelled
speci?c terms are employed, they are used in a generic
‘and descriptive sense and not for purposes of limitation,
the scope of the invention being set forth in the following
I claim:
?llets where the sides join the bottom of the channel. In
In a fusible link having identical link plates disposed
the drawings, these latter corners are shown, however,
in assembled condition in face to face relationship and
as perpendicular.
sealed together by a fusible material; a substantially rec
The fulcrum-block 6 is of slightly less width over all
tangular transverse channel formed in each said plate,
than the width of each channel 10 thus being free to tilt 65 said channels being opposed to each other when said
and pry the plates 4 and 5 apart when the solder melts,
plates are in assembled condition; each said channel hav
and has rounded corner edges as shown at 6a. The thick
ing a top wall and a bottom wall, each said wall being
ness of the fulcrum-block is twice the depth of each chan~
normal to the face of said plate, and a side wall parallel
nel so it is normally located half and half in the chan
to said face of said plate joining said top wall and said
nels. The rounded or bevelled edges 6a of the fulcrum
bottom wall; said substantially rectangular transverse
block are relatively short and leave opposed ?at surfaces,
channels being provided with rounded edges formed at
indicated at 11 in FIG. 3, bearing against each other at
the juncture of said top wall and said bottom wall with
or rounded as shown at 4a and 5a and may have rounded 60
the said face of said plate, said rounded edges extending
only a slight distance along the adjacent surfaces; and
further including a fulcrum block normally residing With
in said opposed channels, said fulcrum block being, sub
stantially rectangular in cross-section and having a sub
stantially ?at top face, a substantially flat bottom face,
a ?rst side face, and a second side face, said top and
said bottom faces being parallel to each other and said
?rst and said second side faces being parallel to each
other; said fulcrum block further having rounded edges
and being of substantially the same width as the com
bined width of said channels to abut said sides of said
channels at said ?rst and said second side faces of said
fulcrum block and further having a vertical dimension
such that said top wall of one of said channels abuts said 15
substantially ?at top of said fulcrum block and said bot
tom Wall of said other of said channels abuts said sub
stantially ?at bottom of said fulcrum block, said points
of abutment being in each instance inwardly in said chan
me] from said rounded edge thereof and inwardly on said
fulcrum block from said rounded edge thereof, whereby
when said fusible link is in assembled condition and a
force is exerted on said link plates along the center line
of the plane of said abutting faces thereof to draw said
plates apart, said force will be exerted upon said fulcrum
block through said link plates at portions of said top and
of said bottom of said fulcrum block spaced off center on
opposite sides of the center line of said fulcrum block to
impart a turning moment to said fulcrum block to cause
instant separation of said link plates upon melting of said
fusible material.
References Cited in the ?le of this patent
Shaw et a1 ____________ __ Apr. 14, 1903
Cook ________________ __ Oct. 5, 1915
Hopkins _____________ __ July 1,
Hopkins ____________ __ Oct. 26,
Nacy _______________ __ Apr. 24,
Hodgman ____________ __ Dec. 30,
Hodgman ____________ __ May 26,
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