Note: Descriptions are shown in the official language in which they were submitted.
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DEVICE FOR TIGHTENING CHAINS AND THE IJIKE
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Background of the Invention
1. Field of the Invention
The invention pertains to the field of devices such
as turnbuckles for tighteniny or takiny up slaak in
chains, cables, ropes and the like.
2. Description of the Prior Art
In many applications, it is necessary to tighten or
take up the slaclc in a chain, cable or rope particularly
by drawing the two ends of the chain together around an
object, or drawing together the ends of two chains whose
ends are secured. Typically this has been done in the
past by securing each end of the chain or cable or the
ends of two chains or cables to the opposite ends of a
turnbuckle and rotating the sleeve of the turnbuckle by
hand. the amount of tensioning which can be accomplish-
ed by hand can be increased through the principle of the
lever by inserting a bar or screwdriver through the
opening in the turnbuckle and applying pressure at the
end ox khe bar to rotate the sleeve. However, the
amount of tension which can be applied in this manner is
clearly limited.
For example, in a body shop environment, chains
are commonly used to tie down the damaged vehicle while
it is mounted on a stand and secure it so that work may
be performed on the vehicle without the danger of the
vehicle falling off the stand. At present, such chains
are tightened using a turnbuckle but sufficient tension
to maintain the vehicle in a rigid position cannot be
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obtained through hand-tightening of the turnbuckle.
Similarly, loads on a truck or boat are often tied down
using chains. In this application, load binders are
often used to tighten the chain. These binders work on
the principle of the lever and are locked in the closed
position when the point of rotation passes through a
point of highest tension into a rest position of slight-
ly lower tension. This serves to retain the load binder
in the closed pos;tion. However, because of the slight
slacXening involved in this locking method and because
they are applied by hand, such binders cannot secure the
chain under extreme tension.
Summary of the Invention
The present invention provides a device for tighten-
ing chains and the like which comprises an elongate
threaded bolt element which is secured to a fixed end of
a chain, a sleeve element to which a second retractable
end oE a chain is secured and which receives the bolt
and attached chain and which prevents rotation o the
chain, and jeans for threadably receiving the bolt ele-
ment and drawing it throuyh the sleeve element. In the
preerred eorm, the means for threadably receiving the
bolt element consists of a threaded ~ocke-t having a hex-
agonal end which can be kurned using a wrench or air-
gun. Further in one aspect of the invention, the bolt
i8 provided with a stopper which prevents it from fall-
ing completely out of the sleeve. Further according to
one aspect of the invention, a short length of chain is
welded to the bolt element 90 that a hook or other means
may be used to connect the device to the end of the
chain or cable to be tightened. According to yet an-
other aspect of the invention the acute angle formed
between the device and the chain being shortened is
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minimized. Conversely, the obtuse angle formed by the
device and the chain is maximized. The component of
force applied along the chain to be tightened is thereby
maximized. according to a further aspect of the inven-
tion, a hydraulic cylinder may be utilized to draw the
chain into the sleeve, rather than a threaded bolt. In
this embodiment, the sLeeve need not prevent the rota-
tion of the chain.
Brief Description of the Drawings
In drawings which illustrate an embodiment of the
invention,
Figure 1 is a perspective view showing the device
of the present invention in disassembled form wi-th chain
attached;
Figure 2 is a perspective view showing the device
illustrated in Figure 1 in an assembled state; and
Figure 3 is a side view of the device illustrated
in Figure 1 cut away along lines A - A to show the inte-
rior of the device in cross-section.
Description of a Preferred Embodiment
Referring t.o Figure 1, the chain-tightening device
consists ox three central components: a threaded bolt
element 1, a hollow elongated sleeve 2 and a socket 3
into which a bolt 1 is threaded. The lengths of bolt 1
and socket element 3 are chosen according to the amount
of shortening required to be carried out by the device.
One end of bolt 1 is attached to a flexible linkage such
as by welding (as at 4~ onto a short length of cable or
chain 5. Chain 5 may then be secured to the first re-
tractable end of the length of chain to be tightened
using conventional means such as a hook or clip (not
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shown). Other means may be used to secure the end o
bolt 1 to the chain or cable to be tightened, such as by
providing the end of -the bolt with an eye or hook.
were a length of chain 5 is used as shown in Figure 1,
the chain must be somewhat longer than sleeve 2 so that
the travel of the bolt will not be interrupted by con-
tact between the hook at the end of chain 5 and the
sleeve 2. Bolt 1 is provided at one end with a circular
stopper 6 which will be further described below.
Sleeve 2 consists of a hollow tube having an open
end 7 and a circular opening 8 at the other end through
which bolt 1 passes. Where the device is used to tigh-
ten chain, the sleeve is preferably rectangular in
cross-section and so dimensioned that the chain is pre-
vented from turning within the sleeve. Preferably the
sleeve is constructed from heavy metal tubing and open-
ing 8 may be formed by welding a metal washer to the end
of the tube. Sleeve 2 has a pair o flanges or lobes 9
attached to its lower side adjacent opening 8. These
are provided with holes 10 to receive pin 11. The end
of the chaln to be tightened 12 is secured to the sleeve
2 by means of pin 11. PreEerably, pin 11 i5 located 30
that the Eixed end oE the chain i8 aligned to form a
180 angle with the retractable end of the chain where
it enter sleeve 2. Flanges 9 are configured so that
sleeve 2 iB offset with respect to the chain to be
tightened to allow access to the device with a power
tool, and to maximize the effective tensioning Eorce.
In constructing the preferred form of the device,
bolt 1 must be inserted through aperture 8 and washer 16
and threaded element 13 threaded onto the bolt before
stopper 6 has been welded to the end of the bolt. Once
stopper 6 has been attached, socket element 14 is secu-
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red to threaded element 13 by welding at 17 (see Figure
3).
Referring to Figure 3, bolt 1 is drawn through hole
8 by the action of threaded socket 3. Socket 3 has
threaded end 13 which mates with the threads of bolt 1.
The end of bolt 1 travels into a hollow socket portion
14 of element 3 which has at one end a hexagonal projec-
tion 15 suited to be turned by a wrench or air-gun.
Washer 16 may be interposed between element 3 and sleeve
2 in order to increase the durability of the device.
Operation of the device may be understood by refer-
ring to Figure 3. Chain 5 is secured to the first re-
tractable end of chain by a hook or other means. Where
a single chain is being tightened around an object, the
second end of chain 12 is passed around the load or
structure to be secured and is then attached to flanges
9 by passing pin 11 through the end link 19. Where two
chains are being drawn together, the end of thy fixed
chain 12 is similarly attached by means of pin 11. An
air-gun or other power operated or hand-operated wrench
is then applied to end 15 to turn the socket element 3.
'rhe action o threaded element 13 rotating on bolt 1
causes the bolt to be drawn into socket element 3 which
bears against washer 16. Chain 5 is prevented from ro-
tating within the sleeve by the shape and dimension of
sleeve 2. As socket 3 is rotated, the retractable end
of chain secured to linkage 5 is drawn towards fixed end
12 and the chain is tightened. It has been found that
using a 3/8th inch chain and an air-gun to turn nut 15,
a tension on the order of 2 tons can be applied to the
chain.
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An impor-tant feature of the invention which permits
high tension to be applied to the chain or cable is the
fact, illustratad in figure 3, that the ends of the
chain 12 remain substantially aligned as the chain is
being tightened, and the angle B is minimized. By mini-
mizing angle B, (or, conversely, maximizing angle D),
while maintaining enough clearance be-tween the chain and
socket element 3 to permit access to the device for
tightening with a power tool, the component oE the
applied force F which lies along the direction of the
chain, indica-ted as C, is maximized. Consequently the
applied force is translated most efEiciently into ten-
sion along the chain and higher tension may be achieved.
In a second embodiment of the invention, hydraulic
Eorce may be substituted for the screw action shown in
the embodiment illustrated. In this embodiment, a
smooth shaEt of circular cross-section is substituted
for the threaded bolt 1. The shaft would enter a hy-
draulic cylinder corresponding to socket element 3
through a sealed aperture. The end of the shaft would
be provided with a piston (in a location similar to that
ox stopper 6). Hydraulic ~luicl under pressure would be
provided to the cylinder at location 20 in Figure 3,
thereby driving khe piston and drawing chain 5 into the
sleeve, tightening the chain. In this embodiment, it
would not be necessary to prevent chain 5 Erom turning
within the sleeve, and accordingly a rectangular sleeve
would not necessarily be preferred Eor chain tightening.
The embodiment illustrated has been designed for
tightening 3/8th-inch chain and accordingly is shown as
being constructed of strong and durable materials. The
principle of the invention may be applied to the tight-
ening o-E lighter chains, cables or ropes, in which case
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less durahle materials might be substituted. For exam-
ple, a smaller cable might be subskituted for chain 5.
In that case, the cable or rope would be provided with
means to prevent rotation within the sleeve 2. Also,
stopper 6 may be dispensed with without reducing the
utility of the invention and the use o-f washer 16 is not
necessary to the invention. A standard nut could be
substituted for socket element 3 if the device was only
to be hand tightened. As will be apparent to persons
skilled in the art, various other modifications and
adaptations of the structure above described are possi-
ble without departure from the spirit of the invention,
the scope of which is defined in the appended claims.
