IMPROVEMENTS IN CHAINS FOR SUSPENSION BRIDGES AND OTHER STRUCTURES REQUIRING CHAINS, EITHER FOR SUSPENSION OR BRACING
Year: 1879

page_text: LETTERS PATENT to Sir William George Armstrong, of Elswick Works, New-
castle upon Tyne, Knight, C.B., for the Invention of "IMPROVEMENTS IN
CHAINS FOR SUSPENSION BRIDGES AND OTHER STRUCTURES REQUIRING CHAINS,
EITHER FOR SUSPENSION OR BRACING."
Sealed the 1st July 1879, and dated the 21st January 1879.
PROVISIONAL SPECIFICATION left by the said Sir William George Arm-
strong at the Office of the Commissioners of Patents on the 21st January
1879.
Sir WILLIAM GEORGE ARMSTRONG, of Elswick Works, Newcastle upon Tyne,
Knight, C.B.
"IMPROVEMENTS IN CHAINS FOR SUSPENSION BRIDGES AND OTHER
STRUCTURES REQUIRING CHAINS, EITHER FOR SUSPENSION OR BRACING."
This Invention has for its object-improvements in chains for suspension bridges
and other structures requiring chains, either for suspension or bracing.
I roll the bar for each link of steel or iron in a continuous circle by a process
similar to that which is used for rolling continuous wheel tyres, and I then flatten
the circle so as to bring it into the form of a link with its sides parallel to each
other, and its ends rounded to correspond on the inuer surface with the diameter of
the connecting pin or bolt. The links are brought to the exact length required by
stretching them by hydraulic or other power to a standard gauge of length. The
object of this mode of construction is to make a chain of endless bars without
welds, and having the longitudinal fibre of the material lying in the most favourable
direction, both at the sides and ends of each link. The links are formed into a
chain by arranging them side by side with interposing ends, and passing a con-
necting bolt through them, so that each successive link shall bear against opposite
sides of the bolt.
This method of manufacture admits of the use of qualities of metal in which
links cannot be securely and advantageously closed by welding.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Sir William George Armstrong in the Great Seal Patent Office on
the 21st July 1879.
Sir WILLIAM GEORGE ARMSTRONG, of Elswick Works, Newcastle upon Tyne,
Knight, C.B. "IMPROVEMENTS IN CHAINS FOR SUSPENSION BRIDGES AND OTHER
STRUCTURES REQUIRING CHAINS, EITHER FOR SUSPENSION OR BRACING."
This Invention has for its object improvements in chains for suspension bridges
and other structures requiring chains, either for suspension or bracing.
I roll the bar for each link of steel or iron in a continuous circle by a process
similar to that which is used for rolling continuous wheel tyres.
The system of rolling continuous weldless circles of steel and iron being well
understood and in extensive use it is unnecessary that it should be here described.
The circle may be made of any convenient size, and the larger the better, con-
sistently with the chain having the pliability requisite for the purpose for which it
is intended. I then flatten the circle so as to bring it into the form of a link with
its sides parallel to each other, and its ends rounded to correspond on the inner
surface with the diameter of the connecting pin or bolt.
I prefer to flatten the circle by pressing the sides inwards, whilst at the same
time the circle is distended between two pins or bolts of the same diameter as the
pins to be used in making up the chain. This operation is best performed whilst
the metal is hot, and care should be taken to avoid as far as possible alteration in
the sectional form of the metal.
The links are afterwards brought to the exact length required by stretching them
by hydraulic or other power to a standard gauge of length. This may be done
either hot or cold; if hot, the links should remain in the stretcher until cold. The
links should be supported whilst exposed to the strain by a block inserted into
them of a thickness equal to the diameter of the pins. If care be taken in rolling
the circles only a small amount of extension will be required to adjust them to the
standard size.
The object of this mode of construction is to make a chain of endless bars with-
out welds, and having the longitudinal fibre of the material lying in the most
favorable direction, both at the sides and ends of each link. The links are formed
into a chain by arranging them side by side with interposing ends, and passing a
connecting bolt through them, so that each successive link shall bear against
opposite sides of the bolt.
To form a symmetrical chain an odd and an even number of links may be em-
ployed alternately, and the links may be varied in transverse section so as to afford
the required tensile strength in each set.
In chains for suspension bridges in general the strength of the chain would
diminish from the pier to the centre of the span.
The pins should be of such a size as to ensure rigidity and avoid excessivo
pressure in the bearing parts. The projecting ends of the pins may receive screw
nuts. The annexed Drawing represents a portion of such a chain with the pin and
links suitably proportioned.
This method of manufacture admits of the use of qualities of metal in which
links cannot be securely and advantageously closed by welding.

page_text: What I claim is, the construction of chains with links produced from continuous
weldless circles of steel or iron, substantially in the manner described.
In witness whereof, I, the said Sir William George Armstrong, have here-
unto set my hand and seal, this Fifteenth day of July, in the year of our
Lord One thousand eight hundred and seventy nine.
W. G. ARMSTRONG. (LS)