IMPROVEMENTS IN PITCH CHAINS
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by the said Arthur Herbert Wallis at
the Office of the Commissioners of Patents on the 15th September 1881.
ARTHUR HERBERT WALLIS, of Basingstoke, in the County of Hants.
"IMPROVEMENTS IN PITCH CHAINS."
My Invention relates to a construction of pitch chain, such as is employed for
driving one wheel from another, or for elevating, dredging, and the like operations,
the object of my Invention being to provide a chain consisting of equal and
symmetrical links that can be readily put together or taken apart, these links
being secured against lateral opening resulting from strain, and when desired,
being provided with means of taking up slackness resulting from wear. For this
purpose I make each link in the form of a fork, having at one end a middle boss
with a transverse hole through it to receive a round pin. At the other end, in
each fork, there is a longitudinally slotted hole, each hole having at either side
or at each side an internally projecting rib extending partly along the slotted
hole. The pin for connecting two links is cylindrical, but is notched near each
end with notches to fit the internal ribs of the slotted holes above mentioned.
In putting together two links, the middle boss of the one is introduced between
the fork ends of the other, the pin is passed through, and then the links being
drawn a little apart, the notches near the ends of the pins become engaged on the
inwardly projecting ribs in the slotted holes of the forks. The pin is prevented by
these from turning in the forks, and also from shifting in the direction of its
length. Moreover, the notches of the pin being engaged on the ribs of the forks
prevent the forks from being spread laterally by the strain to which the chain may
be exposed. As the pin can turn only in the middle boss of the link, the wear is
only in the hole of that boss. To provide for such wear I fit the middle boss when
desired with a half bush, which, when worn, can be removed, and a fresh bush
being inserted in its place.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Arthur Herbert Wallis in the Great Seal Patent Office on the
8th March 1882.
ARTHUR HERBERT WALLIS, of Basingstoke, in
"IMPROVEMENTS IN PITCH CHAINS."
the County of Hants.
My Invention relates to a construction of pitch chain, such as is employed for
driving one wheel from another, or for elevating, dredging, and the like operations,
the object of my Invention being to provide a chain consisting of equal and
symmetrical links that can be readily put together or taken apart, these links
being secured against lateral opening resulting from strain, and when desired,
being provided with means of taking up slackness resulting from wear.
I will describe the construction which I adopt for this purpose, referring to the
accompanying Drawings. Fig. 1 is a front view of part of a chain according to
my Invention, with one of the joints shewn in section; Fig. 2 is a transverse
section of the joint, and Fig. 3 is a side view with part of one of the links turned
at right angles to the line of chain; Fig. 4 is a side view of the boss of a link
shewing how it may be bushed to provide for wear. Each link consists of a
tubular boss A with two fork arms B, B, projecting from it. Through the boss A
there is a plain round hole to receive a round pin C. In the two forks B, B, there
are slotted or elongated holes, and each of these holes has next its inner face
internally projecting ribs c which extend from the front end of the slotted hole
about half way backwards. The pin C is notched at its sides, each notch being of
such size and shape as to admit one of the ribs c. In putting the links together,
each link is turned at right angles or nearly so to the other (as indicated in respect
of the link B' at the right hand of Fig. 3), and pushed forward, its one side being
guided along the shoulder b of tlie next link; the pin C can then be introduced
behind the projecting ribs c, c, of the slotted holes in B', and then B' being drawn
backwards the ribs c, c, enter the notches of the pin C, whereupon the link B¹ is
turned so as to lie in a straight line or nearly so with B. In this condition of the
links the pin C cannot move lengthwise, being held by the ribs c engaged in its
notches, nor can the forks B, B, be opened apart by undue strain as the shoulders
of the notches of the pin C hold them in position. Moreover, the notched part of
the pin C being held by the ribs c, c, as in a wrench, is compelled to turn along
with the forks of the one link in the hole of the boss A of the next link, and thus
the wear of the pin and its bearing is distributed over the long cylindrical surface
in A. In cases where it is desirable to take up excessive slack resulting from wear,
the hole in the boss A may be elongated to partly hexagonal form, as shewn in
Fig. 4, and a partly hexagonal bush D can be introduced to take the wear of the
pin, a fresh bush being inserted in place of a previous bush when worn. Such
bushes may obviously be made of other than hexagonal form, provided they be of
such shape that they cannot turn in the hole. Also, instead of providing two
ribs c, c, in each slotted hole of the forks B, there may be only a single rib at one
side of each hole engaging in a single notch of the pin C, and the notch or notches
of the pin might be variously shaped. It is of advantage to make them
symmetrical, so that the pin fits either way, and that when one side of it is worn
it can be turned half round. As in the use of chains of this kind, the links are
never turned so far as to stand at right angles to each other, like B', Fig. 3, the
pins C cannot come out in working, the shoulders b of the one link preventing the
forks of the next link from shifting forward, so as to let the notched pin pass clear
of the ribs c, c, but when it is required to take the chain apart, a link can be turned
to the altitude of B', and shifted forwards, and thereupon the pin C can be taken
out.

page_text: Having thus described the nature of my Invention, and in what manner the same
is to be performed, I claim,-
First. The construction of a pitch chain, each link of which has a boss to receive
a round pin, and forks with elongated holes made with internally projecting ribs
engaging notches of the pin, substantially as and for the purposes set forth.
Second. In a pitch chain of the kind referred to in the preceding Claim, the use
as described of bushes D in the bosses A, to take the wear of the pins C.
In witness whereof, I, the said Arthur Herbert Wallis, have hereunto set my
hand and seal, this Fourth day of March, in the year of our Lord One
thousand eight hundred and eighty two.
ARTHUR HERBERT WALLIS. (L.S.)