Improvements in the Construction of Pitch Chains.
Year: 1892

page_text: Date of Application, 13th July, 1892-Accepted, 13th Aug., 1892
COMPLETE
SPECIFICATION.
[Communicated from abroad by THOMAS GIBSON MCLELLAND, of Beaconsfield,
Griqualand West, Cape Colony, Mining and Mechanical Engineer.]
Improvements in the Construction of Pitch Chains.
I, DANIEL FRANCIS, of 191 Gresham House, Old Broad Street, in the City of
London, Gentleman, do hereby declare the nature of the said invention, and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement, reference being had to the accompanying sheet
of drawings, and to the letters and figures marked thereon, that is to say :-
This invention relates to improvements in certain kinds of pitch chains in which
the parts which are subject to great wear and tear are made in the form of bushes
which can easily be renewed or replaced without skilled labour, and the said
improvements consist in making the said renewable bushes of an eccentric shape
having the side which is to be subjected to the wear and tear of the teeth of the
driving wheel or drum preferably thicker than the opposite side, also in forming
the said bush with a flat on one side to prevent it from turning round in the chain-
link, and further in constructing the brush and the holes and shell of the link, in
which it fits, slightly taper, so that the bush, when driven into the said holes and
shell of the link, fits snugly and without shake therein.
And in order that the said invention may be fully understood, I will now proceed
to describe the same with the aid of the aforesaid sheet of drawings in which
Figure 1 is a plan, partly in section, of a portion of a pitch chain of ordinary
construction, but with the aforesaid improvements applied thereto,
Figure 2 is a sectional elevation taken on line A-B of Figure 1, and
Figures 3 and 4 are respectively a plan and elevation of the aforesaid eccentric
bush separate from the link.
The links of the chain are each composed, as usual, of two sides E E and a
hollow shell or end piece E' coupling the two sides E E together, the said sides and
shell or end piece being preferably made in one casting of iron, steel or other
suitable metal. F is the removable or renewable eccentric bush which is preferably
tapered lengthwise and is driven through corresponding holes in the eyes E² E² of
the link and lays in the hollow shell or end piece E. The bush F is preferably
of circular section as shown, but having a flat side F', and the holes in the eyes E² E'
of the link and the internal surface of the shell E' are shaped to correspond, so that
the bush F cannot turn therein. The bush may be concentric with the eyes of the
link, and the pin G which passes through it and connects the links of the chain
together may be eccentric with the said eyes and the said bush, as shown in the
drawings, or the bush may be eccentric with the eyes of the link and the pin G
concentric with the said eyes, or the bush and pin may be placed in any convenient
positions with regard to the eyes of the link provided always that the thicker part
of the bush is placed so as to come in contact with the actuating or propelling tooth.
The extra thickness of the bush at that side enables the said bush to be subjected
to considerable wear and tear before it is rendered useless. If preferred, the hollow
shell or end piece E' may be extended, as shewn in dotted lines at E* in Figure 2,
so as to embrace a greater portion of the circumference of the bush F.
The bushes are preferably made of hard material such as steel for example whilst
the links may be of softer material as they are not subject to such severe wear and
tear as the bushes.
The links may have cast to them and to their shells or connecting pieces any of
the usual brackets or fixings for carrying buckets, pallets or other parts as shown
at H for example in Figures 1 and 2.
By making the bushes eccentric with reference to the pins G that is to say by making

page_text: the wearing side of each bush thicker than the other side, the said bushes last very
much longer than when they are made concentric with such pins as heretofore, that
is to say of the same thickness on the wearing side as on the other. The shaping
of the bushes and the holes in the eyes of the links and the shell or connecting piece
through which they pass with a flat side is also a simpler and more economical method
of preventing the bushes from turning round than the method, heretofore adopted;
and the tapering of the bushes and of the holes in the eyes of the links and of the
internal surfaces of the shells or connecting pieces, facilitates the placing of the
bushes in position in, and their removal from, the links, while it enables them to be
driven in so as to be a tight and steady fit in the said holes and shells, a condition that
cannot be secured when the bushes are cylindrical.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
First. The improvement in the construction of pitch chains which consists in
making the removable or renewable bushes eccentric to the connecting pins, that is
to say thicker on the wearing side than on the opposite side, substantially as herein-
before described, and illustrated in the drawings and for the purpose specified.
Second. The improvement in the construction of pitch chains which consists in
making the removable or renewable bushes and the holes in the eyes of the chain
links through which the said bushes pass with a flat side, substantially as hereinbefore
described, and illustrated in the drawings, and for the purpose specified.
Third. The improvement in the construction of pitch chains which consists in
making the removable or renewable bushes tapering lengthwise, and in making the
holes in the eyes of the chain links and the internal surface of the shell or con-
necting piece with a corresponding taper as hereinbefore described, and illustrated
in the drawings and for the purposes specified.
Dated this 9th dow of Lul 1909
D. FRANCIS,
Per W. H. Beck,
115, Cannon Street, London, E.C., Agent:
D. FRANCIS,
Per W. H. Beck,
115, Cannon Street, London, E.C., Agent: