Improvements in Sprocket Wheels.
Year: 1897

page_text: Date of Application, 9th Mar., 1897-Accepted, 10th Apr., 1897
Dtreet, Gleveland, ♥mo, in the United States in 11
Improvements in Sprocket Wheels.
I, CHARLES JUNGE, of Lincoln Chambers, 75 Chancery Lane, London, W.C.,
Consulting Engineer, do hereby declare the nature of this invention and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement :-
My invention relates to sheet metal sprocket wheels, the chief object being to
provide a neat and strong sprocket wheel which shall be very cheap.
The invention consists in a sprocket wheel, the outer portion of which consists of
a single piece of sheet metal comprising a single thick web part and a double thick
rim part which is formed by drawing the outer part or edge of said rim over and
into parallel relation to and in contact with the inner part thereof, and a spider
connected with the single thick web part substantially in the manner shown and
described herein.
In the drawing,
Figure 1 is a plan view of a complete sprocket wheel containing all of the
features of my invention embodied in what I believe to be the best and most
practical form.
Figure 2 is a sectional view of a part of said wheel on line 2-2 of Figure 1.
Figure 3 is a similar section of a slightly modified construction.
The web B and rim A of the sprocket wheel are integral with each other, and
are formed of sheet metal, preferably steel. The rim is made entirely of two
thicknesses of the metal, which are integral with each other, the connecting loops
being at the outer edge of the finished teeth.
In making the wheel shown, a circular blank of sheet metal is provided; and the
outer edge a of this blank is drawn over and inward by suitable dies, (the
construction of which will be understood by those skilled in the art), into parallel
relation, and into close contact with the adjacent parts of the blank, wherefore the
two thicknesses of metal which compose the rim are integral with each other, and
the loop or band which unites them is at the outer edge of the finished rim.
The teeth a' may be formed by milling or punching out the metal between them
from the outer edge of the rim.
An opening, which is preferably cylindrical, or approximately so, is punched out
of the blank, and a single thick portion is thus left extending inward from the rim
part, which I call the web. The size of the hole punched out and the amount of
web thereby left may be varied as the conditions render desirable. The ends of
the spider are bolted substantially as shown, to the single thick web part, and
thus the wheel is completed. In constructing sprocket wheels intended for use on
the crank axle of a bicycle, for which use they are admirably adapted,-I prefer
to make the central opening about two and one-half inches in diameter, irrespective
of the number of teeth or diameter of the rim. When various sized sprocket
wheels are thus constructed, any one of them may be connected with the same
spider C to change the gear of a bicycle. In the inner edge of the web, as shown,
the notches bb are formed, preferably between inwardly projecting lugs b¹ b¹.

page_text: The spider C, which consists of a hub c', and as many arms c as there are
notches b, may also be made of sheet metal; and the hub c¹ may be drawn out into
the form shown. The ends of these arms are offset a distance substantially equal
to the thickness of the web. These offset ends lie against the sides of the web,
while the arms just outside of said offsets, enter the notches b; and screws D, or
other suitable means, fasten together the web and offset ends of arms b.
The two parts of the rim, as shown, are pressed closely together, and the rim is
made so narrow that there is no tendency of the two plies of the rim to spread
apart. The rim, therefore, retains its shape without the necessity of having the
two plies riveted together or without any stiffening piece between them. It is
difficult when the wheel is finished to detect the fact that the rim is made of two
plies of metal.
As shown, parts of the web are punched out, as at 6, for the purpose of
lightening the wheel.
In the modified construction shown in Figure 3, the inner ply of the rim is offset
a little to one side of the web, wherefore the completed rim projects equally on both
sides of the web.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, as communicated
to me by my foreign correspondent, I declare that what I claim is :-
1. In a sprocket wheel, an outer portion consisting wholly of a single piece of
sheet metal, and comprising a single thick web part and a double thick rim part in
which the teeth are formed, the two thicknesses of rim being in close contact and
united by loops at the outer edges of the finished teeth, combined with a spider
having arms which overlap the sides of the web and are secured thereto, the main
portion of the spider arms and web being brought into line by means of an offset
provided at the overlapping junction, substantially as and for the purpose
specified.
2. In a sprocket wheel, an outer portion consisting wholly of a single piece of
sheet metal, and comprising a single thick web part having notches in its inner
periphery, and a double thick rim part in which the teeth are formed, the two
thicknesses of the rim being in close contact and united by loops at the outer edges
of the finished teeth, combined with a spider, the arms of which enter the notches
in said web and having offset ends which lie against and are secured to the sides of
the web, substantially as and for the purpose specified.
3. A sprocket wheel formed substantially as herein shown and described.
Dated this och J
CHARLES JUNGE.