Improved Construction of Fork for Bicycle Frames and like Tubular Structures..
Year: 1898

page_text: Date of Application, 19th Nov., 1898--Accepted, 11th Mar., 1899
COMPLETE SPECIFICATION.
Improved Construction of Fork for Bicycle Frames and like Tubular
Structures..
I, WILLIAM HENRY FAUBER, of 806, Marquette Buildings, Chicago, Illinois,
U.S.A., Manufacturer, 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:—―
This invention relates to an improved construction in forks for bicycle frames
and like tubular structures. The invention is more especially applicable to the
construction of forks for bicycles of that kind which are joined to the hanger or
other part of the bicycle frame by a single frame member, such as the rear fork
which is attached to the seat-post fitting by a single tube or member and forked at
its rear lower ends to form the rear stay arms.
A fork embodying my invention consists generally of two tubes which are
arranged side by side and are long enough to form both the fork sides or arms
and a portion of the shank or body of the fork; each tube forming one fork arm
and one-half or a portion of one-half of the shank, and a tube or thimble which
fits at one end over the shank portions of the tubes and is permanently attached
thereto, and is adapted to engage at its other end a thimble on the crank hanger,
seat post fitting or other part of the bicycle, and forms in connection with the
adjacent ends of said fork tubes the shank of the fork. The said fork tubes are
provided between their ends with double hends by which the parts forming the
shank are offset from the parts forming the arms, and the said off-set parts are
secured to each other side by side, so that they together form a single tubular shank
or double structure. Over said offset portions of said tubes is fitted the sleeve or
tubular sections which form in connection with said offset portions of the tubes the
shank of the fork, said sleeve or tubular section being permanently secured to the
fork members by brazing or otherwise, and having at its end adjacent to the fork
arms parts which are bent over and embrace the joint between the parts which
form the arms. -
The invention consists in the matters hereinafter set forth and more particularly
pointed out in the appended claims.
In the drawings,
Figure 1 is a view partly in elevation and partly in section of a fork constructed
in accordance with my invention.
Figure 2 is a side clevation of one of the offset tubes from which a fork em-
bodying my invention is made.
Figure 3 is a plan view of the two fork members, after they have been bent to
form the offset and ready to be inserted into the shank sleeve.
Figures 4 and 5 are two views of the shank sleerc
Figure 6 is a cross-section taken on line 6-6 of Figure 2.
Figure 7 is a cross-section taken on line 7-7 of Figure 3.
Figure 8 is a fragmentary elevation of the parts of the junction of the shank
and fork members.

page_text: Figure 9 is an end view of the shank sleeve.
As shown in the drawings, A-A indicate tubes forming fork arms or sides,
A-A¹ offset end portions of said tubes which when placed together constitute
a portion of the fork shank, and B a tubular section or shank sleeve which embraces
the offset parts A to form the completed fork shank, and which is adapted to
have engagement at its outer end with the part to which the fork is to be con-
nected. The tubes forming the fork sides and the offset or shank portions are
provided between their ends with double or reverse bends as shown at a, of which
those adjacent to the offset parts are abrupt or practically right-angled bends,
while the others which form the shoulders of the fork are rounded as shown at a.
The offset parts AA are provided each with a flat, inner face ', so that when
the offset parts are placed together they may be inserted within the tube or
sleeve B; said offset parts being made of such length as to extend some distance
into the shank sleeve so as to form a strong and rigid connection hetween the
parts. In order to more firmly join the shank sleeve B to the fork tubes and the
latter to each other, said sleeve is provided at its end adjacent to the fork tubes with
two extensions b, formed by means of opposite notches b¹ cut in the end of the
shank sleeve. The said notches are adapted to fit around and receive the parts of
the fork arms adjacent to the offset portions A¹ when the latter are inserted in the
shank sleeve; while the extensions are adapted to be folded at their ends over the
sides and inner surface of the fork arms so as to cover the meeting edges of said
arms. The offset parts are held by brazing within the fork shank, and when the
projections 6.are bent over the adjacent parts of the fork arms they are brazed or
otherwise permanently secured in place. Said extensions 6 will be made of such
length that when folded together they will meet midway between the sides of the
fork so as to form a flush joint or connection, as clearly seen in Figure 7.
In giving shape to the end of the sleeve B, I prefer to employ a cutting tool, the
radius of which corresponds with that of the curved portions of the fork arms and
having cutting edges shaped to conform to the cross-sectional shape of the outer
surfaces of the fork arms, so that the notches formed by the cutter, as seen in
Figures 5 and 9, will conform exactly to the exterior shape of the fork arms,
while at the same time sharp or feathered edges will be formed at either side of
the extensions 6, as clearly seen in Figure 9. When the sleeve thus made is
placed over the shank portions of the fork arms the portions of said shank between
the projections 6 will fit accurately and closely around the outer surface of the
fork arms adjacent to the bends therein, while the sharp or feathered edges of the
projections 6 will meet the side faces of the said fork arms and leave no abrupt
Aurface or shoulders at the sides of said projection. Moreover, when the extremities
of the overlapping portions or extensions bare bent into their final positions against
the inner surfaces of the fork-arms, as shown in Figures 7 and 8, the sharp or
feathered edges thereof will come in contact with such inner surfaces so that the
said extensions will present smooth and rounded surfaces without any shoulders at
their side edges, and having convexly rounded outer faces corresponding with the
original curvature of the tube forming the shank, as clearly seen in Figure 8.
A principal advantage arising from the novel construction herein described, is 4
that the parts when assembled are brought and held firmly in proper relative
position by the construction and formation of the parts, it being obvious that when
the shank portions of the fork arms are inserted in the sleeve B, and the exten-
sions & are bent inwardly over or around the said fork arms, the parts will be
rigidly and strongly held exactly in their proper positions even before the brazing 5
is accomplished, and no special means, such as riveting or wiring is required for
this purpose.
The employment of the extensions b arranged as described, is of very great
importance and secures important advantages, for the reason that said extensions
when secured by brazing to the fork members at both sides of the line of juncture 5
between them, form stays which serve to resist strains tending to spread apart the

page_text: fork arms, as well as to greatly stiffen and strengthen the structure as a whole.
Moreover, it is found that in the act of bending the fork arms to form the offset
portions the metal is made thinner and therefore somewhat weakened, especially
at the abrupt bends where the flattened portions of the shanks join the curved
inner surface of the fork arms, and it will he apparent that the extensions b, when
brazed to the surfaces beneath them, constitute reinforcements of the metal of the
fork arms at these points; said extensions, in fact, overlapping the adjacent parts
of the fork arms and extending over the same to points outside of the angles or
bends referred to, so that said extensions serve to strengthen and stiffen the fork
arms for some distance outwardly on either side of the bends referred to. The
employment of said extensions therefore gives to a fork crown made in two pieces
a great degree of strength and stiffness at the point at which the two parts forming
the fork crown are joined to each other.
A fork constructed as above described has the advantage of being easily and
cheaply made, while at the same time it possesses great strength by reason of the
fact that the two pieces which form the shank or body portion and the fork sides
are continuous or made in one piece and without joints. The making of the shanks
from the joined end portions of the tubes flattened at their meeting faces in the
manner described, has the advantage of making the shank portion exceedingly
strong and rigid, the same being stronger than a single tube of the same size, by
reason of the double, transverse wall formed by the flattened sides of the two tubes.
A further and important advantage gained by the use of the shank sleeve B
provided with the forwardly extending projections b, is that the joint between the
meeting edges of the tubes at the shank or offset portions is covered by said pro-
jections and the appearance of the fork as a whole thereby greatly improved. In
the practical manufacture of a fork of this general character from sheet metal it is
not usually practicable or desirable to make sharp or angular bends where the flat
parts join the convex or rounded part of the fork shanks, so that a groove or
depression is formed along the meeting surfaces of the two tubes which requires
the use of solder or filling material to give a smooth or continuous surface at the
sides of the joined shank portions. Moreover, the joint at the inner side of the
fork cannot be so made as to provide a continuous curved surface from one fork
to the other, without the use of filling material in the groove or depression referred
to. In the present construction however, this part of the fork is completely
covered by the extensions 6 of the shank sleeve so that the grooves referred to are
entirely concealed and a desirable smooth and finished appearance given thereto.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare the what I
consider novel and desire to claim is;
-
1. A tubular fork consisting of two tubes which are bent to form offset parts,
and a sleeve surrounding said offset parts and having overlapping connection at
its inner end with the parts of the tubes at the junction of the fork arms.
2. A tubular fork consisting of two tubes which are bent to form offset parts,
and a sleeve surrounding said offset parts and provided at its inner end with an
extension which is folded over the meeting portions of the tubes at the junction of
the fork arms.
3. A tubular fork consisting of two tubes which are bent to form offset parts and
a sleeve surrounding said offset parts, and provided at its inner end on opposite
sides thereof with extensions which are folded over said tubes to cover the meeting
portions of the tubes at the junction of the fork arms.
4. A tubular fork consisting of two tubes which are bent to form offset parts, and
a sleeve surrounding said offset parts and provided at its inner end on opposite
sides thereof with extensions which are folded over the parts of the tubes at the
junction of the fork arms and meet end to end between the side faces of said
fork arms,

page_text: 5. A tubular fork consisting of two tubes which are bent to form offset
parts, and a sleeve surrounding said offset parts and provided at its inner end on
opposite sides thereof with notches curved to fit the curved outer surfaces, of the
fork arms and provided between said notches with extensions adapted to be folded
over the inner surfaces of said fork arms at the junction of the Intter.
6. A tubular fork consisting of two tubes which are bent to form offset parts,
and a sleeve surrounding said offset parts and provided at its inner end with notches
curved to fit the curved outer surfaces of the fork arms, and having between said
notches extensions, the inner faces of which are made flat to form feather edges at
the sides of the extensions, said extension being bent over the inner surfaces of
the fork arms with their flat faces in contact with said arms.
Dated this 18th day of November 1898.
H. D. FITZPATRICK,
100, Wellington Street, Glasgow, Agent.