Improvements in Forks and Ball-bearings for Cycles.
Year: 1898

page_text: Date of Application, 12th Nov., 1898
Complete Specification Left, 11th Aug., 1899-Accepted, 21st Oct., 1899
PROVISIONAL SPECIFICATION.
Improvements in Forks and Ball-bearings for Cycles.
We, JOHN BOYD DUNLOP, Ailesbury Road, Dublin, Gentleman, and Jon Born
DUNLOP, Junior, Ailesbury Road, Dublin, Gentleman, do hereby declare the
nature of this invention to be as follows:-
This invention is to reduce vibration and to maintain the latteral rigidity of
the front wheels of cycles in a simple and effective manner with a minimum of
friction; and, also to improve the bearings of cycles.
A cross arm is secured to the end of each prong of the front fork. To the lower
and hind end of the cross arm a horizontal or slightly inclined link is pivotted.
The other end of the link is rigidly secured to the end of the axle. The axle
being rigid with the links, is held in a position parallel to the pivotted joints;
the wheel is therefore maintained in a latterally rigid position. In order to give
further latteral rigidity to the wheel, the links may be extended to form a fork
round the wheel.
The cross arm is lapped with a band of steel, and the ends of the band are
inserted into the tubular end of the fork, and the parts brazed together.
A spiral spring is interposed between the forward and upper end of the cross
arm and the forward end of the link, over the axle. The spring is secured to the
cross arm and link by means of bolts or studs, and nuts, the studs being preferably
made solid with the arm and link, or, the lower end of the spring may be held in
position by a bolt with an eye passed on to the axle.
The fork may be projected in front of the axle, and the links pivotted directly
to the ends of the fork; in this case the spiral spring is interposed between
the hind end of the links, over the axle, and a suitable lug or seat on the fork to
which it is secured by means of a stud or bolt, and a nut; or, the fork may be
extended under the axle, and the ends of the fork suspended from the axle by
spiral springs, the horizontal or slightly inclined links being pivotted to the
fork.
In all cases we prefer to arrange the spiral spring directly over or under the
axle with the object of reducing the friction in the pivot joint to a minimum.
We prefer to arrange the arm and link, side by side where they are pivotted.
The pivot pin is screwed into a tapped hole in the arm and is locked by a nut on
the outside, or, by a cone on the inside.
The pivot joint is preferably provided with ball bearings, preferably with two
ball races close together. The ball bearings may be either disc or cone adjusting.
In adjusting by the cone, the cone may be locked in the usual way by means of
a nut.
One of the cones may be formed solid with the arm and the other solid with the
pivot pin; the bearing being adjusted in this case by screwing the pin into the
arm and locking the pin by a nut. In adjusting by the disc the cones are formed
together and solid with the pin and the discs are locked by one cotter, or by
clipping.
The end of the axle is tapered and fits into a tapered hole in the end of the link

page_text: and is rigidly held in position by a locknut, or the end of the axle may be tapered
and oval, or have one or more tapered flats fitting into coresponding holes, or
we may secure the links to the axle by means of the well known cotter-pin, or by
splitting the end of the link and clipping with a bolt; all these methods of
securing the axle to the links being independent of the locking of the wheel
bearing.
In place of hardening the cups or discs in the usual way by placing them in a
box filled with carbon, a number of the cups are placed on a bolt and each cup
filled with carbon and are held together by a washer and nut on the bolt, they are
then placed in a suitable furnace and are so case hardened on the inside only,
leaving the outside tough and strong.
T
1000
4
We, JOHN BOYD DUNLOP, Gentleman, and JoHN BOYD DUNLOP, Junior,
Gentleman; both of Ailesbury Road, Dublin, Ireland, 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 is to provide an improved construction of spring forks and ball
bearings for cycles.
Many devices for absorbing vibration by the introduction of springs or flexible
parts into the frames of cycles. have been tried but owing to complication, excessive
wear and friction of jointed portions or lack of lateral rigidity all have as yet proved
unsatisfactory.
This invention avoids the causes of deficiency mentioned above and has broad
reference to the front or steering forks of bicycles, tricycles and motor vehicles.
In the accompanying drawings which illustrate one form of construction
according to this invention,
Figure 1 is an elevation, and
Figure 2 is a plan of the spring fork device.
'Like letters indicate like parts. throughout the accompanying drawings.
The cross arm B is lapped with a band of steel C and the, ends of the band
are inserted into the tubular end of the fork and the parts brazed together. The
cross arm B is preferably curved or bent in elevation and the prong A attached
to the convex side at a point at or about the centre of its length.
Ahink D is pivotted to the rear and lower end of the cross arm B, the free
end of the link being. rigidly secured to the axle E of the road wheel. The
link D is kept in an approximately horizontal position and the forward and
upper end of the cross arm B is maintained at a proper distance from the free
end of the link D by a spiral spring F which is normally in compression. The
studs F are forged: solid on the ends of the cross arm B and link D and threaded
to receive the ends of the spring F which is secured thereto by nuts F2.
In all cases we prefer to arrange the spiral spring directly over or under the
axle with the object of reducing the friction in the pivot joint to a minimum and
we prefer to have the spiral spring in compression and directly over the axle as
shown as it then acts as a stop when fully compressed.
The link D is pivotted to the cross arm B by a ball-bearing joint shown in
section in Figure 2. The cups G4 of the ball bearing joint are preferably formed

page_text: integral with the links as shown, races. being thus provided for the balls G³. G is
a pivot pin carrying the cone G³. The adjusting cone. G¹ which the pivot pin
. screws into, is solid with or secured to the cross arm in such a manner as to prevent
it turning in relation to the cross arm. This cone may be prevented from turning
by means of a pin passing into the cone and cross arm or by means of a flat on
the cone bearing against a corresponding flat on the cross arm. The bearing is
adjusted by screwing the pin through the cone G¹ and into the cross arm and the
pin is secured in the cross arm by the nut G. The ball bearing joint with its
cups G is preferably formed in the end of the link D as shown but it may bo
formed in the cross arm B and the pivot pins secured in the link D.
The end of the axle E which carries the hub H of the road wheel is tapered
and fits into a conical hole I in the free end of the link D and is rigidly secured
by a nut I. The end of the axle E may be oval and tapered or have one or
more tapered flats fitting into coresponding holes in the link D, or, we may secure
the links to the axle by means of the well known cotter pin, or by splitting the
ends of the link and clipping with a bolt; the link D being thus detachable from
the axle E.
In order that the attachment of the link D to the wheel axle E may not inter-
fere with the adjustment of the wheel bearing the ends of the axle are extended a
sufficient distance outward.
We make the wheel axle somewhat stronger than those ordinarily in use to
increase its torsional rigidity and thereby render the wheel more rigid laterally.
In place of hardening the cups or discs in the usual way by placing them
in a box filled with carbon, a number of the cups or cupped links are placed on a
bolt and filled with carbon, and are held together by a washer and nut screwed on
the bolt, they are then placed in a suitable furnace and are so case-hardened on
the inside only, leaving the outside tough and strong.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we declare that what
we claim is: -
1. In a spring fork for a cycle or like vehicle connecting each blade of the fork
to the axle of the wheel by means of two rigid members such as B and D pivotted
together and triangularly arranged with relation to a third resilient member such
as F and the axle E rigidly secured to the link D substantially as described.
2. In a spring fork for a cycle or like vehicle, horizontal or slightly inclined
links such as D rigidly secured to and pointing back from the wheel axle E and
pivotted to the fork by ball bearing joints.
3. In a spring fork for a cycle or like vehicle horizontal or slightly inclined
links pivotted by ball bearing joints directly or indirectly to each blade of the
fork and rigidly secured to the axle E and detachable therefrom without inter-
ference with the adjustable parts of the wheel bearing substantially as described.
4. In a spring fork for a cycle or like vehicle coiled springs held in place by
studs such as F¹ solid with horizontal or inclined pivotted links which are rigidly
secured to the wheel axle.
5. In a spring fork for a cycle or like vehicle coiled springs held in place
by studs such as F1 solid with horizontal or inclined pivotted links which are
rigidly secured to the wheel axle and studs such as F¹ solid with cross arms
such as B.
6. In a spring fork for a cvele or like vehicle a wheel axle having tapered
ends I to which horizontal or slightly inclined pivotted links such as D are rigidly
secured without interfering with the adjustable parts of the wheel bearing.
7. In a pivotted joint for a spring fork for cycles or like vehicles a cone
such as G secured to either the member B or D-in such a manner as to prevent
its turning when the bearing is being adjusted--in combination with horizontal
or inclined links which are rigidly secured to the wheel axle E.

page_text: 8. The complete spring fork device constructed and arranged substantially as
described and illustrated in the accompanying drawings.
9. Hardening cups or discs for the ball bearings of a cycle or like vehicle on
the inside only substantially as described.
J. B. DUNLOP,
J. B. DUNLOP, JUNR.
Boult & Wade,
Agents for the Applicants.
Dated this 9th day of August 1999.
J. B. DUNLOP,
J. B. DUNLOP, JUNR.
Boult & Wade,
Agents for the Applicants.