Improvements in Forks and Ball-bearings for Cycles.
Year: 1899

page_text: PROVISIONAL SPECIFICATION.
Improvements in Forks and Ball-bearings for Cycles.
JOHN BOYD DUNLOP, Ailesbury Road, Dublin, Gentleman, JOHN BOYD DUNLOP,
Junior, Ailesbury Road, Dublin, Gentleman, do hereby declare the nature of this
invention to be as follows:
This invention relates to improvements in spring forks and ball-bearings for
cycles, and consists of cross arnis secured to the prongs of an ordinary cycle front
fork, links rigidly secured to each end of the front wheel axle and pivotted to the
cross arms by ball-bearing joints, and spiral springs interposed between the ends
of the cross arms and the links, over the axle.
The objects of this invention is to simplify the securing of the cross arms to the
prongs of the forks, and to make the parts strong, rigid, and light.
The cross arm is bent or curved and is made oval in section, deeper than
broad, or it may be made semi-circular, or Hin section. The lug is forged solid
with the cross arm and is fitted into the end of the fork and brazed. The cross
arm is made stronger at the lug and lighter at each end. The link also is made
oval, semicircular, or H in section, and is made thickest at the end joining the
wheel axle where the greatest strength is required, and tapered to the pivot joint.
The ball-bearing cones on the wheel axle are made solid with the axle, and extend
and fit into tapered holes in the links, for the purpose of giving increased torsional
rigidity to the axle without increasing the diameter of the ball race, the adjust-
ment of the bearing being effected by the cups or discs.
The cross arms and links are arranged side by side where they are pivotted.
The cups of the ball-bearing joint are preferably formed in the links, and the
pivot pin or axle is held in the cross arm. One of the cones is formed solid with
the pivot pin, and the bearing is adjusted by means of the other cone, which has
a conical shoulder fitting into a hole in the cross arm. The pin is secured in the
hole in the cross arm by a conical nut. Alternatively, the pin may be screwed
into the cross arm and locked by the inside cone, which has a conical shoulder
fitting into the hole in cross arm, the bearing being adjusted by an outside cone
screwed on the pivot pin, and locked by a D washer and nut.
Dated this Fourteenth day of January. 1899.
We, JOHN BOYD DUNLOP and JOHN BOYD DUNLOP, Junior, both of Ailesbury
Road, Dublin, Ireland, Gentlemen, do hereby declare the nature of this invention
[Price 8d.1

page_text: 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 improvements in spring forks of the kind described
in Specification No. 23829 for improvements in forks and ball bearings for cycles,
dated 12th November 1898, and has for its object the improvements of the con-
struction of the cross arms, links and wheel bearings of the same. According to
this invention we also construct the wheel axle in such a manner that the wheel
bearings may be adjusted without interfering with the other members of the spring
fork.
In the accompanying drawings which illustrate these improvements as applied
to a spring cycle fork of known construction.
Figure 1 is a perspective view of a spring fork, part being in section.
Figure 2 is a plan of the same, and
Figures 3 and 4 illustrate details of construction.
In the spring fork illustrated in the drawings the end of each blade of an
ordinary fork A is provided with a cross arm B secured to it by means of a lug C.
To one end of the cross arm B is pivotted a link D, the free end of which is rigidly
connected to the axle E of the road wheel, and between the free ends of the cross
arm B and link D is arranged a spring F secured in place by means of lugs and
nuts FF. The link 1 is pivotted to the arm B by means of a ball bearing
joint G, which may be of any well known construction.
The particular formation of the cross arm B with its lug C is shown in detail
in Figure 3; the lug C is made solid with the arm and may be either welded or
brazed on to the same or forged in one piece with the arm. The arm is oval in
cross-section, being thickest at that point where the lug is attached and tapered
down towards each end. The link 1), shown in detail in Figure 4, is also oval in
cross-section, being thickest at the end D which joins the axle E and tapering
down to the end which is pivotted to the arm B. Either of these members may
be made of semi-circular or H-cross-section, the vertical diameter being however
always greater than the horizontal diameter.
The axle E with its cones E¹ (one only being shown in the drawings) are pre-
ferably made integral, the axle being extended at each end direct from the ball-
race and tapered to receive the ends of the links D. Each link is provided with a
conical socket I to receive the end of the axle, and that part of the axle which
projects through the link is screw-threaded and provided with a nut I' which when
in place rigidly connects the two members. A cup H is screwed into each end of
the hub H which forms part of the road wheel and the cup is locked by a nut H³
screwed on to that part of it which projects beyond the hub. It will be seen that
by these means the axle E may be made of considerable diameter throughout its
length without increasing the size of the cones E¹, thus giving it strength to resist
any torsional strain which may be put upon it, and the cups H (one only of which
is shown in the drawings) may be readily adjusted by means of the lock nuts H³,
without interference with the links D or springs F.
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 the combination with lugs C solid
with cross arms B of horizontal or slightly inclined links such as D which are
rigidly secured to the road wheel axle.
2. In a spring fork for a cycle or like vehicle links such as D of greater vertical
than horizontal diameter and tapered down from the end D¹ to the end D³ sub-
stantially as described or illustrated in Figure 4 of the accompanying drawings.
3. In a spring fork for a cycle or like vehicle cross arms such as B having lugs C
solid with them the arms being of greater vertical than horizontal diameter and of

page_text: greatest diameter at that part where the lugs C are attached substantially as
described or illustrated in the accompanying drawings.
4. In a spring fork for a cycle or like vehicle cones E¹ solid with the axle E
the thickness of the axle being extended from the ball-race substantially as
described and illustrated in Figure 2 of the accompanying drawings.
Dated the uay
mer
ecor
JOHN BOYD DUNLOP.
JOHN BOYD DUNLOP, JUNR.
Boult, Wade, & Kilburn,
Agents for the Applicants.
JOHN BOYD DUNLOP.
JOHN BOYD DUNLOP, JUNR.
Boult, Wade, & Kilburn,
Agents for the Applicants.