Improvements in and connected with Elastic Tyres.
Year: 1897

page_text: Date of Application, 2nd Mar., 1897-Accepted, 28th Aug., 1897
i
COMPLETE SPECIFICATION.
Improvements in and connected with Elastic Tyres.
I, CHARLES EMERSON BULKLEY, of Summit in the County of Union and State of
New Jersey, United States of America, Manufacturer, do hereby declare the nature
of this invention and in what manner the same is to be performed, to be par-
ticularly described and ascertained in and by the following statement :—
The invention relates more particularly to wheels for bicycles and like vehicles
in which strength, lightness and resiliency are the most necessary characteristics.
Pneumatic tires secured to light and strong rims are perhaps the nearest approach
to perfection previously attained but the liability to puncture is great and unless
means for repairing are at hand in case of such accident, the wheel is useless. A
wheel embodying the good points of the air cushion without its attendant disad-
vantages is much to be desired: the present invention is intended to supply such,
and it is believed successfully attains that object.
It consists of an annulus or hollow ring of steel or other strong and resilient
material, forming the wheel rim, receiving the spokes on the inner face and having
a continuous open channel or slot cut through to the interior on the periphery along
the line of the tread.
When a load is applied, the rim tends to flatten at the point in contact with the
ground, into an approximately elliptical cross-section by increasing the width, this
tendency is resisted by the stiffness of the curved springs forming the sides of the
rim; the resistance increases in proportion to the weight of the load for the reason
that the effective length of the springs is reduced by the amount of the increased
area brought in contact with the ground.
In the most approved form of the invention the cross-section of the rim is crescent-
shaped, being thicker along the line at the junction with the spokes and gradually
thinning in both directions toward the slot; the edges or lips so produced engage
and hold an annular shoe or tread of soft vulcanized rubber grooved on the opposite
faces to receive them. The portion of the shoe exterior to the rim is curved away
from the latter on the adjacent face so that the flattening of the rim and the com-
pression of the shoe combine to close the joint between them and thus lessen the
effective length of the springs.
A narrow flange of rubber forming another portion of the shoe extends vertically
across the interior of the rim and aids in resisting the tendency to flatten.
The accompanying drawings form a part of this specification. Figure 1 is a
side view of a complete wheel constructed in accordance with my invention.
Figure 2 is a cross-section through the rim and shoe on a larger scale. Figure 3
is a corresponding view showing the form assumed by the same parts when sustain-
ing a load. Figure 4 is an edge view of a portion of the rim alone. Figure 5.is
a face view of a portion of the shoe. Figures 6, 7 and 8 are cross-sectional views
showing several modified forms of the rim alone.
Similar letters of reference indicate like parts in all the figures.
Referring to Figures 1, 2, 3, 4 and 5 which show the invention in its most com-
plete form, A is the wheel-rim of steel or other material having a high degree of

page_text: elasticity. It is produced in the form of a strip thickened along the centre line
and gradually thinned toward each edge, the strip is rolled into tubular form by
treatment in suitable dies or otherwise, bringing the edges nearly in contact with
each other, and the ends are joined by brazing to form a hollow annulus the section
of which shows as a crescent, thicker at A¹ and terminating in the thin lips A2, A².
A central rib A3 on the inner surface of the portion A¹ extends completely around
and affords sufficient metal in which to set the spokes I which may be of any of
the well known forms and secured in any ordinary or approved manner; I have in
these figures shown them as screwed into holes drilled and tapped at the proper
intervals in the rim. The adjacent edges of the lips are smoothly finished and
rounded to avoid cutting, and match to annular grooves b, b produced on each face
of a ring of soft vulcanized rubber B. This shoe is inserted by forcibly parting
the lips A and crowding it through the peripheral slot a between them; it affords
meaus for insuring a reliable hold on the ground and comprises the tread B¹ con-
nected by the narrow neck B33 between the grooves b, b, and the shoulder B' to
the supporting flange B3 extending vertically across the interior of the rim and
finding a bearing against the face of the rib A³, the flange is thickened just above
the neck to match to and increase its effective base on the inner face of the lips A³
and tapers slightly therefrom.
The portion B forming the tread is elliptical in cross-section as shown, the upper
surface curving away from the adjacent faces of the lips so as to lie against a
narrow line only on each, close to the edge when the wheel is not sustaining a
load. When the load is applied, as by a person mounting the wheel, the tread B¹
flattens somewhat at the point in contact with the ground, as does also the rim A,
the several parts assuming positions approximating those shown in Figure 3,
increasing the area of the joint betwen the lips A2 and the shoe thereby reducing
the length of the free arms of the crescent on each side, forcing the flexion to take
place at points further from the lips and where the metal is thicker and corre-
spondingly stiffer. The flange B3 is also compressed, thereby extending the
bearing surface forming its base and assisting the tread B¹ in holding the thin
edges A2 against springing and also by acting strut-wise between the lips and the
rib A³ resists the tendency of the rim to shorten its diameter on that line.
The elasticity or resiliency may be described as obtaining in three portions of
the rim and shoe:-
First and principally in the springs formed by the curved sides of the rim,
secondly in the compression of the tread of the shoe, and third in the compression
of the flange B³. In applying a light load the first effect is to deflect inward the
sides of the rim nearest the lips A2, to slightly compress the tread B¹ and also the
flange B if the latter fills the space very exactly; a further accession of weight
still further flattens the rim, compresses the tread of the shoe and closes the
surfaces of the grooves upon the lips; the flange asserts itself by oppressing its
mass to the crushing strain, and any additional weight finds all parts working
together to resist further depression.
By dispensing with the usual rim and tire and substituting the form here shown,
a considerable saving in weight may be effected, but the main advantage in this
invention is the freedom from the evil of puncture requiring either that the rider
be equipped with a repair kit and sufficient mechanical skill to use it or rely on
finding a repair shop at which the leak may be stopped. The construction here
shown will allow the rider to continue if necessary even though the rubber shoe
be cut entirely through and rendered useless, by riding with the curved sides of
the rim in direct contact with the ground, the resiliency afforded by the spring
of the rim being sufficient to enable him to ride without serious discomfort or
danger of damage to the wheel.
It is believed that the peculiar effect of the pneumatic tire, namely the property
of momentarily imbedding within itself any small obstruction in its path instead
of requiring the entire load to be lifted in surmounting it, will be found to a great
degree in this mode of construction.

page_text: Modifications may be made in the forms and proportions without departing from
the principle of the invention or sacrificing its advantages.
Figure 6 shows a shape similar to that described but made from a strip of
uniform thickness throughout; the strengthening rib A³ is here shown as a
separate reinforcing piece secured in position by riveting or otherwise.
In the modification shown in Figure 7 the rim is built up of several slotted tubes
one within the other, each having a narrower slot than the one it encloses; this
form will have an action somewhat analogous to a "leaf" spring.
Figure 8 shows a triangular form of cross-section.
I may if it be deemed expedient soften the yielding action of the springs by
producing transverse slots or openings in the sides, or the ends of such slots
may be cut away to form teeth or fingers of greater or less length engaging the
shoe between their tips or ends.
The material has been described as steel and I believe such to be generally
preferable but other metals may be used and also other materials including hard
rubber, gutta-percha or celluloid in its various forms.
The best proportions in regard to the thickness of the rim, width of tread of the
shoe, distance between the lips, and the like, have not been fully determined and
will depend in great measure on the material used. The drawings show these
details as designed for steel.
Although I have described the invention as applied to a wheel rim it will be
understood that it may be made to serve as a tire and be attached to any of the
usual forms of rims to which it is adaptable.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is:-
1. In a vehicle wheel, a tubular rim of resilient material, having a peripheral
slot on the line of the tread, the free edges and side walls of the tube serving as.
springs to support the load, in combination with an annular shoe serving as a
bearing surface for the wheel and a supporting flange bearing against the inner
face of the rim diametrically opposite said slot, substantially as herein specified.
2. In a vehicle wheel, a tubular rim of resilient material, having a peripheral
slot on the line of the tread, the free edges and side walls of the tube serving as
springs to support the load, in combination with an annular shoe serving as a
hearing surface for the wheel and having a supporting flange B3 bearing against
the inner face of the rim diametrically opposite said slot, substantially as herein
specified.
3. In a vehicle wheel, a tubular rim of resilient material having a peripheral
slot on the line of the tread, the free edges and side walls of the tube serving as
springs to support the load, in combination with an annular shoe matching said
slot and held therein to serve as a bearing surface for the wheel and having a
supporting flange extending across the rim and bearing against the inner face
thereof diametrically opposite said slot, all substantially as herein specified.
4. In a vehicle wheel, a tubular rim of resilient material, reinforced interiorly
along the line of attachment of the spokes to receive the latter, and having a
peripheral slot on the line of the tread, in combination with an annular shoe
matching to and held in said slot to serve as a bearing surface for the wheel
and having a portion extending across the rim and bearing on said reinforce, all
substantially as herein specified.
5. In a vehicle wheel, a tubular rim of resilient material, receiving the spokes
in a thickened portion and gradually thinned therefrom toward a peripheral slot
formed on the line of the tread, in combination with an annular shoe matching
to and held in said slot to serve as a bearing surface for the wheel, substantially
as herein specified.
G. In a vehicle wheel, a tubular rim of resilient material, receiving the spokes
in a thickened portion and gradually thinned therefrom toward a peripheral slot

page_text: formed on the line of the tread, in combination with an annular shoe matching
to and held in said slot to serve as a bearing surface for the wheel and having a
portion extending across the rim and bearing against said thickened portion,
substantially as herein specified.
7. In a vehicle wheel, the tubular rim crescent-shaped in cross-section, the
thickened portion A¹ receiving the spokes and the thin lips A² having their
adjacent edges rounded and the peripheral slot a between them, in combination
with the annular shoe having the grooves bengaged by said lips, the neck being
thickened to form the bearing surface B on the interior of the rim and the tread B¹
on the exterior thereof, and the flange B³ within the rim, all substantially as
herein specified.
8. In a vehicle wheel, the tubular rim crescent-shaped in cross-section, the
thickened portion A¹ receiving the spokes, the additional strengthening rib A³
thereon, and the thin lips A2 having the peripheral slot a between them, in com-
bination with an annular shoe having grooves b engaged by said lips, the bearing
surface B on the interior face of the rim, the tread B₁ on the exterior thereof and
the flange 133 extending vertically across the interior of the rim and abutting
against said rib, all substantially as herein specified.
Dated th
1
1000
CRUIKSHANK & FAIRWEATHER,
Chartered Patent Agents, 62 St. Vincent Street, Glasgow,
Agents for the Applicant.
CRUIKSHANK & FAIRWEATHER,
Chartered Patent Agents, 62 St. Vincent Street, Glasgow,
Agents for the Applicant.