An Improved Frame for Rear-driving Safety Bicycles and other Cycles.
Year: 1889

page_text: Date of Application, 12th Oct., 1889
Complete Specification Left, 17th Dec., 1889-Accepted. 18th Jan., 1890
PROVISIONAL SPECIFICATION.
An Improved Frame for Rear-driving Safety Bicycles and other
Cycles.
I, JOHN BOYD DUNLOP 50 Gloucester Street, Belfast Veterinary Surgeon do hereby
declare the nature of this invention to be as follows :—
This Invention has for its object to produce a spring frame for safety bicycles in which
flexible metallic or other rods are employed to reduce vibration and to maintain the
position of the seat from the driving axle always constant. The improved frame
according to my Invention consists of two or more horizontal parallel bars or rods of
spring steel or other material capable of yielding to the inequalities of the road
surface. Vertical rigid tubes or stays connect these two horizontal spring rods at
front, rear, and centre and maintain same the required distance apart, spring rods
being attached to and connecting these horizontal rods with the axles of the driving
crank and rear wheel. The frame above described is duplicated each side being.
retained a few inches apart so that the rear wheel would be contained inside the
frame. The angled terminations of the duplex spring rods comprising the duplicate
frame aforesaid instead of being solid may be jointed if so desired; suitable rigid
stays are provided one on each side of the rear wheel for connecting the axle of the
latter to the axle of the driving cranks.
Dated this 19th day of Ontoba 1880
JAMES
STEVENSON,
Gray's Inn Chambers, 20, High Holborn, London, W.C.,
Agent for Applicant.
COMPLETE
SPECIFICATION.
An Improved Frame for Rear-driving Safety Bicycles and other
.
Cycles.
I, JOHN BOYD DUNLOP of 50 Gloucester Street, Belfast, Ireland Veterinary
Surgeon 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 the construction of an improved spring frame for safety
bicycles and other cycles wherein flexible flat bars of spring steel or other similar material
capable of yielding to the inequalities of the road surface are employed to reduce
vibration, each flexible bar whilst permitting of an easy vertical motion acts as a stay
or support to the frame and in such a manner that the position of the seat relatively
to the driving or crank axle is maintained always constant.
In order that my invention may be the better understood I have appended the
accompanying drawing illustrating my improvements employed in the construction
of a rear driving safety bicycle.
Referring to the drawing it will be seen that in carrying out my invention I employ
two horizontal, parallel, flexible, flat metallic bars S, S, preferably of spring steel,
placed one above the other. The said horizontal, flexible, flat bars are bifurcated as
shown, such bifurcation permitting of the rear forked terminations being arranged
one on each side of the rear wheel; or, if preferred, I may duplicate, said bars, in
which case suitable crosspieces would be employed to retain same the requisite
distance apart. The front ends of said horizontal bars are bolted, rivetted or otherwise
secured to brackets or lugs formed on the neck pin E. The rear ends of said hori-
zontal flat bars or springs S, S are bolted or rivetted to the vertical, flexible, metallic
fork or support S', the latter having its lower ends bolted or otherwise secured to

page_text: lugs or projections formed on the rear slotted ends of the horizontal rigid fork or
stays B, which connect and maintain the axle of the rear wheel and the driving or
crank axle the requisite distance apart. The vertical support or fork S2 may be
formed separately in one piece as shown, or the same may be formed by continuations
or extensions of the upper horizontal bifurcated or divided duplicate bar aforesaid.
The vertical tube C, within which the seat pillar is adjustably carried, is securely
bolted in position.
The flexible vertical bar S111, forming a continuation of the tube C, is bolted to the
latter and to lugs or brackets on the enclosing bearing case of the driving or
crank axle.
The front fork F, which is of the ordinary construction, is connected to the handle
bar socket or steering post H by the two horizontal flat spring bars S11, S11 as shown,
or, if desired, said flat bars S₁, S" may be duplicated or bifurcated and placed lower
down on each side of the wheel, in a manner somewhat similar to that described and
shown with reference to the rear portion of the frame, in which case a vertical
flexible support would be employed such as that shown for the rear wheel at S in
lieu of the ordinary rigid fork F.
The frame of the cycle constructed in accordance with my invention, as above
described, which in appearance assumes the form of a number of parallelograms, is
exceptionally light and strong and possesses excellent antivibratory qualities.
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 that what I
claim is :
1st. In the construction of frames for safety bicycles and other cycles the employ-
ment of flexible flat bars preferably of spring steel for reducing vibration substantially
as set forth.
2nd. In the construction of frames for safety bicycles and other cycles the combina-
tion of the bifurcated or duplicated horizontal flexible metallic flat bars S, S, vertical
flexible metallic supports S, Su and horizontal flexible metallic flat bars S, Su for
connecting the handle bar socket or steering post H with the front fork substantially
as herein described and shown and for the purposes specified.
3rd. The improved frame for safety bicycles and other cycles substantially as herein
described and shown and for the purposes specified.
Dated this 17th day of December 1889.