Improvements in Tandem Bicycles.
Year: 1899

page_text: Date of Application, 16th May, 1899
Complete Specification Left, 16th Feb., 1900-Accepted. 24th Mar 1000
Improvements in Tandem Bicycles.
I, NAPOLEON EDWIN WILLIAM ATKINS, of 23, Gordon Road, New Wanstead,
Essex, Gentleman, do hereby declare the nature of this invention to be as
follows:-
This invention relates to improvements in tandem bicycles and has for object
to reduce the draught, weight and friction.
For this purpose the frame is similar to that of an ordinary safety bicycle
with the addition of an extended length or prolongation of the top tube from the
front saddle pillar, bush and socket, the same running about parallel to the
chain stays and terminating in a second saddle pillar socket to which is fitted
a second saddle pillar and two extra back stays or a single bifurcated tube.
The said stays or tube extend downwards, more or less parallel to the forward
saddle tube, to the axle of the back wheel the additional framing, with the
ordinary rear fork forming a complete triangle with the apex resting in bearings
on the axle of the back wheel and back crank axle, which is one and the same
axle, its ball bearings running in bearing jaws.
The handle for the second rider are fitted to the front saddle pillar as in the
ordinary tandem.
In addition to the ordinary chain wheels there are two auxiliary chain wheels
on the other side of the machine, the front one of which is fixed to the crank
axle, whilst the rear one is fixed to the driving wheel axle and not to its hub.
These wheels may be of the same diameter and are joined by an auxiliary
chain, the axle being fitted with pedal cranks for the second rider and rotating
in additional ball bearings in the same direction as the wheel hub, the hub
having separate ball bearings and the back wheel having four ball bearings
instead of two.
By this arrangement the back wheel is the same distance from the front wheel
as in an ordinary safety, and the wheel running in the same direction as its
shaft lessens the friction, and the riders are carried equally distant on each
side of and above the rear axle.
Dated this 1011 1
1000

page_text: 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 improvements in tandem bicycles and has for object
to reduce the draught, weight and friction.
For this purpose the frame of the machine is similar to that of an ordinary
safety bicycle but with the substitution for the back fork of a triangular frame
pivoted to the rear end of the top tube and terminating in a second saddle pillar
socket.
The angular stays of the said frame are in the form of forks and extend
downwards to the axle of the back wheel, the apex of the triangle resting on
bearings on the said axle, one on each side of the wheel, and the axle being
provided with cranks for the second rider.
The rear fork of the extra frame runs more or less parallel with the forward
saddle tube, and the driving wheel axle runs loosely in ball-bearings carried by
the lower horizontal stays with which the top tube of the said frame is parallel,
the handles for the second rider being fitted to the front saddle pillar as in
an ordinary tandem.
In addition to the ordinary sprocket wheels there are two additional sprocket
wheels on the other side of the machine, the front one of which is fixed to the
front crank axle, whilst the other one is fixed to the driving wheel axle.
These wheels are of the same diameter and are connected by an auxiliary chain,
the rear axle rotating in the same direction as the wheel hub which is provided
with separate ball-bearings to those of the axle.
By this arrangement the rear wheel is the same distance from the front wheel
as in an ordinary safety bicycle, and the wheel running in the same direction
as its shaft reduces the friction. The riders are also carried equally distant on
each side of and above the rear axle.
By means of my invention the machine may also be converted into an ordinary
bicycle by disconnecting the triangular rear frame and substituting in place
thereof an ordinary rear fork.
In the accompanying sheet of drawing Fig. 1 is a side elevation of a tandem
bicycle according to my invention. Fig. 2 is a section of the driving wheel hub
and bearings, and Fig. 3 is a plan of the front crank axle bearing and sprocket
wheels. Fig. 4 is a detached view to a larger scale of the triangular frame
pivoted to the top tube, Fig. 5 is a rear view thereof and Fig. 6 is a plan of the
top tube of same. Fig. 7 is a rear view of the fork substituted for the said frame
when converting the machine into an ordinary bicycle for one rider.
a is the socket of the upper tube supporting the front saddle b.
c is the upper
tube of the triangular frame which is pivoted to the lug on the socket a, and e
is the rear fork brazed at its upper end to the socket at the end of the tube c
and forming with the other fork g the angular sides of the triangular frame.
These forks are brazed to the pieces h at the bottom and to the tube c at the top
so as to form a single frame the pieces h being bolted to the lugs carried by
the bearings of the rear wheel axle j.
g
The socket supports the second saddle k, and are the handles for the
rider thereof carried by the front saddle pillar. m are the lower stays with which
the tube is parallel, the said stays being connected to the axle bearings n,
Fig. 2, by means of the angle-pieces o and studs and nuts p so that the rear
wheel and axle may be readily removed or fixed in position when required.
is the large sprocket wheel and r the small one fixed to the hub s of the driving
wheel, whilst and u are the sprocket wheels on the other side of the machine
of equal diameter and connected by the chain v, the wheel t being mounted on
the shaft running loosely in the ball-bearings of the hub s, and supported at
each end by the bearings n, and the wheel u being mounted on the crank or
front driving shaft w. The forks or stays e and g are formed of greater diameter
at the middle than at the ends to add to their strength and rigidity. When

page_text: converting the machine into an ordinary safety bicycle the triangular frame is
removed by unfastening the bolt connecting it to the lug d, and the lugs i.
The fork Fig. 7 being then bolted in position to the said lugs d and i thus
forming the ordinary rear fork.
For tightening the chain I may use an ordinary eccentric or other adjustment
applied to one of the axles.
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) The improved tandem bicycle comprising a triangular rigid frame pivoted
to the upper tube of an ordinary safety bicycle in substitution for the rear
fork and carrying a second saddle, the said frame being supported by the bearings
of the driving wheel axle, which latter is mounted loosely in the bearings of
the wheel hub and in bearings connected to the lower stays of the machine,
sprocket wheels mounted on the front and rear axles, and on the driving wheel
hub, and driving cranks mounted on each of the said axles, substantially as
described.
(2) In tandem bicycles the combination of a rear triangular frame composed
of an upper tube and two inclined forks formed of tubes of greater diameter
at the centre than at each end, and a driving wheel whose axle is mounted
loosely in its hub so as to revolve therewith and is provided with cranks the
said axle and hub being connected with the front driving axle by sprocket wheels
and chains, substantially as described and for the purposes specified.
Dated this 16th day of February 1900.
J. B. FLEURET,
5, Hatton Garden, Holborn Circus, London, E.C.,
Agents for the Applicants.