Improvements in Bicycles, Tricycles, and similar Vehicles.
Year: 1890

page_text: Date of Application, 7th May, 1890
Complete Specification Left, 7th Feb., 1891-Accepted. 7th Mar.. 1891
PROVISIONAL SPECIFICATION.
Improvements in Bicycles, Tricycles, and similar Vehicles.
I, ERNST GUSTAV HOFFMANN, of 5, Clarendon Villas, Beaconsfield Road, New
Southgate, in the County of Middlesex, Engineer, do hereby declare the nature of
this invention to be as follows:-
My invention relates to bicycles, tricycles, and similar vehicles, part of same
heing applicable to what are known as tandem safety bicycles, or to tandem
tricycles, and part to eyeles generally.
The
I will describe my invention in connection with a tandem safety bicycle. In
tandem bicycles and tricycles as at present constructed it is necessary to employ
two driving chains with their accompanying parts, one being for each rider.
According to my invention I propose to use one chain only, and impart motion to
the sprocket wheel by crank rods to which are attached on either side of the
machine pivoted levers having at each end pedals which are within reach of each
rider so that both will operate the same sprocket wheel and chain.
sprocket wheel for lightness and cheapness I prefer to make of stamped up steel so
that the teeth of same will be thin and so present small friction surfaces to the
chain, in which at the point where they act I place steel rings or rollers of large
diameter. The steering is effected by the back rider by means of a rod or rods
attached to arms on the steering shaft to which is connected the handle bar for the
back rider and which rod or rods pass to the fork or head of the front wheel. To
enable the front rider however to steer when desirable I affix the fork of the front
wheel to a tubular shaft which passes up a casing or head piece. Inside this
tubular shaft slides the rod of the handle bar which may be either loose or fixed
and yet have no effect on the steering, although it may be readily connected to the
tubular shaft by a set screw so as to enable the front rider to steer with it when
desired. Under ordinary conditions when the back rider is steering the front
handles may be rigidly fixed by the set screw before referred to which is taken
from the boss on the tubular shaft through which it is screwed to the rod and is
screwed through another boss on to the handle rod, this boss being held around the
rod by two short arms attached to the outer easing or head which forms part of
the frame.
Another somewhat similar arrangement for enabling the front handle bar to be
used for steering or not as desired consists in removably attaching it to a shaft
attached to the fork, which shaft is surrounded by a head or casing forming part of
the frame. In this condition it steers the front wheel. To render it non-steering
it is removed from the head of the shaft and placed on a short shaft capable of
sliding in bearings attached to the head or casing, in which position it has no
control over the front wheel.
The back rider is seated almost directly over the back wheel and that portion of
the frame which carries the back seat is adapted to be readily removed, as are also
the steering devices for the back rider so that the machine may be readily
converted into a single machine. The brake is applied to the back wheel,
the connection being by rods which pass to pedals pivoted to the same bar as the
pedal levers. This brake pedal is in a convenient position for being applied by
either the back or front rider.
I prefer to mount the frame on small spring boxes applied to the bearings of ch
wheel, which arrangement, as will be evident. is adapted to other than tandem
bicycles. The arrangement employed consists of a spiral spring which the weight
of the rider compresses, and a smaller spiral spring beneath same which serves to
cushion and receive shocks when travelling, the journals of the wheels being so

page_text: carried that a shock in one direction is received by one spring, and a shock in the
other by the second.
The wheels for the tandem machine above described or for other forms of cycles
I prefer to form as follows :
I thread through a hole in the edge of the hub and through the crown of the
rim a wire which is to form the spoke, bring the two ends together inside the rim,
twist them together as tightly as possible and lay the twisted end in the rim where
it is afterwards covered by the tyre. Each spoke is formed in this way and so
consists of two wires. To tighten up the wheel the two spokes are twisted together
and when tight enough a wire is threaded between same which prevents them
untwisting. This wire is run through each twisted spoke about half way between
the rim and the hub until each spoke has been s prevented from untwisting when
the two ends of the wire are coupled or secured together.
Datal this 7th day at A 180M
PHILIP M. JUSTICE,
55 & 56, Chenery Lane, London, Applicant's Agent."
COMPLETE SPROTEICA,PIN.
Improvements in Bicycles, Tricycles, and similar Vehicles.
I ERNST GUSTAV HOFFMANN of 5, Clarendon Villas Beaconsfield Road New
Southgat in th County of Middlesex Engineer, do hereby declare the nature of
this invention and in what manner the same is to be performed, to be particularly
described and scertained in and by the following statement:-
My invention relates to bicycles tricycles and similar vehicles part of same being
applicable to what are known as tandem saf ty bicycles or to tandem tricycles and
part to eyeles generally,
To early plain the nature of my invention 1 will describe it in connection
with the company ing drawings in which
Figure 1 is an elevation of a tandem bicycle with my improvements applied
thereto.
Figure 11 an enlarged view in section of the spring bearings for the wheels.
Figure 2. is a plan of same.
Figure 3. is an elevation of a "Safety" bieyele with part of any improvements
applied thereto.
Figure 4. is elevation of the driving sprocket wheel.
Figure 5. is an edge view of same in section.
n
Figure 5 is a similar view of the rear sprocket wheel.
Figure 6. is a side elevation of the drawing chain.
Figure 7. is a plan and
Figures 8. al 9. are sections taken respectively on the lines - and y—y of
Figure 7.
In tandem bicycles and tricycles as at present constructed it is necessary to
employ two driving chains with their accompanying parts one being for each ridder.
1 employ one chain a. only and impart motion to the sprocket wheel b. by crank
rods, connected to the cranks d. d of same at one end and at the other end to
levers e. c. pivoted to the framework at and having pedals at either end as shown,
said pedals being within easy reach of the front and back riders so that both will
operate the same sprocket wheel and driving chain. The sprocket wheel b. and the
sinaller one on the rear wheel for lightness and cheapness I make by stamping
from a steel disc in order that the teeth of same may be thin and so present small
friction surfaces to the chain.
The sprocket wheel b. is shewn on an enlarged seale in Figures 4. und 5. and as
will be seen it consists of a thin annular disc b. to which two arms g. g. springing
from a boss 4. are attached at their outer ends by bolts or rivets passing through
the rim of said disc. The third arm springing from this boss h. consists of the

page_text: crank which is similarly attached to the disc by a bolt or rivet. This boss h. is
keyed to the driving shaft which passes through suitable bearings in the framework
and carries at the other end the second crank d. The sprocket wheel for the
rear wheel is shewn in Figure 5". In this it will be seen that the hub has a polygonal
projection on same upon which the wheel (which has a similar opening) is slipped
and held against the shoulder by the nut. The driving chain for use with these
sprocket wheels I prefer to make with steel rings or rollers. Figures 6. and 7. of
large diameter but of little thickness said rings 7. being held between links j. k. in
the usual manner. The links j. however which are the inside ones are stamped up
with a bend or curve 7. in same as shown in Figure 8. to stiffen them and to allow
the teeth of the sprocket wheel to enter easily while the outside links k. have an
indented part (Figure 9.) which stiffens same and at the same time reduces the space
between the two so that the teeth of the sprocket wheel are kept centrally in place
when working against the rings i. Each link has an enlarged disc shaped head m.
nt either end.
The steering is effected by the back rider by means of a rod . attached to a
crank arm secured to the bottom of the steering shaft to which is attached the
usual handle bar and which rod n. passes to the fork of the front wheel. The
steering shaft is carried in the usual tubular casing forming part of the framework
in the ordinary manner.
To enable the front rider however to steer when desirable, the front
handle bar is provided with a short portion which is dropped into a
tubular shaft o. carried by the usual tubular head or casing said shaft n.
having the customary ball bearings and a threaded split end to which a
tapered or conical collar or nut is screwed which affixes the handle rod a to same
by compressing the split end on the portion n. As shewn in Figures 1. and 2. the
handle is in position when it will have no effect on the steering it having been taken
out and dropped into a split bearing or socket of projecting from a head of which
forms part of the frame. The conical nut o' is screwed down on to the split socket o³
so that the handle bar is prevented from being lifted out. In either of these
positions it will be seen it may be adjusted to suit the convenience of different
riders.
The back rider is seated almost directly over the back wheel the rod 1. which
carries the back saddle being adapted to be readily removed as customary as are
also the head or casing 2. with the rear handle bars the steering shaft of same the
crank and the rod . so that the machine may be readily converted into a single
It is obvious also that the crank rod c. may be attached to the lever e. at the
forward end instead of at back as shewn and the lever be made in halves capable of
working together so that the back part may be detached when the machine is to be
used as a single one.
one.
The
The brake is of the band kind and operates on a drum on the back wheel in the
usual way the means for applying same consisting of a rod p. attached to an arm
which is connected at either side of the machine to hell cranks p' said cranks being
pivoted at the points f. to the same bar which carries the pedal levers.
cranks carry rods which serve as foot rests for the back rider and also
enable him to apply the brake. These rests are kept in their back position and the
brake is kept off by a spring ³.
A rod p passes from the cranked arm (to which the rod p. is attached) to the
forward part of the machine where it is attached to a crank pivoted to the framing
said crank carrying rods which are operated by the feet of the front rider.
The framework of the machine is mounted on small spring boxes applied to the
bearings of cach wheel. The boxes for the back wheel are formed of stampings or
castings q. attached to the frame which are capable of rising and falling on a rod r.
carrying a spiral spring which is compressed by the weight of the rider. Said
boxes q. have extensions q' on same which bear and slide upon the forked end of the
rod r. the object of this arrangement being to relieve said rod r. from the pull of the
chain or brake.

page_text: Figure 1 shows on an enlarged scale the construction of the spring boxes for the
front wheel which are similar to those for the back except for the extensions q
the spring in this being shown as partly compressed. It will be seen that the rod r.
is of different diameters and carries a fixed collar between which and the upper
projection of the box y, the spring is compressed. As a means of taking up the
wear I provide split conical bushings which are serewed into the projections of
the boxes y. and which may be tightened up as desired. A smaller spiral spring
may be applied to the rod r. above the first one if desired to cushion and receive
shocks when travelling. The rods r. terminate in forks which may be readily
released from the wheel spindle so that the wheel may be dropped out when desired.
In Figure 3. shew a single machine having these spring boxes, the said machine
also being provided with my improved sprocket wheel operated from a crank d.
erank rod e. and pedal lever e
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 :-
1. In tandem bicycles or tricy les double ended pedal levers centrally pivoted
operating a sprocket wheel through cranks and crank rods substantially as described.
2. In cycles the sprocket wheels formed from thin steel dises in combination with
the chain all constructed substantially as described and illustrated.
3. In eyele spring boxes for supporting the frame constructed substantially as
described and illustrated.
4. In tandem bicycles or tricycle- a tubular steering shaft in the front head and a
bearing or socket carried by said head either being adapted to receive a short shaft
of the handle bar substantially as described.
Dated the 7th day of February 1891.
PHILIP M. JUSTICE,
55 & 58, Chancery Lane, London, Applicant's Agent.