New or Improved Automatic Variable Driving Gear for Velocipedes.
Year: 1899

page_text: Date of Application, 1st Mar., 1899-Accepted, 1st Apr., 1899
COMPLETE SPECIFICATION.
New or Improved Automatic Variable Driving Gear for Velocipedes.
1
'
I, AXEL FREDRIK ABRAHAMSON ROXENDORFF, of Tegnergatan 34, Stockholm,
in the Kingdom of Sweden, Engineer, do hereby declare the nature of this inven
tion and in what manner the same is to be performed to be particularly described
and ascertained in and by the following statement:-
.1 For the propulsion of a velocipede a greater or less expenditure of power is
required according to the inclination or condition of the road. The machine,
therefore, is occasionally provided with a variable driving gearing in order that,
when the machine runs easily, the treadle. motion may be worked with great
velocity ratio so as to make the speed quicker, while, when the machine runs
heavily, a reduced velocity ratio may be used. The change of the gearing has
heretofore been effected by hand.
The present invention is based on the principle that when the machine runs
heavily, as for instance in travelling on a bad road or up a grade, a greater pres-
sure is exerted on the treadles by the rider than when the machine runs easily.
The driving arrangement consists of oscillating treadles, drive-chains, and rat-
chet-couplings. As the drive-chain may be arranged in various manners, the
arrangements shown in Figs. 1 and 2 of the accompanying drawings are only to
be regarded as examples of the mode of arranging and locating the self-regula-
ting device referred to.
From the treadle T, Fig. 1 the chain 1 (which is passed over the pulley E,
mounted on the treadle) passes up to a sliding piece G, adapted to be moved along
a guide B formed by one of the lower braces of the frame, said guide being shaped
as an involute of a circle and provided with notches (i) for retaining the sliding
piece in a position corresponding to the pressure on the treadles, as will be more
fully explained below.
When the treadle is depressed, a tension is produced in the chain D, which
tension is the resultant of one force & perpendicular or radial to the guide B,
and one force directed tangentially with reference to the said guide. When
the treadle is in the upper portion of its stroke, and the sliding piece is in its
forward position, this tangential force is equal to zero, since the chain is here
perpendicular to the guide. As the angularity of the chain becomes greater in.
the down stroke, the said force increases in size. The sliding piece G is connected
to the rod k, which is attached to a collar H that can be shifted by the said rod
on the frame tube H. In the interior of or around the tube H a spiral spring f
is located which by bearing against an adjustable abutment or collar g strives
to push the collar H forward together with the sliding piece G, thus counter-
acting the force d'. When the pressure on the treadle is increased, for instance
in travelling up a grade of the road, the force a acting on the treadle is increased
and consequently the force as well which overcomes the resistance of the
spring f. this action taking place in the lower portion of the stroke of the treadle.
The sliding piece is consequently moved rearward, for instance into the position
A, until equilibrium is reached the tension in the chain D being thus increased

page_text: from a to a¹. Thus with increasing resistance an increase of the force exerted
and automatical decrease of the velocity ratio of the gearing takes place. As,
however, on the subsequent raising of the treadle the pressure bearing on it is
reduced to a considerable extent, the sliding piece would travel repeatedly back
and forth on the guide were it not for the introduction of the notches i above
referred to on the guide, said notches. consequently in the rear positions of the
sliding piece preventing the return of the sliding piece by the spring. On the
other hand; when the resistance has become smaller, i.e. when the rider is travel-
ling on a smooth road or down an incline, the pressure in the treadle is relieved
by the rider to such an extent that, the power of the spring will be sufficient to
return the sliding piece to its position for increased velocity ratio of the gearing,
in spite of the presence of the aforesaid notches. The latter, evidently, must be
"so shaped or rounded off that their resistance to the motion of the sliding piece
on the guide will be gauged to suit the power. of the spring and, the degree of
sensitiveness required of the gear.
i
The tube Hmay be cut open at its under side and the spring placed in its
interior, a lug for operating on one end of the spring being in this case made
to enter the tube from the collar H and another one from the abutment-collar g.
By moving the abutment g so as to increase or decrease the tension of the spring
the driving gearing may be adjusted to suit higher or lower stages of power-
development, the abutment g being for this purpose provided with some suitable
arrangement for fixing it in position. Both collars Hand g are made so as to be
easily reached by the rider.
Fig. II shows a modified arrangement where the end of the chain is attached
to the treadle and the pulley is made to slide along the are B and is connected
by means of the rod k with the collar H which can be shifted on the frame tube H¹
by the spring f, acting to push it forward and bearing against an adjustable
abutment (g) as before described. When the treadle is depressed a tension is
produced in each part of the chain D, the resultant of which tensions, approxi-
mately bisecting the angle formed between the parts of the chain in running
over the pulley, is designated by C and in its turn may be resolved into one
force d, radial to the guide B, and one force tangential to the same guide.
The force d, is counteracted by the spring f, through the intermediate rod. k,
but if the pressure on the treadle increases so as to overcome the elasticity of the
spring f, the pulley E will be moved rearward, for instance into the position A,
there being thus produced in the chain D a force a greater than the force a,
which denotes the tension before the compression of the spring. The guide B is
given such a shape that the pulley E will slide rearward as the pressure on the
treadles increases. The action of the notches of the guide will evidently be iden-.
tical with that in the arrangement previously described.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed I declare that what I claim is:
1. In combination with a velocipede having oscillating treadles and drive
chains or cords passing over pulleys mounted on the treadle so as to admit of
increasing or decreasing the velocity ratio of the gearing by varying the angle
formed by the chain or cord and treadle, a spring of some form or other mounted
on the frame and connected with the sliding fastening for the chain or cord on:
the frame, said spring being adapted up to a certain limit (determined by some
adjustable abutment) to tend to move the aforesaid fastening in the direction
for increasing the velocity-ratio of the machine but to yield to increasing pres-
sures on the treadles in the lower positions of the latter, and allow the fastening
to move in the opposite direction and notches on the aforesaid guide, all sub-
stantially as described and operating as set forth..
+
2. In combination with a velocipede having oscillating treadles. and .drive-
chains or cords passing over pulleys adapted to be shifted on the frame of the

page_text: velocipede so as to admit of increasing or decreasing the velocity-ratio of the
gearing by varying the angle formed by the chain or cord and treadle, a spring
of some form or other mounted on the frame and connected with the sliding
fastening for the pulley on the frame, said spring being adapted to move the
aforesaid pulley in the direction for increasing the velocity-ratio of the machine
but to yield to increasing pressures on the treadle in the lower positions of the
latter, and allow the pulley to move in the opposite direction, and notches on the
aforesaid guide, all substantially as described and operating as set forth.
Dated this 1st day of Maal 1800
HERBERT HADDAN & Co.,
Agents to Applicant.
18, Buckingham Street, Strand, W.C., London.
HERBERT HADDAN & Co.,
Agents to Applicant.
18, Buckingham Street, Strand, W.C., London.