Improvements in or relating to Variable Speed Driving Gear.
Year: 1898

page_text: Date of Application, 15th Mar., 1898
Complete Specification Left, 15th Dec., 1898-Accepted, 11th Mar., 1899
PROVISIONAL SPECIFICATION.
Improvements in or relating to Variable Speed Driving Gear.
I, CHARLES, M. JOHNSON, of 22, Laurence l'ountney Lane, in the City of London,
Mechanical Engineer, do, hereby declare the nature of this invention to be as
follows:-
This invention relates to variable speed driving gear for various purposes, but
as it is particularly suitable for self-propelled vehicles, I will describe it as so
applied.
21
A well known device at the present time comprises, two conical pulleys with the
large end of one corresponding to the small end of the other, and connected by
a belt; this arrangement has the draw-back that there is considerable increase
of friction upon the belt.
t
In carrying out my present invention I employ such an arrangement as above
described of cone pulleys, but instead of making the cones in the, ordinary fashion
I make the pulleys as step pulleys, each succeeding step of the same pulley being
connected by an inclined portion. By this means I have the facility for moving
the belt from one step of the pulley to any of the others, but when the belt is in
its position and actually driving it runs upon a plain or round faced pulley as
required, thus combining the advantages of the plain cone pulley with the advan-
tages of separate pulleys, or step, pulleys and obviating the disadvantages of both.
Dated this 15th day of March 1898.
BOULT & WADE,
Agents for the Applicant.
Improvements in or relating to Variable, Speed Driving Gear.
I, CHARLES M. JOHNSON, of 22, Laurence Pountney Lane, in the City of London,
Mechanical Engineer, 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:-
This invention relates to variable-speed driving-gear.. A wellknown type, of
driving-gear, commonly employed hitherto comprises two smoothly-coned pulleys
operatively connected by a band or belt, the large end of one pulley lying opposite
the small end of the other; this arrangement possesses the disadvantage that the
belt has always the tendency to travel laterally along the pulleys towards the
larger end of each so as to become slewed out of the plane in which it is desired
that it should run, and puts stress upon the shafts and upon any device which
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page_text: might be used to counteract such tendency, thus impairing, materially, the
efficiency and durability of the apparatus. According to the present invention
two coned pulleys are employed, but instead of making the cones with a profile
curved in a continuous sweep from one end to the other or as conical frustums,
they are made with substantially cylindrical surfaces of different diameters, con-
nected and made to merge smoothly into one another by intermediate tapered
portions of a conical form or of a concave or convex conoidal form. With this
improved form of pulley the belt can be moved from one cylindrical portion of
the pulley to any of the others very readily, whilst when it is in any of its several
driving-positions, it runs upon a cylindrical surface which may be plain-faced
or round-faced as required, like a common belt-pulley; thus the advantages of a
plain coned pulley are combined with the advantages of a step pulley or series
of separate pulleys, whilst the disadvantages of both those constructions are
obviated.
The improved construction above referred to affords a means of attaining a
further object of this invention which is the employment in variable speed-gear
of a belt which in any one of the series of positions in which it runs, at the
desired different speeds, is taut and nevertheless capable of being shifted laterally
with ease to vary the speed as required, because the intermediate conical or conoidal
portions of the improved pulley can be of such diameter, relatively to the cylindrical
portions, as to enable it to slacken itself while it is being shifted from one cylin-
drical portion to another. Further by taking the ends of a pair of pulleys thus
formed they can be used instead of two pairs of fast-and-loose pulleys; that is to
say if two pulleys geared together by a belt passing round substan-
tially cylindrical portions thereof have each a tapered extension into which
the cylindrical portion merges smoothly, the belt can be made to run loosely with-
out exerting any driving effort by shifting it off the cylindrical portion and letting
it run on the tapered extensions, provided that the diameters of the latter are made
to be such that the belt is not caused to grip them; the belt, by reason of the
tapered portions being merged smoothly into the substantially cylindrical portions
can readily be shifted back on to the latter when it is desired that the gear shall
⚫become operative again.
In the accompany diagrams, Figure 1 shows in plan a pair of pulleys formed
according to this invention and operatively connected by an open belt; and
Figure 2 is an end elevation of the apparatus illustrated in plan in Figure 1.
Figure 3,is a side elevation and
Figure 4 an end elevation showing two pulleys each with a tapered extension,
operatively connected by a belt and arranged to serve as the equivalent herein-
before referred to of two pairs of fast-and-loose pulleys.
Like letters indicate like parts throughout the drawings.
With reference first to Figures 1 and 2 a frame A supports in bearings A¹, two
spindles B and C, upon which respectively are pulleys D and E. Each of the
pulleys D and E is tapered and the smaller end of one pulley is opposed to the
larger end of the other as is customary. The profile or outline of each pulley is
made up of substantially cylindrical portions such as D D D D7 or E¹ 13 E E7
of different diameters connected and made to merge smoothly into one another by
intermediate tapered portions D D D or E E E of a conical form as illustrated.
A belt F operatively connects the pair of pulleys and may be caused to pass with
ease from one pair of cylindrical surfaces D5 E to another pair such as D E7 along
the intermediate conical portions D E. The cylindrical portions such as D E¹ are
shown in the drawing as having a slightly rounded surface, by which, as usual,
it is ensured that the belt shall run centrally upon them; when it runs upon these
parts it has no tendency to travel out of the plane of its proper running position,
and therefore, is not stressed or caused to render the gear inefficient by setting up
undue friction in the belt or bearings, or otherwise.
Although it is preferred to use these improved pulleys in related pairs in the
manner indicated in the drawing, one such pulley may be employed in combina-

page_text: tion with a long cylindrical pulley parallel with it, the belt passing round both
having a jockey pulley or other tightener to take up the slack which in such a case
would be necessary.
Instead of gearing the two pulleys D and E by means of the belt F they might
be frictionally geared by means of an intermediate friction pulley introduced
between them and adapted to bear upon any of the pairs of the related cylindrical
surfaces such as D5 E5.
With reference now to Figures 3 and 4 two pulleys D and E mounted in
bearings A are geared together by a belt F as shown; the pulley D has a substan-
tially cylindrical portion 1) and a tapered extension De like the left hand end of the
pulley 1 of Figure 1, whilst the pulley E has a substantially cylindrical portion El
and a tapered extension E like the left-hand end of the pulley E in Figure 1.
The belt F when it runs upon the substantially cylindrical portions D' E' of
Figure 3 will drive the one pulley from the other, but if it be desired to stop this
driving action the belt is shifted laterally in the direction of the arrow Figure 3
on to the tapered extension upon which it will hang slack as indicated by dotted
lines in Figures 3 and 4 so as to transmit no driving effort. This arrangement
thus becomes the equivalent of two pairs of fast-and-loose pulleys as a starting
and stopping device..
Having now particularly described and ascertained the nature of my
invention and in what manner the same is to be performed, I declare that what
I claim is:-
1. In variable-speed driving-gear a pulley having substantially cylindrical
portions of different diameters and one or more tapered portions connecting them
for the purpose described.
2. A variable-speed gear comprising two pulleys of the kind described having
co-acting pairs of substantially cylindrical portions of such relative diameters that
a beit will be equally taut on all such pairs substantially as described.
3. In variable-speed driving-gear the combination of two pulleys such as, are
described in the first claiming clause hereof the larger end of one such pulley
facing the smaller end of the other.
4. In belt driving-gear the combination of two pulleys each having a substan-
tially cylindrical portion and a tapered extension thereof into which the cylindrical
portion merges smoothly for the purpose described with reference to Figures 3
and 4 of the accompanying drawings.
Dated this 10th day of December 1898.