Improvements in Friction Gear for Fast Running Shafts.
Year: 1894

page_text: COMPLETE SPECIFICATION.
Improvements in Friction Gear for Fast Running Shafts.
We, CARL ALRIK HULT, of Westmannagatan 30, Stockholm, in the Kingdom
of Sweden, and OSCAR WALFRID HULT of Hummersberg, near Stockholm
aforesaid, Engineers, 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 :—
Our invention relates to friction gear of the kind in which an annular track
surrounds the shaft to be driven between which shaft and the track are applied
friction-wheels caused to rotate around the annular track by a common centre or
holder to which they are pivotted thereby rotating the shaft.
Such friction gear as hitherto constructed is not found to be suitable in cases
where it is necessary that the centreing of the shaft should be exact, for example,
for centrifugal separators, and our invention has mainly for object to so construct
the said gear that the shaft shall be supported by a yielding bearing so that it may
centre itself while revolving.
For this purpose we secure elastic rings around the friction wheels or replace the
friction wheels by elastic rings. Or we arrange the annular track so that it
constitutes an elastic ring.
To enable our invention to be fully understood we will describe how it can be
carried into practice by reference to the accompanying drawing, in which :-
Figures 1, 3 and 5 are vertical sections illustrating various arrangements of the
friction gear; and,
Figures 2, 4 and 6 are plan views of Figures 1, 3 and 5 respectively.
In the arrangement illustrated in Figures 1 and 2 the shaft A to be driven is
supported by the pivot C firmly fixed to the bottom B of the frame and serving as
a step-bearing, this pivot being provided with a pinion D, the boss of which is
extended upwards and forms a sleeve E surrounding the shaft A. The pinion D
which engages with the toothed wheel G secured on the driving shaft F, runs loose
on the pivot C, and in the sleeve E belonging thereto the shaft A freely revolves.
From the top of the sleeve E project three arms H supporting three friction
wheels 1, each freely revolving on a pivot K fixed to the arm provided on the
circumference with an elastic ring L bearing against the shaft A and the annular
track M formed by the interior of the top of the circular frame. The diameter
of the ring L is somewhat greater than the distance between the said track and
the shaft, therefore, owing to the compression, it exerts a pressure against the said
parts sufficiently strong to cause the ring to rotate when accompanying the arm H
The
around the track M and also to impart a rotary motion to the shaft A.
wheels I are arranged equidistant with relation to each other in order to support
the shaft at different points. The said wheels serve as a roller-bearing for the
shaft and at the same time to drive the latter round, and the rings by their
elasticity allow the shaft to centre itself. The bearing moves very lightly as the
pressure of the wheel 1 against the shaft or the track M is not transmitted to the
pivot of the wheel. The shaft A may, if required; be provided with a small
friction pulley corresponding to the wheels I.
The
In the modification illustrated in Figures 3 and 4 the wheels I instead of being
cach provided with an elastic ring L have a single elastic ring N, or in other words,
the track consists of an interior ring N, against which the wheels I run.
ring has a radius a little shorter than the diameter of the wheel I plus the radius
of the shaft in order that the wheels may be pressed upon by the ring and
consequently press upon the shaft. The latter is thereby allowed to centre itself,

page_text: as previously stated. Behind the ring there is an elastic packing O which prevents
the former from revolving.
In the modification illustrated in Figures 5 and 6 the sleeve E is provided with
an additional pinion P from the boss of which project arms P¹ which support a
track M corresponding to the track M in Figure 1. The pinion P runs loose on.
the sleeve E and engages with the toothed wheel G; the wheels I and the track M¹
therefore rotate in opposite directions. Owing to the said motion of the track M¹
the wheels I have a greater speed than if the track were stationary. The wheels 1
have each an elastic ring similarly to the wheels in Figure 1. We would
observe that the part of the gear, Figures 1 and 3, which imparts the rotatory
motion to the sleeve E can obviously be arranged in many different ways, for
instance, it may consist of bevel and cylindrical toothed wheels or of friction or
grooved wheels. The number of friction wheels I can be greater than three and in
lieu of the arms H the sleeve E may be provided with a flange or disc to which the
wheels I are secured. Rings may be employed in place of the wheels I, the rings
being caused to rotate by rollers a, as shewn by the dotted lines in Figure 2, fixed
to arms like the arms H, which rollers prevent the rings from coming in contact
with each other as they are located between them and are also provided with flanges
which serve to guide the rings. Similar flanges may also be provided on the track
and on the shaft. The rollers may, if required, be located within the rings so as to
run against the inner sides of the latter and the track, in the event of rings only
being used, may be either stationary or moveable.
The described arrangement of sleeve running loose on the shaft and by means of
which the friction wheels I are caused to rotate around the annular track, Figure 1,
can obviously be used without the wheels I being provided with elastic rings, that
is to say, the wheels may bear directly against the shaft A although not with the
same advantage as when elastic rings are employed as above described.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
.
1. In a friction gear comprising friction wheels located between and bearing
against the shaft to be driven and an annular track surrounding the latter and
caused to revolve around the track by the common centre or holder to which they
are pivotted thus causing the said shaft to rotate, an elastic ring such as L placed
around each wheel and which, being somewhat compressed, bears against the said
shaft and the track in order that the rings driving the shaft may serve as a bearing
therefor and that the shaft may be at liberty to centre itself, substantially as
herein before described and illustrated in Figures 1 and 2 of the accompanying
drawing.
2. The modification of the arrangement claimed in Claim I in which in lieu of
an elastic ring around each friction wheel the track consists of an elastic ring pressing
the friction wheels against the shaft to be driven and an elastic packing, substan-
tially as hereinbefore described and illustrated in Figures 3 and 4 of the accom-
panying drawing.
3. The modification of the arrangement claimed in Claim 1, in which the friction
wheels are replaced by elastic rings, which, being somewhat compressed between
the shaft to be driven and the track are caused to revolve around the track by
rollers pressing them from without or within and secured to a common centre
corresponding to that carrying the friction wheels, substantially as hereinbefore
described with reference to Figure 2 of the accompanying drawing.
4. In a friction gear of the kind referred to in Claim I a sleeve carrying the
friction wheels (provided or not with elastic rings) or by means of which the rings
referred to in Claim 3 are driven running loose on the shaft and provided with
arms or a flange to which the wheels are secured and which sleeve is driven by
means of a cog gearing, belting or friction gear, substantially as hereinbefore
'described.

page_text: 5. In a friction gear of the kind referred to in Claim 1 a moveable track carried
by arms projecting from a wheel running loose on a sleeve E, this wheel being
caused to rotate in a direction opposite to that of the sleeve, substantially as
herein before described and illustrated in Figures 5 and 6 of the acccompanying
drawing.
Du thin 14th do- of Rohruary 18GA
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicants.