Improvements in Frictional Gearing.
Year: 1888

page_text: Improvements in Frictional Gearing.
I, GEORGE FRANK EVANS, a resident of Somerville, County of Middlesex and
State of Massachusetts, United States of America, Machinist, 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 "Improvements in Frictional Gearing," so called, since it
may be employed in connection with pulleys actuated by surface friction only to
transmit and convey motion from one line of shafts to another, in lieu of employing
toothed gearing either spur, miter, or bevel gears, as circumstances may require."
This invention consists primarily in an endless belt, which loosely encircles one of
two cooperating pullies, the peripheries of the latter not being in contact, but
sufficiently close to grip the endless band which passes between them
be more fully hereinafter described.
as will
Further this invention consists of mechanism by which one pulley may be actuated
and caused to approach, or be removed from the other to produce activity or
inactivity of the driven pulley, as may be desired.
The drawings annexed represent in Fig. 2, a frictional gearing embodying my
invention, as applied to two straight faced pulleys in elevation and mounted upon
parallel shafts. Fig. 2. represents a diagram showing the forces operating in this
frictional gearing, Fig. 3 is a side view and Fig. 4 a front view of mechanism for
adjusting one pulley with respect to the other. Fig. 5 is a plan and side view of the
operating cam enlarged. Fig. 6 is an end and side elevation of the journal box.
Fig. 7 is a sectional view of the lower end of the hanger in Fig. 3.
In said drawings Fig. 1 represents two straight-faced pulleys 2, 3 mounted
respectively upon the shafts 4, 5, in parallelism, of which 4 is the main actuating one; the

page_text: driving pulley 2 is a rimmed pulley, so called, with flanges 6, 6. Loosely encircling
the larger pulley 2 is disposed an endless belt 7, which passes between said pulleys
and is gripped thereby being caused to do so by means of adjusting mechanism,
hereinafter described, the surface of the pulleys not being in contact.
The principle of this frictional gearing is illustrated in the diagram Fig 2. The
diametrical line shows the points of contact of the belt 7, when the pulleys are
idle, but little pressure remaining upon the belt. The driver is shown at A, the
driven pulley at B. The oblique line bb, shows the points of contact of the belt,
when the pulleys are in motion. The energy of the driver A is transmitted to the
outer face of the belt and thence forced reversely towards the diametrical line a a.
In this way the power from the driver A is directed obliquely across the axis of the
driven pulley and produces a thrust upon the latter, which causes it to revolve.
When the thrust from the driver A is in direction of the line a a diametrically of
the driven shaft and its pulley B, no rotation is produced.
The mechanism for shifting one pulley toward or away from the other I have
represented in Figs. 3 and 4, as applied to two straight faced pulleys 2, 3, the upper
shaft carries the driver, the lower one 5 the driven pulley 3. Both shafts are
suitably journaled in twin hangers 13, the lower shaft being adjustable vertically to
enable the pulley 3 and shaft 5 to become inactive, if desired.
This vertical movement is accomplished by aid of a pair of circular cams 14,
operated by levers 15 and united by a connecting rod 16; whereby simultaneous and
equal adjustment of both ends of the shaft are effected. Said cams, centrally bored,
are mounted upon circular studs 17 upon the lowermost parts of the hangers 13,
which studs are furnished with screw-threaded pins 18, provided with nuts 19.
The cams are mounted upon the studs 17 and secured by fastening nuts 19.
The journal boxes 20 are shown in Fig. 6 and are circular in cross-section midway or
at that part where they rest upon the hanger. To secure them upon the latter and
yet permit of their having vertical adjustment, I have cast or otherwise formed upon
the underside thereof two arms 21, the ends of which are reversely and obliquely
formed at 23, see Fig. 6. These oblique end faces are adapted to coöperate with and
slide upon the can surfaces 24 formed on one side of the cams 14. By this
arrangement of parts it will be seen, that the boxes 20 by means of the short
arms 21, which straddle the hangers rest entirely upon the cams. Furthermore said
arms secure the boxes upon the hangers and yet allow of vertical movement to
the boxes and shaft; said movement is produced by the semi-rotary movement of
the cams.
Since the latter rest upon the nuts 19, as fixed points, motion of the
connecting rod 16 will raise or lower the boxes 20, according to the direction in
which said rod 10 is thrust. Hence the driven pulley 3 may be rendered
active or inactive as circumstances require.
In Figs. 1,3 and 4 of the drawings one of the pulleys is shown as flanged,
however do not desire to be limited to this construction as both pulleys may
be plain straight faced ones, and work equally well.
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 :-
1st. In friction gearing mechanism, substantially as described, by which motion
is communicated between two parallel shafts, the combination with two straight-
faced pulleys and their shafts, of a loose endless band encircling one pulley and
adapted to be gripped by both pulleys, all operating in the manner, substantially
as and for purposes herein set forth and described.
2nd. In frictional gearing of the class described, the combination with two pullies,
the surfaces of which are in close proximity, but not contiguous and the endless band
which loosely encircles one pulley and passes between the two pulleys, of the adjusting
mechanism, composed of the boxes vertically movable in the hangers and the
operating cams, whereby the pulleys are caused to approach or separate one from
the other, substantially as and for purposes herein specified.

page_text: 3rd. The combination with the loose band 7 and the pulleys, one flanged, which
grip the same, of the operating mechanism composed of the cams 14, the movable
boxes 20 with arms 21, the hangers 13 straddled by the latter, and the actuating
lever rods 15, 16, all substantially as herein described.
4th. In combination with the hangers 13 provided with the studs 17, screw-
14 mounted upon
threaded pins 18 and the fastening nuts 19, the operating cams
said studs and the movable boxes 20 resting upon the cams and actuated
thereby, substantially as set forth.
Dad Boston State of Massachusetts ILSA this 2nd day of October 1888.