An Improved Cam Mechanism applicable for Converting Rotary into Reciprocating Motion and vice versa.
Year: 1890

page_text: Date of Application, 11th Oct., 1890-Accepted, 13th Dec., 1890
COMPLETE SPECIFICATION.
An Improved Cam Mechanism applicable for Converting Rotary
into Reciprocating Motion and vice versa.
We, PATRICK BLACKIE of Redfern, near Sydney, in the Colony of New South
Wales, Engineer, and JOHN NISBET of Coolabah in the said Colony, Grazier, 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 an improved mechanical motion which has been devised
specially to provide compact gear for converting rotary into reciprocating motion and
at the same time multiplying or increasing the speeds or number of strokes of the
one in relation to the number of revolutions of the other. While this motion is
suitable for converting rotary into reciprocating motion yet it may be found useful for
the conversion of reciprocating into rotary motion if the latter be provided with means
for overcoming dead points or dead centres. This motion is especially useful for con-
verting the motion of the revolving spindle into the reciprocating motion of the
cutters in sheep shearing machines but it may also be applied in machines for
other purposes.
of a inale
This improved mechanical motion is comprised in the combination and arrangement
with a female star or peculiarly recessed disc or as we term it "femestar
or tongue or as we term it a diametang" gearing in and with the recesses of tho
female star and adapted the former to revolve and the latter to have reciprocating
motion.
But in order that this invention may be clearly understood we will now describe
the same with reference to the drawings herewith in which
Figures 1 and 2 are section and plan of the improved mechanical motion the
reciprocations being to the revolutions as three to one.
Figure 3 is a face view of the femestar and a section of the diametang of the
same.
Figures 4 and 5 are diagrammatic plans showing designs or draughts of the improved
mechanical motion and
Figures 6 and 7 are views similar to that in Figure 3 but in these cases the ratios
of speed of reciprocations and revolutions are five to one and seven to one respec-
tively A is revolving spindle-B reciprocating lever-C femestar-D diametang-
Alis bearing-B' fulcrum-C outer angles- inner angles-D' extremes.
In operation should spindle A be revolved the lever B will be reciprocated on
fulcrum B' by the action of the inner angles C upon the curved surfaces of the
diametang D impelling it to turn or revolve but as it cannot move but horizontally it
is thrust backwards and forwards by the wedging action of the contact of said inner
angles C
The peculiar recesses of the femestar are set out as follows:-The stroke and length
of the diametang being determined we draw two straight lines a and b at right
angles and upon one of them a set out the length of the diametang as at
points c. Now with a radius equal to half the length of diametang less half
the stroke a circle d termed the "motion circle" is drawn which circle is equally
divided into the same number of parts (as three, five, seven, &c. or other uneven
These divisions one of which
number) as angles are required in the femestar.
must be upon line bat right angles to the length of the diametang are marked e
and fix the internal points of the femestar. The curve of the diametang is now
ascertained by drawing a circle cutting the extremes or points c and the two of
the points e respectively nearest to points c on either side of line and thus
obtaining centre . With the same radius and from centres fequidistant from

page_text: the main centre and equidistant from each other the remaining curves of the
femestar and diametang are drawn and the whole finished with a circumference g
drawn through the outside points where the circles meet. The design or draught
just described is correct where the reciprocation is in a straight line and is also suitable
where reciprocation is a rocking motion from a near centre as in small gears in which
case the necessary concavity of the disc is small and would give little variance.
where there is longer reciprocation or more concavity of disc in designing and
draughting the femestar allowance would have to be made for the same.
But
It is to be understood that we do not confine ourselves to any particular size or
construction of our improved mechanical motion so long as the nature of our
invention be retained.
Having now particularly described and ascertained the nature of our said inven-
tion and the manner in which the same is to be performed we declare that
what we claim is :-
First. The improved mechanical motion comprised in the combination and
arrangement with a peculiarly recessed disc or femestar (adapted to revolve) of a
tongue or male or diametang (adapted to reciprocate) gearing in and with the recesses
of said femestar substantially as herein described and explained.
Second. The improved mechanical motion having a disc or femestar and male or
diametang whose construction or configuration is determined in the manner and for
the purposes substantially as herein described and explained and as illustrated in
the drawing.
Third. The improved mechanical motion constructed and arranged substantially as
herein described and explained and as illustrated in the drawing.
Dated this Twenty-first day of August One thousand icht hunna and
ninety.
PATRICK BLACKIE.
JOHN NISBET.
Wm. P. Thompson & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicants.