AN IMPROVED RECIPRO- CATING MOTION
Year: 1867

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane, in
the County of Middlesex, for the Invention of "AN IMPROVED RECIPRO-
CATING MOTION." A communication from abroad by John Berry Page, of
New York City in the United States of America.
Sealed the 31st December 1867, and dated the 24th July 1867.
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark
at the Office of the Commissioners of Patents, with his Petition, on the
24th July 1867.
I, ALEXANDER MELVILLE CLARK, of 58, Chancery Lane, in the County of
Middlesex, do hereby declare the nature of the said Invention for "An In-
PROVED RECIPROCATING MOTION," to be as follows:-
This Invention relates to a new and improved reciprocating motion for
engines and other purposes. Its object is to convert a reciprocating motion
into a rotary, or a rotary into a reciprocating, without the use of the crank,
thereby avoiding the two dead points at each revolution with less strain and

page_text: wear of the parts. It consists in the employment of a pinion or toothed
wheel working in a double or top and bottom rack, and of an inner and outer
cam to relieve the dead points.
In the accompanying Drawings, Figure 1 is a side elevation, and Figure 2
is a transverse vertical section thereof at line x, x. Similar letters of reference
indicate corresponding parts.
A represents the bed of this machine; B, the rack frame firmly bolted
to A; C is the double rack, consisting of an upper and lower rack sliding
in V-shaped grooves in the rack frame B and connected with the piston rod P,
and I prefer connecting the piston rod solidly with the double rack C; D is
the pinion or toothed wheel working in the racks C, and secured to the main
shaft S by any convenient method. It has teeth only on about two-fifths of
its circumference, so that having travelled, say, on the lower rack into the
position seen in the Drawing the movement of the governor wheel G carries
the inner cam E which is firmly bolted upon the pinion or toothed wheel D
slightly out of the centre, when the pressure of the steam begins immediately
to act upon the inner and outer cam levers E and F, which now join with
the momentum acquired by the governor G to carry round the pinion D unti!
the latter engages with the upper rack. The inner cam E projects in front
of the pinion D in order that it may engage with the outer cam F, which is
either straight or if curved is a curve of greater radius than that of the
convexity of the inner cam E. I also prefer making the diameter of the
pitch line of the toothed wheel as well as the distance between the pitch lines
of the upper and lower racks equal to the length of the stroke of the piston,
such being I find the most economical method of applying this motion, but
this point is not essential to its useful employment. I also cut away a portion
of the pinion the outline whereof is shewn by the dotted lines d, d, for
greater economy of material and for lightness. H is the steam chest; h,
the valve rod, and h¹ the eccentric, in none of which do I claim any special
arrangement.
To convert a rotary motion into a reciprocating, as, for instance, to apply
water power to work a pumping engine, the position of the parts is reversed.
The piston rod P would in such case represent the pump rod, and the
governor G the water wheel.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Alexander Melville Clark in the Great Seal Patent Office on
the 21st January 1868.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALEXANDER
MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-fourth day of July, in the year of our Lord One
thousand eight hundred and sixty-seven, in the thirty-first year of Her reign,
did, for Herself, Her heirs, and successors, give and grant unto me, the said
Alexander Melville Clark, Her special licence that I, the said Alexander
Melville Clark, my executors, administrators, and assigns, or such others as I,
the said Alexander Melville Clark, my executors, administrators, and assigns,
should at any time agree with, and no others, from time to time and at all times
thereafter during the term therein expressed, should and lawfully might make,
use, exercise, and vend, within the United Kingdom of Great Britain and
Ireland, the Channel Islands, and Isle of Man, an Invention for "AN IMPROVED
RECIPROCATING MOTION," a communication to me from abroad by John Berry
Page, of New York City, in the United States of America, upon the
condition (amongst others) that I, the said Alexander Melville Clark, my
executors or administrators, by an instrument in writing under my, or their,
or one of their hands and seals, should particularly describe and ascertain
the nature of the said Invention, and in what manner the same was to be
performed, and cause the same to be filed in the Great Seal Patent Office
within six calendar months next and immediately after the date of the said
Letters Patent.
NOW KNOW YE, that I, the said Alexander Melville Clark, do hereby
declare the nature of the said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by the
following statement, reference being had to the Sheet of Drawings hereunto
annexed, and to the letters and figures marked thereon (that is to say):-
This Invention relates to a new and improved reciprocating motion for
engines and other purposes. Its object is to convert a reciprocating motion
into a rotary, or a rotary into a reciprocating motion, without the use of the
crank, thereby avoiding the two dead points at each revolution with less strain
and wear of the parts. It consists in the employment of a pinion or toothed
wheel working in a double or top and bottom rack, and of an inner and outer
cam to relieve the dead points.

page_text: In the accompanying Drawings, Figure 1 is a side elevation, and Figure 2
a top view or plan of this improved reciprocating motion as applied to convert
an alternate reciprocating motion into a rotary motion, and Figure 3 is a
transverse vertical section thereof at line x, x, Figure 1. Similar letters of
reference indicate corresponding parts.
A represents the bed of the machine; B, the rack frame firmly bolted
to A; C is the double rack, consisting of an upper and lower rack sliding
in V-shaped grooves in the rack frame B, and connected with the piston rod P,
and I prefer connecting the piston rod solidly with the double rack C; D is
the pinion or toothed wheel working in the rack C, and secured to the main
shaft S in any convenient manner; it has teeth only on about two-fifths of its
circumference, so that having travelled, say, on the lower rack into the position
seen in the Drawing the movement of the governor wheel G carries the
inner cam E which is firmly bolted upon the pinion or toothed wheel D
slightly out of the centre, when the pressure of the steam begins immediately
to act upon the inner and outer cam levers E and F, which now join with the
momentum acquired by the governor G to carry round the pinion D until the
latter engages with the upper rack. The inner cam E projects in front of
the pinion D in order that it may engage with the outer cam F, which is either
straight or if curved is a curve of greater radius than that of the convexity of
the inner cam E. I also prefer making the diameter of the pitch line of the
toothed wheel as well as the distance between the pitch lines of the upper and
lower racks equal to the length of the stroke of the piston, such being I find
the most economical method of applying the motion, but this point is not
essential to its useful employment. I also cut away a portion of the pinion,
the outline whereof is shown by the dotted lines d, d, for greater economy of
material and for lightness. H is the steam chest; h, the valve rod, and h¹
the eccentric, in none of which do I claim any special arrangement.
To convert a rotary motion into a reciprocating, as, for instance, to apply
water power to work a pumping engine, the position of the parts is reversed.
The piston rod P would in such case represent the pump rod, and the
governor G the water wheel.
Having described the nature of this Invention, and the manner of per-
forming the same, I declare that what I claim as the Invention to be protected
by the herein-before in part recited Letters Patent is,-
First, the double rack C in combination with the piston rod P or its
equivalent, substantially as herein set forth in combination with the toothed
wheel D and main shaft S, substantially as above set forth and for the purpose
described.

page_text: Secondly, the inner and outer cams E and F, or their respective equivalents,
in combination with the governor wheel G and piston rod P, or their respective
equivalents, all substantially as herein shown and described.
Thirdly, the inner and outer cams E and F, or their respective equivalents,
in combination with the double rack C and toothed wheel D, substantially as
herein shown and described.
In witness whereof, I, the said Alexander Melville Clark, have hereunto
set my hand and seal, this Twenty-first day of January, in the year
of our Lord One thousand eight hundred and sixty-eight.
A. M. CLARK. (L.B.)