AN IMPROVEMENT IN THE CONSTRUCTION OF SCREW GILL MACHINERY
Year: 1872

page_text: LETTERS PATENT to Arthur Greenwood, of Leeds, in the County of
York, Machine Maker, for the Invention of “AN IMPROVEMENT IN
THE CONSTRUCTION OF SCREW GILL MACHINERY."
Sealed the 26th November 1872, and dated the 6th June 1872.
PROVISIONAL SPECIFICATION left by the said Arthur Greenwood at
the Office of the Commissioners of Patents, with his Petition, on
the 6th June 1872.
I, ARTHUR GREENWOOD, of Leeds, in the County of York, Machine
Maker, do hereby declare the nature of the said Invention for "AN
IMPROVEMENT IN THE CONSTRUCTION OF SCREW GILL MACHINERY," to be as
follows:-
This Invention relates to improved means for lifting the gill bars or
fallers from their lower to their upper screw.
The lifting cam which I employ is of the usual form with this
exception, viz., that instead of its being reduced in thickness to enter
the thread of the upper screw, it is left somewhat broader than the
width of the space or thread of the upper screw. To allow this cam
(which in its rotation enters the space occupied by the overlying or

page_text: upper screw) to clear the upper screw in its rotation, a portion of the
thread in the upper screw is removed to form a recess for the cam to
enter while passing the upper screw. The advantage of providing a
broad cam is that the faller end cannot catch or wedge itself in the
thread of the upper screw and thereby cause breakages, as is so often the
case in the usual construction of screw gills. The back part of the
upper screws may be left solid and only shaped on their inner face to
the pitch of the thread. The faller in its upper motion is steadied by
spring guides or lever guides, as in the ordinary arrangements of screw
gills. The solid back parts of the upper screws may be of an equal
diameter with the remainder of the screws, or may be made larger in
diameter so as to give additional surface of the gill bar or faller whilst
rising. They may be applied in the form of a loose collar, or may be
made in halves so as to be applied to existing machinery of the ordinary
pattern or construction.
Gill screws constructed upon the above described principle may be
applied both to single and to double (or intersecting) screw gill preparing
machinery.
SPECIFICATION in pursuance of the conditions of the Letters Patent
filed by the said Arthur Greenwood in the Great Seal Patent Office
on the 6th December 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ARTHUR
GREENWOOD, of Leeds, in the County of York, Machine Maker, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Sixth day of June, in the year of our
Lord One thousand eight hundred and seventy-two, in the thirty-fifth
year of Her reign, did, for Herself, Her heirs and successors, give and
grant unto me, the said Arthur Greenwood, Her special licence that I,
the said Arthur Greenwood, my executors, administrators, and assigns,
or such others as I, the said Arthur Greenwood, my executors, adminis-
trators, 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,

page_text: within the United Kingdom of Great Britain and Ireland, the Channel
Islands, and Isle of Man, an Invention for "AN IMPROVEMENT IN THE
CONSTRUCTION OF SCREW GILL MACHINERY," upon the condition (amongst
others) that I, the said Arthur Greenwood, my executors or adminis-
trators, 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 Arthur Greenwood, do hereby
declare the nature of my 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 Drawing
hereunto annexed, and to the letters and figures marked thereon (that is
to say):
:-
This Invention relates to improved means for lifting the gill bars or
fallers from their lower to their upper traversing screws.
The lifting cams which I employ are of the usual form, with this
exception, viz., that instead of their being so reduced in thickness as to
permit of their freely entering the thread of their respective upper
screws, their thickness is somewhat in excess of the width of the space
or thread of the upper screw. To allow these broad cams (which in
their rotation must from their proximity to the upper screws enter the
space occupied by these screws) to clear the upper screws and rotate
freely, a portion of the thread of each upper screw is removed, and
thereby recesses are formed for the lifting cams to enter while passing
the upper screws.
In the accompanying Drawing Fig. 1 shews in side elevation so much
of an upper and lower gill screw as will serve to explain the nature of
this Invention; and Fig. 2 is a transverse section of the same shewing
the gill bars in place and resting on their slides.
A is the upper or forward traversing screw, and B the lower screw,
which gives the back traverse to the gill bars or fallers C, C. B' is one
of a pair of broad cams for lifting the gill bars from the slides D to the
slides E when they have completed their back traverse. For the
purpose of enabling these cams to clear the upper screws during their

page_text: rotation, a portion of the thread of the upper screws is cut away, as
shewn by dots at A'. As the upper and lower screws rotate at the
same speed, the recesses thus formed will be brought round to meet
respectively the cams B', and thus afford the requisite space for the
rotation of the cams. The advantage of providing broad cams is that
the faller ends cannot catch or wedge into the thread of the upper
screws and thereby cause breakages, as is so often the case in the usual
construction of screw gills. The back parts A³ of the upper screws,
forming the terminations of the threads, may be left solid, and only
shaped on their inner faces to the pitch of the thread. The fallers in
their upward motion are steadied by spring guides or lever guides, as in
the ordinary arrangements of screw gills. The solid back parts of
the upper screws may be of an equal diameter with the remainder of the
screws, or may be made larger in diameter so as to give additional
surface to the gill bars or fallers whilst rising. These back parts may
be applied in the form of loose collars, or may be made in halves
so as to be applied to existing machinery of the ordinary pattern or
construction.
Gill screws constructed upon the above described principle may be
applied both to single and to double (or intersecting) screw gill preparing
machinery.
Having now set forth the nature of my Invention of "An Improvement
in the Construction of Screw Gill Machinery," and explained the manner
of carrying the same into effect, I wish it to be understood that under
the above in part recited Letters Patent I claim, the lifting arrangement
above described, whereby the gill bars or fallers are prevented from
catching or wedging into the threads of the upper screws.
In witness whereof, I, the said Arthur Greenwood, have hereunto
set my hand and seal, the Fourth day of December, in the year
of our Lord One thousand eight hundred and seventy-two.
ARTHUR GREEN WOOD. (L.S.)