IMPROVEMENTS IN THE CONSTRUC- TION AND WORKING OF SAW FRAMES
Year: 1861

page_text: LETTERS PATENT to Thomas Greenwood, of Leeds, in the County of
York, Machinist, for the Invention of "IMPROVEMENTS IN THE CONSTRUC-
TION AND WORKING OF SAW FRAMES."
Sealed the 12th September 1861, and dated the 24th April 1861.
PROVISIONAL SPECIFICATION left by the said Thomas Greenwood at
the Office of the Commissioners of Patents, with his Petition, on the
24th April 1861.
I, THOMAS GREENWOOD; of Leeds, in the County of York, Machinist, do
hereby declare the nature of the said Invention for "IMPROVEMENTS IN THE
CONSTRUCTION AND WORKING OF SAW FRAMES," to be as follows:-
The chief object of this Invention is to effect an economy in the construc-
tion and in the setting up of machinery for sawing wood. To this end, instead
of working the saw frame by the aid of the usual appliances of a crank shaft
driven by a strap and pullies from the motive-power engine, and a fly wheel
for equalizing the motion of the crank shaft, I mount a steam cylinder on the
top of the standards, which are intended to carry the saw frame, and connect
the saw frame directly with a pendent rod or rods from a piston of the steam
cylinder, so that the traverse of the piston will impart a direct action to the
saw frame. This will avoid the necessity for providing a more extended foun-
dation than is required to carry the standards of the saw mill, and also simplify
the construction of the mechanism.
Another improvement which I propose to effect is to draw back the saw
blades after they have made their cut from contact with the wood under opera-

page_text: tion, so that the frame may be clear of the wood during its ascent. In order
to effect this I mount the guides in which the saw frame slides on trunnions,
which project through the side standards and are secured thereto. Upon these
trunnions the guides are free to swing, and with them the saw frame, without
its up and down motion being interfered with. The lower ends of the guides
I connect to the piston of a horizontal steam cylinder, or to a crank lever
operated by a rotating cam or equivalent mechanism for imparting a rocking
motion to the guides. By drawing back the guides out of, say a vertical line,
immediately the saw frame has completed its cut, and retaining them in that
position until the saw frame has attained the position proper to renew the cut,
(at which time it must assume its normal position,) the injurious friction now
put on the saw blades on their return motion will be avoided, and the saw mill
will consequently be enabled to run much longer than heretofore without the
saws requiring to be reset.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Thomas Greenwood in the Great Seal Patent Office on the
24th October 1861.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
GREENWOOD, of Leeds, in the County of York, Machinist, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-fourth day of April, in the year of our Lord One
thousand eight hundred and sixty-one, in the twenty-fourth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
Thomas Greenwood, Her special license that I, the said Thomas Greenwood,
my executors, administrators, and assigns, or such others as I, the said Thomas
Greenwood, 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
Íslands, and Isle of Man, an Invention for "IMPROVEMENTS IN THE CONSTRUCTION
AND WORKING OF SAW FRAMES," upon the condition (amongst others) that I, the
said Thomas Greenwood, by an instrument in writing under my hand and seal,
should particularly describe and ascertain the nature of the said Invention,
and in what mauner the same was to be performed, and cause the same to
be filed in the Great Seal Pateut Office within six calendar months next and
immediately after the date of the said Letters Patent.

page_text: NOW KNOW YE, that I, the said Thomas Greenwood, do hereby declare
the nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement, reference being had to the Drawings hereunto annexed, and to the
letters and figures marked thercon (that is to say)
The chief object of this Invention is to effect an economy in the construc
tion and in the setting up of machinery for sawing wood. This I propose to
effect by giving more compactness to the mechanism, and thus enabling it to
be set up on a smaller foundation than is at present required to ensure the
stability of sawing machinery of equal working capacity. Thus, instead of
working the saw frame by the aid of the usual appliances of a crank shaft
driven by a strap and pullies from the motive-power engine, and a fly wheel
for equalizing the motion of the crank shaft, I set up a steam cylinder in au
inverted position on the top of the framework, within which the saw frame is
mounted, and connect the saw frame directly with the pendent piston rod or
rods of the inverted steam cylinder. The traverse therefore of the piston will
impart the requisite reciprocating motion directly to the saw frame, and avoid
the necessity for providing a more extended foundation than is required to
carry the framework of the saw mill, while at the same time this arrangement
will involve the simplifying of the construction of the mechanism.
Another improvement which I propose to effect is to draw back the saw
blades after the completion of each cut from contact with the wood under
operation, so that the saw teeth may be clear of the wood during the ascent of
the frame.
In the accompanying Drawings, Fig. 1 shews in front elevation my improved
arrangement of saw frame,. the framework being partly in section; Fig. 2 is a
side elevation with one side frame removed, so as to shew more clearly the
working parts; and Fig. 3 is a plan of part of the valve and feed motions.
A, A, are the upright side frames or standards of the machine, connected
together at top by a cross piece B, B, which is firmly bolted thereto. Set up
upon this cross piece is the inverted steam cylinder C, the piston rod Diof
which projects downwards through an opening in the casting B,. and is keyed
into a socket E. Pendent from this socket is the saw frame F,.F, which is
composed of two uprights and two. cross bars; into this. moveable frame the
saw blades are keyed in the usual manner. To the upper ends of the uprights
F, F, are secured sockets F*, F*, which correspond with the socket E, and
through these sockets a round bar E* is passed, for the purpose of sustaining
the saw frame and yet leaving it free to swing thereon., Affixed to the
opposite ends of this bar E* are the sliding pieces G and K, which fit into and

page_text: .
work up and down in suitable grooves made in the upright frames A, A, and
forming a slide parallel with the cylinder. Each end.of.the lower cross piece
of the frame F is provided with a pivot, upon which are the sliding pieces
G*, G. These sliding pieces fit into and work in vertical grooves formed in the
two upright slides or guide plates H, H, which slides are mounted in horizontal
guides on the inner face of the standards A, A, to admit of their receiving a
to-and-fro motion, for the purpose to be presently explained. I is a cross
piece uniting the two slides H, H; this cross piece is cast with a socket, into
which the end of the piston rod of a small steam cylinder J is keyed. The
cylinder J is supported at the back of the frame by a cross piece A*, which is
bolted to the lower part of the framework, and it is intended to move. the
slides H to and fro on their guides, and by that means to rock the saw frame
on its fulcrum rod E*, so as to keep the teeth of the saw blades up to their
work during the down stroke of the saw frame, and draw them away from the
work at the completion of every such stroke. This arrangement therefore will
enable the saw frame to ascend to repeat the down stroke without the points
of the teeth being drawn as heretofore over the work.
The to-and-fro motion of the slides H for accomplishing this result will
require to be very slight; the stroke therefore of the piston of the cylinder
will be proportionately short, and to prevent any undue movement of the slides
stops L, L, are cast on the upright frames A, A, whereby the traverse motion
of the slides H, H, will be effectually limited.
The sliding pieces K (see Fig. 2) are shaped so as to form a cam and act
against two friction bowles mounted on the upper and lower extremities of a
T-shaped rocking lever M; this lever is keyed upon a horizontal shaft M',
To the lateral arm
which rocks in suitable journals in the standards A, A.
of this lever M is jointed the lower end of a connecting rod N, the upper
end of which is jointed to an arm keyed upon a rock shaft O. This rock shaft
carries another arm, which is connected to the valve spindle P of the steam
cylinder C. On the rock shaft M¹ of the lever M is keyed an arm M² (sce
Fig. 3), which carries a stud at its extremity. This stud takes into a small
sliding piece, working in a slot in the lever Q. This lever is mounted upon a
stud fixed in the main framing. To one end of this lever (see Fig. 2) is
attached a connecting rod Q¹ for actuating the valve belonging to the small
cylinder J, and in a slot in the opposite end of the lever Q is mounted a stud,
which is attached to the upper end of a rod Q³, extending to the lever R
upon the usual feed motion S for moving forward the timber; Tis the carriage
for supporting the timber to be cut and passing it through the saw frame. As
the means for operating the carriage forms no part of this Invention, and in

page_text: fact, differs in no respect from that usually employed for the purpose, it will
be unnecessary to explain its action further than that it is dependent for its
action on the up and down traverse of the cam K, which as it passes the
bowles on the rock lever M, and gives that lever a rocking motion alternately
in opposite directions, not only admits steam to the cylinder J through the
medium of the connecting rod Q" but through the connecting rod Q and lever
R, sets the feed motion S in action.
.
It should be remarked that the parts shewn in Fig. 2 are in a quiescent
position, but that when the machine is in action one or other of the bowles of
the lever M will always be presented to the cam K, and being struck by it
will ensure the valves of the two steam cylinders receiving their proper relative
motion, the one to admit steam to the cylinder C for giving the vertical motion
to the saw frame, and the other to admit steam to the cylinder J, to give to
the saw frame the requisite rocking or swinging motion, as above explained.
From the above description it will be understood that the same foundation
which supports the main framing serves also to carry the motive power ma-
chinery; the cost therefore of masonry fittings will, by the use of my improved
saw frame, be materially diminished; and further, it will be understood that by
drawing back the guides H out of, say, a vertical line immediately the saw
frame has completed its cut, and retaining them in that position until the saw
frame has attained the position proper to renew the cut (at which time it must
assume its normal position), the injurious friction now put on the saw blades
in their return motion will be avoided, and they will consequently be enabled
to work much longer than heretofore without requiring to be reset.
Having now set forth the nature of my Invention of "Improvements in the
Construction and Working of Saw Frames," 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, working saw frames by a direct action,
and imparting to the saw blades a vibrating motion, in the manner and for the
purpose above set forth.
In witness whereof, I, the said Thomas Greenwood, have hereunto set
my hand and seal, the Twenty-second day of October, in the year of our
Lord One thousand eight hundred and sixty and
THOMAS GREENWOOD. (L.S.)