IMPROVEMENTS IN APPARATUS FOR STRAINING PULP
Year: 1872

page_text: LETTERS PATENT to John Wood and Robert Wood, of Leith, in the
County of Mid Lothian, North Britain, Engineers, for the Invention
of TnAme
Sealed the 22nd April 1873, and dated the 24th October 1872.
PROVISIONAL SPECIFICATION left by the said John Wood and Robert
Wood at the Office of the Commissioners of Patents, with their
Petition, on the 24th October 1872.
We, JOHN WOOD and ROBERT WOOD, of Leith, in the County of
Mid Lothian, North Britain, Engineers, do hereby declare the nature
of the said Invention for "IMPROVEMENTS IN APPARATUS FOR STRAINING PULP,"
to be as follows, that is to say :—
This Invention relates to improvements whereby pulp straining
apparatus is made more efficient, is simplified in construction and action,
and rendered less liable to get out of order than existing apparatus for
the same purpose.
The kind of apparatus to which the improvements are applied is one
in which a strainer casing in the form of a prism with four or other

page_text: convenient number of perforated or permeable sides, and placed hori-
zontally, revolves about a horizontal axis in a trough, into which the
pulp to be strained is poured. The pure pulp is drawn into the casing
and passes off from one end by a hollow trunnion; and heretofore the
action has been produced by a species of bellows, or by discs or
equivalent details working inside the casing with a short rapid re-
ciprocation.
By the present Invention the bellows or equivalent working parts are
removed from the interior of the strainer casing, and the necessary action
is produced by means of a pump, the cylinder of which is fixed on a
stationary support outside of the casing, and also by preference outside
of the trough. A hollow trunnion is fixed to the strainer casing at the
end opposite to the discharge end, and passes through a stuffing box in
the end of the trough, outside of which it has fixed on it the spur wheel,
The trunnion
by means of which the revolving motion is imparted.
extends beyond the spur wheel and into a stuffing box in the inner
end of the pump cylinder, or in a pipe communicating with the pump
cylinder, when such cylinder is not placed horizontally or close to the
trough, and the action of the pump piston or plunger is to alternately
suck and force the liquid out and in through the trunnion. The trunnion
communicates directly with an enlarged tube of a circular or other
convenient cross section placed centrally in the strainer casing, and
extending from what may be termed the pump end of the casing nearly
to the other end. This central tube has a number of perforations in its
sides and a perforated disc or plate covers the end of it furthest from
the pump, whilst there is also a perforated plate or cap fitted over the
inner end of the outlet trunnion.
With these improved arrangements the reciprocating movement of
the liquid inside the casing is rendered more radial and less longitudinal
than in former strainers, so that there is much less tendency to make
the strainer casing reciprocate longitudinally and thereby cause rapid
wear of its journal collars.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Wood and Robert Wood in the Great Seal
Patent Office on the 22nd April 1873.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, JOHN
WOOD and ROBERT WOOD, of Leith, in the County of Mid Lothian,
North Britain, Engineers, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-fourth day of October, in the
year of our Lord One thousand eight hundred and seventy-two, in the
thirty-sixth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto us, the said John Wood and Robert Wood, Her
special licence that we, the said John Wood and Robert Wood, our
executors, administrators, and assigns, or such others as we, the said
John Wood and Robert Wood, our 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 "IMPROVEMENTS IN APPARATUS FOR
STRAINING PULP," upon the condition (amongst others) that we, the said
John Wood and Robert Wood, our executors or administrators, by an
instrument in writing under our, 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 we, the said John Wood and Robert Wood,
do hereby declare the nature of our said Invention, and in what manner
the same is to be performed, to be particularly described and ascertained
in and by the following statement in writing, reference being had to the

page_text: and is rendered less liable to get out of order than existing apparatus for
the same purpose.
The kind of apparatus to which our improvements are applied is one
in which a strainer casing in the form of a prism with four or other
convenient number of perforated or permeable sides, and placed hori-
zontally, revolves about a horizontal axis in a trough, into which the
pulp to be strained is poured. The pure pulp is drawn into the casing
and passes off from one end by a hollow trunnion; and heretofore the
action has been produced by a species of bellows, or by discs or
equivalent details working inside the casing with a short rapid re-
ciprocation.
By our present Invention the bellows or equivalent working parts are
removed from the interior of the strainer casing, and the necessary action
is produced by means of a pump outside of the strainer casing.
:
And in order that our said Invention and the manner of performing
the same may be properly understood, we hereunto append a Sheet of
explanatory Drawings to be herein-after referred to, and representing
pulp straining apparatus as fitted with a modification of our improve-
ments.
In these Drawings the same reference numerals are used to
mark the same or like parts wherever they are repeated.
Figure 1 is a plan of the apparatus, and Figures 2 and 3 are longi-
tudinal and transverse vertical sections. The trough or pulp vat 1 is
represented as made of cast iron, and is fitted with stuffing boxes 2, 3,
at each end for the hollow trunnions 4, 5, of the strainer casing 6 to pass
through. The strainer casing 6 is framed and fitted with strainer plates
to form its sides in the usual way, and one of its hollow trunnions 4
extends into one end of a pump cylinder 7 and through a stuffing box 8
in the cylinder end. The spur wheel 9, by means of which the strainer
casing is driven in the usual way, is fixed on the trunnion 4 between
the trough stuffing box 2 and the pump stuffing box 8. The pump a
cylinder 7 is fixed on a framing 10 connected to the trough 1, and which
also carries the bearing of a revolving crank shaft 11, the crank pin 12
of this shaft being connected by the rods 13, 14, to the pump piston 15;
this pump piston is packed with cupped leathers or in any other effective
manner. The hollow trunnion 4 communicates directly with an enlarged a
tube 16 of a circular or other convenient cross section placed centrally
within the strainer casing 6, and extending from what may be termed

page_text: the
pump
end of this casing (to which end it is fixed by a flange) nearly
to the other or discharge end. Near the discharge end the tube 16 is
supported by brackets or straps 17 from the corner frame bars of the
strainer casing 6. This central tube, which is by preference made of
5 copper or brass, has a number of perforations made in its sides, and a
perforated disc or plate covers the end near the discharge trunnion 5
(and may be attached by screws to admit of removal for cleaning the
interior of the tube 16). The perforations in the tube 16 are graduated
with the view of equalising the action over its whole length, those in
the third part nearest the pump being about 3 inch in diameter and.
2½ inches apart transversely and longitudinally, whilst those in the
middle part are about ✓ inch and 1½ inches apart, and those in the
remaining third part nearly inch and 1 inch apart.
We purposed fitting a perforated cap over the inner end of the outlet
trunnion 5, but have found that it is not required.
With our improved arrangements, the comparative simplicity of which
is obvious, the reciprocating movement of the liquid inside the casing 6
is rendered more radial and less longitudinal than in former strainers, so
that there is much less tendency to make the strainer casing reciprocate
longitudinally and thereby cause rapid wear at its journal collars.
We find good results are obtainable when the strainer casing 6 makes
about ten revolutions per minute, with 300 revolutions of the crank
shaft 11 or double strokes of the pump, but it will be understood that
these speeds may be varied in practice.
A plunger working through a stuffing box in the outer end of the pump
cylinder 7 may be substituted for the piston 15 herein-before described,
and the pump may be placed in any position or situation that may be
most convenient, the cylinder 7 being connected to the stuffing box 8
by a straight or bent pipe or passage as each case may require.
Having thus particularly described our said Invention, and the manner
of performing the same, we have to state that we do not restrict ourselves
to the precise details herein described or delineated, but that what we
believe to be novel and original and claim as the Invention secured to
us by the herein-before in part recited Letters Patent is, the constructing
of pulp straining apparatus with an inner perforated tube (16), the

page_text: interior of which is in communication with a rapidly reciprocating pump
or its equivalent, substantially as herein described and delineated.
In witness whereof, I, the said John Wood, on behalf of myself
and the said Robert Wood, have hereunto set my hand and seal,
this
day of April, in the year of our Lord One thousand 5
eight hundred and seventy-three.