Year: 1899

page_text: Date of Application, 28th Sept., 1899
Complete Specification Left, 27th June, 1900-Accepted, 4th Aug., 1900
I, WILFRED ROTHIERY WOOD, of 18, Walbrook, in the City of London, Engineer,
do hereby declare the nature of this invention to be as follows:-
The present invention relates to detail improvements in mechanical stoking
apparatus such for example as is described in Specification 17179 of 1898.
In said specification the feed screw is shewn as having a constantly decreasing
taper and pitch from the outer to the inner end and the inner side walls of that
portion of the combustion chamber in which the screw rotatės, leaves or break
contact with the screw at a plane drawn approximately horizontally through the
axis thereof.
By experiment I have found that the upward feed of the fuel takes place almost
entirely on that side of the screw on which the thread rises such feed being
almost tangential and that on the descending side the fuel at times tends to cake
or accumulate and is fed forward without rising substantially, and as the pitch
and taper decrease it experiences a constantly increasing difficulty in upward
movement any tendency to which is partially impeded from the bottom by the
core or stem of the screw.
According to the present invention it is proposed that the combustion chamber
of the magazine should only be open to upward feed from a point approximately
on a horizontal plane with the axis of the screw on that side upon which the thread
rises, to a point at or slightly past that which would be formed by a plane
vertically drawn through the axis and that the screw itself or the main portion
thereof should be a helix or spiral without a core or stem except such as may
be found desirable at its outer end to which the power is applied.
Dated this 27th day of September 1800
I, WILFRED ROTHERY WOOD, of 18, Walbrook, in the City of London, Engineer,
do hereby declare the nature of this invention and in what manner the same is
[Price 8d.]

page_text: to be performed, to be particularly described and ascertained in and by the
following statement:-
The present invention relates to detail improvements in mechanical stoking
apparatus such for example as is described in the prior Specification 17179/98.
In said specification the feed screw is shown as having a constantly decreasing
taper and pitch from the outer to the inner end, and in stokers made in accord-
ance with said specification it has been customary for the inner side walls of
that portion of the coking or fuel chamber in which the screw rotates to leave
or break contact with the screw at a plane drawn approximately through the
axis thereof.
By experiment I have found that the upward feed of the fuel takes place almost
entirely on that side of the screw on which the thread rises such feed being
almost tangential and that on the descending side the fuel at times tends to cake
or accumulate and is fed forward without rising substantially and as the pitch
and taper of the screw decrease the fuel experiences a constantly increasing
difficulty in upward movement any tendency to which is partially impeded from
the bottom by the boss or stem of the screw, and at times so much power is
required to drive the screw that the caked material breaks it.
According to the present invention it is proposed that the coking or fuel
chamber of the magazine should only be open to upward feed from a point
approximately on a horizontal plane with the axis of the screw on that side
upon which the thread rises to a point at or slightly past that which would be
formed by a plane vertically drawn through the axis and that the screw itself or
the portion thereof within the coking chamber should be a helix or spiral without
a core or stem and having a gradually decreased carrying capacity.
In order that the invention may be clearly understood reference is made to
the accompanying drawings which show the present invention applied to a stoker
of the class indicated, but it is to be understood that the invention is equally
applicable to stokers with varying details of construction.
In said drawings Fig. 1 is a longitudinal section elevation of so much of the
furnace and connected parts as is necessary to show the present invention.
Fig. 2 is a sectional elevation on a larger scale on line 1-1 and Fig. 3 a
like view on line 2-2.
As shown the first or outer portion of screw A has a constant pitch and carry-
ing capacity and is without taper and is provided with a hollow internally angled
boss or stem B adapted to engage with a corresponding boss or stem C at the
outer end of the taper screw 11. The driving shaft E passes within bosses B
and C and being pinned to the latter the parts are held in operative position.
All that portion of screw D which is within the coking or fuel chamber Fis
shown in the form of a helix or spiral having a constantly decreasing carrying
capacity and without a central boss or stem the omission of which not only gives
a greater fuel space and the fuel a better chance to rise but also by doing away
with the friction between the fuel and the boss reduces very considerably the
power required to drive the screw.
To secure the upward feed of the fuel the inner side wall G of coking or fuel
chamber F upon which the screw rises leaves said screw on approximately a
plane drawn horizontally through the axis of the screw, while the wall H leaves
said screw at a point slightly past that which would be formed by a plane drawn
vertically through the screws axis. This construction not only prevents the screw
from forming cakes or balls of fuel upon its descending side but also provides a
good bearing surface for such screw throughout its entire length and prevents
any possibility of its rising from its proper position. The partial pocketing or
enclosing of the screw as described not only prevents it from rising as just
described but also by supporting the coreless spiral or helix renders it sufficiently
rigid for the purpose intended and also enables the opposite ports or tuyeres of
the fuel chamber to be brought much closer together than is usual, thus ensuring

page_text: the penetration of the draught to the centre of the fuel and securing a very
perfect coking and combustion of the same.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed I declare that what
I claim is:-
-
1. In mechanical stokers a feed screw, that portion within the furnace being
in the form of a helix or spiral having a decreasing carrying capacity substantially
as described.
2. In mechanical stokers and in combination a feed screw in the form of a
helix or spiral and a coking or fuel chamber, the inner walls of which leave said
screw at a point approximately in a horizontal plane with the axis of said screw
on the side upon which it rises and on the descending side at a point slightly
beyond that formed by a vertical plane drawn through the axis substantially as
and for the purpose set forth.
3. In mechanical stokers a feed screw having a constant pitch and diameter at
its outer end, and a boss or stem and a constant pitch and decreasing diameter
upon that portion within the coking or fuel chamber wherein it is in the form
of a helix or spiral substantially as described.
1000
PHILIP M. JUSTICE,
55 & 56, Chancery Lane, Chartered Patent Agent,
For the Applicant.