Improvements in Screw Conveyors.
Year: 1895

page_text: Date of Application, 16th Mar., 1895
Complete Specification Left, 12th Dec., 1895-Accepted, 18th Jan., 1896
Improvements in Screw Conveyors.
I, DAVID RUSHWORTH, of 13 Manchester Old Road, Heaton Chapel, near
Stockport, in the County of Lancaster, Mechanical Engineer, do hereby declare
the nature of this invention to be as follows:-
―:
This invention has reference to screw conveyors, and although primarily intended
for use in conjunction with mechanical stokers for feeding or supplying the coal
or other fuel to the hoppers it may also with advantage be employed in collieries,
chemical and other works, and numerous other manufactures, for conveying or
transporting coal, minerals, ores or other inaterials or substances from one fixed
place to another as may be desired.
Hitherto screw conveyors or conveyor worms for these purposes have either been
constructed of a number of short single pitch segments attached to a solid central
shaft, or cast solid in one continuous length. In the former case, amongst other
objections, the initial cost of production is high, and the conveyor is also considerably
weakened, and in the latter case in the event of breakage or fracture of any part
of the screw it has necessitated the replacing of the whole screw, in addition to
which both forms owing to their weight have required the expenditure of consider-
able power to drive them.
This invention is designed to obviate these objections.
It consists essentially in constructing the screw or worm of the conveyor of any
required number of sections, each section being of a length equal to say two, three
or any desired number of pitches or spirals of the screw with a hollow cylindrical
body, which sections will be keyed or otherwise suitably attached to a hollow driving
shaft.
In carrying out the invention I cast or otherwise construct the sections of the
screw of a length equal to two, three or more spirals or pitches of the screw.
The
web or thread of the screw is formed on a hollow cylindrical body. Internally this
hollow body may be formed of any desired section, circular, square or otherwise.
Any required number of these sections to form the complete screw are then mounted
on a suitable hollow driving shaft-preferably steel-externally of a shape or section
similar to the internal section of the cylindrical body of the screw. The sections of
the screw may each be secured independently to the driving shaft by bolts, studs or
the like, or they may be formed with a locking joint. The trough and other parts
of the conveyor may be of any ordinary or suitable construction. The sections of
the screw may be coated with lead or a vitreous material to resist chemical action
where desired.
An advantage of the employment of this form of screw will be that considerable
less power will be required to drive it, and in case of breakage of any section of
the screw it could be replaced at small cost; in addition to which the initial cost
will be much less and it will be much stronger than those now in use.
Dated this 13th day of March 1895.
DAVID RUSHWORTH.

page_text: Improvements in Screw Conveyors.
I, DAVID RUSHWORTH, of 92 (late of 13) Manchester Old Road, Heaton
Chapel, near Stockport, in the County of Lancaster, Mechanical Engineer, do
hereby declare the nature of this invention and in what manner the same is to
be performed, to be particularly described and ascertained in and by the following
statement :-
This invention has reference to screw conveyors, and although primarily intended
for use in conjunction with mechanical stokers for feeding or supplying the coal or
other fuel to the hoppers, it may also with advantage he employed in collieries,
chemical and other works, and numerous other manufactures, for conveying or
transporting coal, minerals, ores or other solid or semi-solid materials or substances
or liquids from one fixed place to another as may be desired.
Hitherto the screws or worms of conveyors for these purposes have either been
constructed of a number of sections each of which sections has been of a length
equal to the pitch of the screw and comprised merely the thread or blade of the
screw in the form of thin spiral or helical strips threaded on to a solid central shaft,
or the whole screw has been cast solid in one continuous length. In the former
case amongst other objections the initial cost of production is high and the conveyor
is also necessarily considerably weakened, and in the latter case in the event of
breakage or fracture of any part of the screw it has necessitated the replacing of
the whole screw, in addition to which both forms owing to their weight have required
the expenditure of considerable power to drive them.
This invention is designed to obviate these objections.
It consists essentially in constructing the screw or worm of the conveyor of any
required number of sections, these sections being formed with a hollow core or
centre or with the thread formed on a hollow cylinder or cylindrical body and
being of a length equal to say, one, two, three or other like desired number of
pitches or convolutions of the screw, which sections will be keyed or otherwise
suitably attached preferably to a hollow driving shaft.
The invention will be fully described with reference to the accompanying drawings
in which
Fig. 1, shews a longitudinal part sectional elevation of a screw conveyor and
trough with my improved worm or screw applied thereto.
Fig. 2, a longitudinal elevation of a portion of the detached worm or screw with
one section drawn asunder shewing the locking joint I prefer to employ.
Fig. 3, a plan of the locking joint and
Fig. 4, an end elevation of the worm or screw and trough.
The trough A and the sprocket wheel B, or other driving mechanism, and the
parts of the conveyor other than the worm or screw C may be of any ordinary or
suitable construction.
The worm or screw C of the conveyor is built up or constructed of the required
number of sections to produce it to the desired length. These sections are cast or
otherwise formed with a hollow core c or with the thread or blade b formed on a
hollow cylinder or cylindrical body d which hollow core or cylinder may be of any
desired shape or section internally, circular, square or otherwise. Each section of
the screw may, as desired, be of a length equal to say one, two, three or other like
number of pitches or convolutions of the screw preferably two or three. The worm
as shewn in Fig. 1 is composed of six sections, three sections a a¹ a² being of a length
equal to one pitch or thereabouts, one section a³ being equal to two pitches and
the remaining two sections at being of a length equal to three pitches. These
sections of the worm are preferably made in cast iron as a great advantage accruing
from the use of this metal is that it to a large extent resists the corrosive and

page_text: other actions to which worms constructed of either steel or wrought iron are subject
when employed for conveying coal and the like. The sections to form the complete
screw are mounted or threaded on to a suitable driving shaft D-preferably hollow
- which externally is of a shape or section similar to the internal shape or section
of the hollow core or cylinder of the sections of the screw. In the drawings I
shew both the shaft and hollow core of the screw circular in cross section..
The driving shaft may without disadvantage be constructed of steel to obtain
great strength to resist the twisting stress to which it is subjected as it is entirely
covered and protected from the materials being conveyed by the sections of the
screw and therefore not liable to the corrosion or similar destructive action
previously referred to. Although 1 prefer to employ a hollow shaft, in some cases,
especially where screws of a small diameter are required, I may substitute a solid
one. In the construction of the driving shaft for long screws or worms it might
be made in sections and screwed together or otherwise connected to produce it to.
the required length. The sections of the screw or worm may each be secured
independently to the driving shaft by studs, cotters, bolts, or the like or the body
of the screw may be formed with a locking joint as shewn in the drawings or in any
other suitable and efficient manner and the extremities only secured to the shaft
or a separate piece as at E (Fig. 1) may be attached to the shaft to effect the same
purpose.
The sections of the worm or screw and the trough in which it rotates may be.
coated with lead, enamel or other vitreous material to resist chemical action where
desired.
Amongst the advantages of the employment of this form of screw or worm will
be that considérable less power will be required to drive it, and in case of breakage
of any section it could be replaced at small cost, in addition to which the initial
cost of production will be much less and it will be constructionally much stronger
than those now in use.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I wish it to be clearly
understood that I do not make a broad claim to a worm or screw built up of sections
but I declare that what I claim is :--
1. A worm or screw for screw conveyors constructed in sections, each section
being in the form of a length of a screw with a hollow core or centre or with the-
thread formed on a hollow cylinder or cylindrical body and of a length equal to
one, two, three or like number of pitches or convolutions of the screw mounted on
and attached to a driving shaft substantially as herein described and illustrated in.
the accompanying drawings.
2. A screw conveyor constructed with a sectional worm or screw each section
being formed with a hollow core or body and of a length equal to one, two, three-
or like number of pitches or convolutions of the screw attached to a driving shaft
substantially as herein described and illustrated in the drawings.
Dated this 11th day of December 1895.
DAVID RUSHWORTH.