Improvements in Apparatus for Exposing Tea, Coffee, Cocoa, Grain, and other Substances to the Drying or other Action of Air, Vapor, or Gases.
Year: 1894

page_text: Date of Application, 19th Nov., 189+-Accepted, 23rd Mar., 1895
COMPLETE SPECIFICATION.
Improvements in Apparatus for Exposing Tea, Coffee, Cocoa, Grain,
and other Substances to the Drying or other Action of Air,
Vapor, or Gases.
I, SAMUEL CLELAND DAVIDSON of Sirocco Engineering Works, Belfast,
Ireland, Merchant, 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 :-
The invention has reference more particularly to the apparatus described in the
Specification of previous Letters Patent granted to me, and dated 2nd February 1892,
No. 2046 (which Specification, for brevity of description, is hereinafter referred to
as the previous Specification) but it is also applicable to any other apparatus using
tilting trays on endless bands or chains, the edges of which tilting trays overlap one
another when the trays are horizontally in line, so as to form a continuous web upon
which the material is carried, for drying or other purposes; and one object of the
hereinafter described improvements is to more efficiently effect the reversal of the
overlap of the edges of said trays, than as described in the previous Specification,
or as hitherto effected, in their passage from the top surface of an endless web
formed by them to the lower surface of same, and vice versa, which reversal of
overlap is necessary (as is set forth in the previous Specification) in order that the
trays may tilt free of one another, so as to drop the material at the end of both the
upper and lower stretches of said endless webs, and another object of the hereinafter
described improvements is to effect a more even distribution of the material when
discharged by the trays on to the surface of the endless webs below, which receive
same.
The method described in the previous Specification for effecting the reversal of
the overlap of the trays when passing round the sprocket wheels on which the
endless webs are mounted, has since been found in practical working occasionally
liable to derangement, from strings or other obstacles getting in with the material
to be dried, and becoming entangled with or otherwise preventing the trays at the
place where they swing down and effect their change of overlap by side guides and
gravitation, from properly accomplishing the passing of their edges from the correct
overlap for the top surface to that for the lower one; but by the hereinafter
described improvements this reversal is effected by the positive action upon the
trays of specially-shaped projecting ledges or rims on the sprocket wheels round
which the endless chains of the trays pass (or on a separate wheel on the same
spindle) which engage the end holders of the trays or the trays themselves and
absolutely compel the trays before descending to the under stretch of the endless
web, or ascending back again to the upper stretch, to reverse the overlap of their
edges, without dependence on any gravitating or swinging motion of the trays
themselves, such as described in the previous Specification. It is obvious, without
further description, that if the projecting ledges, rims or arms which effect the
reversal of the overlap of the edges of the trays, after dropping their contents and
before passing round the sprocket wheel, be applied on a separate wheel keyed on
the sprocket wheel shaft, the same results will be accomplished thereby as when
they are attached to the sprocket wheel itself, as herein before described, but as the
latter arrangement is a more convenient method of applying them, it is the one
which is preferably employed, and which is illustrated in the accompanying
drawings.

page_text: The hereinafter described improvements. for effecting the more even distribution
of the material when discharged by the trays upon the surface of the endless webs
immediately below same, consist in giving the trays two or more drops, the first of
which is so regulated by the position of the stop or bar against which the tray falls
(and which is preferably adjustable) that the tray can only drop to such an angle
that the material upon it is thereby only partially discharged to the surface below,
after which, the tray on being drawn forward clear of this stop or bar, again falls
against another stop or bar which is so placed that the tray drops to a vertical
position before striking it, and thereby discharges the remainder of its load of
material. Should it be desired, however, to still further spread the material, by
means of three drops instead of two, there may be another drop interposed between
the two above-described, in which the stop or har against which the tray falls
is so placed that the tray drops to such an angle that a further portion only of
the contents left upon it after the first drop is thereby discharged.
Reference to the accompanying drawings will more fully explain the nature of
the invention. The apparatus, as hereinafter described, and represented in same, is
more particularly intended for drying purposes, but with suitable modifications
may also be employed for other purposes for which substances are exposed to the
action of air, vapor or gases.
Figure 1 is a vertical section of the apparatus on the line A B of Figure 4.
Figure 2 is a transverse section on the line C D of Figure 1.
Figure 3 is a transverse section on the line E F of Figure 1.
Figure 4 is a horizontal section on the line G H of Figure 1.
Figures 5 and 5 are respectively an elevation and a section of the sprocket
wheel e².
Figures 6 and 6 are respectively an elevation and a section of the sprocket
wheel e.
Figure 7 is a view of the driving pulley showing the spring safety clutch, to
prevent the machine being accidentally driven in a reverse direction.
Figures 5, 5, 6, 6 and 7 are on a larger scale than Figures 1 to 4.
a a are the transverse flat trays attached at their ends by holders bb, which
are pivoted on endless chains er, the pivots being so placed in an intermediate
position between the leading edge of the trays and the centre that they will
drop into a vertical position when unsupported. The holders bb and endless
chains ce travel along and are supported by rails or bars d d and the chains
pass round and are returned by the sprocket wheel e at the driving end, and e³
at the opposite end. The sprocket wheels at one end of the machine may be driven
by any suitable means; the arrangement shewn is a combination of worm and
bevel gear.
At the point the upper rails are so discontinued that they no
longer support the ends of the trays, and therefore allow the trays to drop, and
at the point g the lower rails are discontinued, with the same object.
On reference to the figures, it will be seen that the leading edge of each tray
in the horizontal stretches of the endless webs, overlaps the trailing or rear edge
of the preceding tray, and that each tray is free to drop on its pivots when the
support of the rails d d ceases at for g on the upper or lower stretches
respectively.
Each tray on passing the point f drops downwards from the horizontal position
and strikes against the stop h, which is capable of being so adjusted that the tray
on striking it only drops to a sufficient angle to partially discharge its load of
material upon the trays below. The stop is carried upon a spindle I, and is
regulated by a handle 12 outside the machine, and which is held in position by a
pinching screw or pins in the quadrant 1', and the range of its adjustment is such
that the tray may be allowed to drop to any required angle between the horizontal
and vertical, as different materials, and also the same material in its different
degrees of dampness, in passing through the machine, require different adjustments
of the angle for this partial discharge; and in order to set the adjustable stops
correctly, a glass door is provided, preferably in the side of the machine, so that

page_text: the discharge may be observed while the machine is working. After the tray has
passed over the stop h, it drops (in the arrangement illustrated) to a vertical
position against the stop 2, with sufficient force to shake off the remainder of the
material. By thus only partially discharging the contents of the trays at the first
drop, the material is more equally distributed over the trays below than if it were
all dropped at one time, and the remainder of the material which is discharged at
the second drop of the tray falls on a hinged flap or apron ³ attached to the
stop 2, off which it slides down upon the under or returning trays of the endless
webs, and thus further assists the even spreading of the material thereon. The
tray after travelling clear of the stop h³, then strikes against the stop ', which is
attached to and moves with the movable bearing of the sprocket wheel e², so that
as the said sprocket wheel is moved forward or backward by the adjusting
screws (Figure 4) to tighten or slacken the chains carrying the trays, the stop /*
always maintains the same relative position thereto, and guides the trays correctly
on to the projecting rims or ledges m of the sprocket wheel e², and the further
revolution of the wheel then causes these projecting rims, owing to their special
shape (as illustrated in the accompanying drawings) to tilt the trailing edge of
each tray above the line of the top horizontal stretch of trays, as shown at 8 in
Figure 1, and thereby reverse the overlap of the edge of the tray from what is
was in the said top horizontal stretch or web, and the trays are then carried round
with the sprocket wheel in this same relative position to one another, until the
chain on leaving the wheel, draws the trays forward over the guide j on to the
rails & into the horizontal stretch of trays which forms the under or returning web,
with the overlap of the leading edge of each tray on top of the trailing edge of
the tray in front of it.
Then at the opposite end of the under web before the trays ascend back to the
top stretch of the endless web, the trailing end of each successive tray on
reaching the point drops against the adjustable stop k, but only to a
sufficient angle to partially discharge its contents, as already described in
respect of the trays of the top web, and after travelling clear of stop k, it
then drops into a vertical position against the stop 2 and discharges the
remainder of its contents over the apron ³, after which the chain draws the
tray again into a horizontal position over the horizontal supporting ledge of
the stop 2, the length of which must be such that the pivot of the tray
should have just cleared its rear end as the tray following reaches its front
end, whereupon the nose or point n of the projecting ledges n² of the sprocket
wheel bears down on the leading end of the tray or its end holders, and
presses it down past the rear end of the stop k², and thereby tilts the trailing
end of the tray up clear of the leading end of the tray following, into the
position shown at q in Figure 1, which reverses the overlap of their edges, and
the trays are then held in this same relative position to one another by the
projecting ledges n² while passing round the sprocket wheel, so that when drawn
by the chain on to the top rails d, the overlap of the leading end of the tray
is on top of the trailing end of the tray preceding it.
In the lower or returning stretch of trays in the lowest of the endless webs, the
dropping tray discharges its entire load of material by one single drop into the
discharge shoot o, whence it is delivered out of the machine by the discharging
wheel, which is constructed in compartments, as shown in Figure 1 to prevent
the passage of any current of air either into or out of the machine, according to
whether it is being worked by means of a partial vacuum or pressure of air in the
compartment below the trays. In the drying apparatus herein illustrated, the hot
air is introduced at the top of the machine, and the exhaust air drawn away from
below, by an exhaust fan, but when preferred the heated air may be introduced
under pressure below the trays, or drawn up through them by an exhaust fan
operating from above them.
The feed inlet to the machine, for the material to be dried, may be fitted with
any suitable feeding or spreading apparatus for supplying the upper endless band

page_text: with a regular quantity of such material. The means shown consist of an endless
band of flat laths & carried upon chains running on sprocket wheels s² one of which
may be driven by means of a chain (Figure 3) from the spindle of the upper
endless band. The thickness of the material fed into the machine is indicated by
the inlet door u, which may be raised or lowered by means of the worm gear u³;
pp are doors for examining the various parts of the interior of the machine; q is
the hot air supply duct, and the opening to the exhaust fan.
In case the machine were by mistake started with the driving pulley rotating in
the wrong direction, some damage to the trays might ensue. To render this
impossible, the driving pulley is fitted with a clutch illustrated in Figure 7, in
which is the driving pulley running loose on the shaft v; to is a clutch keyed on
the shaft 2 but free to slide in and out of gear, and kept in gear with the driving
pulley by the spring . It is obvious that the clutch can only drive the machine
in one direction, and that if the driving pulley be rotated in the opposite direction
to that in which the clutch is intended to operate, it comes out of gear, by
compressing the spring back along the driving shaft; y is the shaft bearing.
The herein before described method of reversing the overlap of the edges of the
trays in passing round the sprocket wheels from the upper to the lower surface of
the endless webs, and vice versa, is so certain and positive in its action that no
obstruction of any ordinary nature can prevent the operation taking place, nor does
a high speed of drive, nor any sudden variations in the speed affect its efficiency,
hence the invention will prove of public utility.
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 machines for exposing tea, coffee, cocoa, grain and other substances to the
drying or other action of air, vapor or gases, upon each horizontal stretch or surface
of endless webs consisting of a series of oblong perforated plates or trays, pivoted
between conveying chains carried on sprocket wheels at either end, and with their
edges so overlapped that each of the trays has its trailing edge underneath the
leading edge of the tray following, in order that it may drop freely to discharge
its contents on reaching the end of each horizontal stretch, in a manner similar to
that described in the previous Specification, the employment either upon said
sprocket wheels or upon separate wheels keyed upon the sprocket wheel shafts, of
projecting ledges, arms or other equivalent devices, which in revolving with the
sprocket wheel, so engage each successive tray, or any suitable attachment thereon,
after it has discharged its contents and before it is led round the sprocket wheel,
that its trailing edge is thereby projected above the leading edge of the tray
following and retained in that position while passing round with the sprocket wheel,
whereby when the conveying chain carries it therefrom to the next horizontal
stretch or surface of the endless web, the trailing edge is again underneath the
leading edge of the tray following, all substantially as hereinbefore described and
represented in the accompanying drawings.
2. In machines for exposing tea, coffee, cocoa, grain and other substances to the
drying or other action of air, vapor or gases, upon each horizontal stretch or surface
of endless webs, as referred to in Claim 1, the employment of an arrangement
whereby the trays, for the purpose of discharging their material at the end of each
horizontal stretch, may receive two or more drops from the horizontal position, in
the first of which drops the tray can only fall to such an angle that the material
on it is thereby only partially discharged to the surface of the web below it, and in
the last drop, to such an angle that the remainder of the material is entirely
discharged, all substantially as and for the purposes herein before described and
represented in the accompanying drawings.
3. The regulation of the angle to which the trays drop in discharging their
contents upon the lower end of each stretch or web, as referred to in Claim 2, by
the employment of adjustable stops or bars against which the trays strike, so tha

page_text: the quantity of the material that the tray will discharge at each drop, may be
regulated as required, all substantially as and for the purposes herein before described
and represented in the accompanying drawings.
4. The combination of parts forming the improved apparatus for exposing tea,
coffee, cocoa, grain or other substances to the drying or other action of air, vapor,
or gases, all substantially as hereinbefore described and represented in the
accompanying drawings.
Dated this 16th day of November 1894.
J. C. MEWBURN & ELLIS,
55 and 56, Chancery Lane, London, Patent Agents.