A Machine for Sifting and Sorting Tea or similar Substances.
Year: 1888

page_text: Date of Application, 12th Oct., 1888
Complete Specification Left. 11th July. 1889-Accepted. 5th Oct.. 1889
PROVISIONAL SPECIFICATION.
[Communicated from abroad by J. E. LYNDALL, of Sylhet, India, Engineer.]
A Machine for Sifting and Sorting Tea or similar Substances.
I DANIEL SMITH SINCLAIR of 54 Gordon Street Glasgow in the County of Lanark
Engineer do hereby declare the nature of this invention to be as follows:-
An upright shaft having its ends supported by two cranks which are so connected
as to run synchronously together. The shaft is carried round parallel to itself in a
circular orbit of the radius of the cranks and at the same time revolves about its
axis; the latter motion being derived from the shaft which drives the cranks. This
motion may be in the same sense or in the opposite sense to that in which the
cranks move.
The shaft first referred to carries one or more sieves which are so arranged as
to be movable up and down on the shaft whilst the machine is in motion with
the object of bringing their top surfaces clear of the rim and they may be so
connected as to bave their up and down movement-simultaneously or they may be
independent in this respect.
Concentric with each sieve and rim is an annular trough which preferably does not
revolve. Into this the particles too large to pass the mesh of the sieve will fall when
the sieve is brought clear of the rim, the machine being in motion. The trough may
receive a jigging motion to facilitate the passage of the tea (or other substance) to
a shoot at its lowest point.
When more than one sieve is in use the particles passing through one are guided
by a conical shoot to the next which will generally have a finer mesh. On this
sieve and the successive ones, if used, the same operations take place as on the
first. The particles passing through all the sieves are disposed of in any convenient
manner.
A 'plowboard' of suitable size & shape may be fastened to any convenient
part of the machine and held inside the revolving sieve in such a manner and at
such a point as may be most effective in turning over and dispersing the substance
being sieved.
D
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COMPLETE SPECIFICATION.
A Machine for Sifting and Sorting Tea or similar Substances.
I. DANIEL SMITH SINCLAIR of 54 Gordon Street Glasgow in the County of Lanark
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 relates to improvements in machines for sifting and sorting Tea.
In machines of this class it has been usual to give the sieves a reciprocating motion
on account of the difficulty of producing good results with a machine in which
the sieves have a rotary or rotating motion but in the machine herein described
these difficulties have been overcome and a labour-saving appliance has been produced
with the mechanical advantages of a circular motion and capable of a large out
turn of well sifted Tea & occupying less floor space in proportion to work done
than do machines heretofore in use.
In order to better understand how I carry this Invention into practice I have
prepared the annexed drawing which shows a machine in which 3 circular sieves
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page_text: of different meshes are superposed on a common axis as will be usual in larger
machines so as to sift and deliver tea in four grades at one operation.
Each set, consisting of a sieve & its accessories is similar to the other in every
respect & machines may have one or any greater number arranged one above another
as shown.
I shall first describe the sieve & its adjuncts. The sieves rims and
troughs are all circular & the rims are fixed to and supported by narrow brackets (28)
at each spoke of the frame (5). In the figure the top sieve is shown in section
and the two lower ones in. elevation but the same figures of reference apply to all.
To each sieve there are three main parts; a sieve (I) a rim (2) fitting close to it
and an annular trough (3). Each of these is supported independently on the
frames (4) (5) & (6) respectively which are carried by a central shaft (7) and an
outer tube (8) the latter being so arranged as to be capable of sliding a short
distance up & down on the central shaft. Of the three frames (4) and (6) are
fixed to the central shaft being fastened by screws passing through slots in the
tube & biting on the shaft. The other frames (5) though driven by the shaft
are supported by the tube so that they may be raised & lowered relatively to (4)
& (6). The effect of so doing when the machine is in motion will be to allow
the tea to be discharged by tangential inertia from the surfaces of the sieves (1)
and to pass into the troughs (3).
When the machine is made with only one sieve it will be sufficient to support
it on one crank such as the lower of the two shown in the figure and in this case
the discharging gear will be fixed to this crank but if there are more than one
sieve it will be necessary to support the top end of the shaft & for this purpose
the top crank (10) must be connected to the lower one (26) by the shafting (17)
& four pairs of bevil gearing wheels or other well known method. The first shaft
may itself be driven by a belt conveniently arranged or by hand power.
The shaft 18 has keyed to it the crank (26) at the outer end of which is a
bracket (23) carrying a roller (24) running on a circular railway (25). This is
to take the weight of the shaft (7) the sieve etc. off the crank & bearings of the
driving gear The crank carries three wheels in gear but the intermediate one may
be dispensed with. The wheel (19) is fixed to the bracket (20) and does not
revolve and in general I prefer to have this wheel larger than the last follower (22).
The effect of having these wheels (19) & (22) of different sizes is to make the
shaft (7) rotate about its axis and it carries the frames (4) & (5) and their attach-
ments with it. The sieves have thus two distinct motions, a circular orbital
movement about the axis of the shafts (11) & (18) and a rotation about the axis
of shaft (7).
The intermediate wheel on the crank (26) changes the direction of the latter
inotion, and the relative sizes of the wheels (19 & 22) can also be easily changed so
that by suitably choosing these an approximation to the motion given to a hand sieve
or riddle can be obtained. A very good sifting motion is produced by making (19)
of twice the diameter of (22) & introducing an intermediate wheel between the two.
The orbital & rotational movements are thus in opposite senses and the tea is
continuously spread over the surface of the sieve.
To aid in this spreading another device which I call a a plowboard' is introduced
in this machine. To the edge of the trough (3) is attached a bracket (14) prefer
ably of metal carrying a board (15) which at two of its edges is close to the sieve &
to the rim. If now, as the construction admits and as is intended to be done the
trough is prevented from revolving with the shaft (7), and a heap of tea is carried
against the board it will be scattered & spread over the surface of the sieve. In
order to accomplish this the better the lower edge of the board is further advanced
than the top so as to present an inclined plane for the tea to be forced up. The
board is not placed radially on the sieve but pointing backwards in the direction: of
motion so as to throw the tea towards the centre.
The lever (12) is forked at the end & engages in trunnions on a washer that
encircles the top of the shaft (11). Another washer is fixed above to the shaft so-

page_text: that the latter may be lifted on moving the lever. The shaft has a groove
cut in it longitudinally and a feather on the bevil wheel through which it passes
engages in the groove. The shaft is thus driven by the wheel but it can be inde-
pendently moved vertically by pulling on the free end of the lever. The crank (10)
is keyed to the shaft (11) but the sieve shaft is free to rotate and a collar (9) is
fixed on the tube shaft (8). It will be seen that the pulling down of the lever-
end will raise the shaft (11) the crank (10) the tube shaft (8) and with the latter
the frames (5) which carry the sieve rims and when this is done the tea by the
motion of the sieve will be jerked into the trough (3).
In automatically discharging the tea from the troughs they are provided with a
a spout or shoot which has a flexible tube attached to allow of the orbital motion of
the sieve etc. being performed and the other end being fixed pours the tea into a
suitable receptacle. I also make the troughs in halves & hinged so as to fall down
and then the tea from each half may be emptied into a tray, when the machine is
stopped.
The dotted lines (27) are the centre lines of light straps tying the frames together
to render the machine more rigid.
(29) are conical shoots attached to the frames (5) to direct the falling tea into the
next lower sieve.
my said
Having now particularly described and ascertained the nature of
invention and in what manner the same is to be performed I declare that what I
claim is :-
1. A machine for sifting tea or similar substances with one or more sieves substan-
tially as & for the purpose described.
2. A machine for sifting tea having such motions accomplished by such means as
are herein set forth.
3. The application to machines for sifting tea of such sifting motions as are herein
described.
4. In a machine for sifting tea the circular trough as & for the purpose described.
5. In a machine for sifting tea a construction and arrangement of parts whereby
the tea can be discharged from the top of the sieve by lowering the sieve or by
raising the rim substantially in the method described.
6. In a machine for sifting tea the contrivance called a 'plowboard' substantially as
described though not necessarily attached to the trough as shown.
Dated this 9th day of July 1889
D. S. SINCLAIR.
Applicant.