Improved Process and Apparatus for Tanning Hides and Skins.
Year: 1890

page_text: Date of Application, 14th Nov., 1890
Complete Specification Left, 14th Aug., 1891-Accepted, 3rd Oct. 1891
PROVISIONAL SPECIFICATION.
Improved Process and Apparatus for Tanning Hides and Skins.
I, LORENTZ ALBERT GROTH, of 3 Tokenhouse Buildings, in the City of
London, Consulting Engineer, do hereby declare the nature of the said invention
to be as follows:-
This invention relates more especially to improvements in the process and
5 apparatus for tanning hides and skins by the aid of electricity but the said
improvements are also applicable to apparatus for tanning in which electricity is
not employed. One part of my invention consists of improved means for placing and
holding the hides or skins in, and for removing the same from the apparatus by which
the said hides or skins are kept in motion in the tanning liquor, and for this purpose
I employ in connection with the rotating or reciprocating frames or bars which carry
the hides or skins and keep them in motion in the tanning liquid, moveable frames
on one or both sides of which the hides or skins are stretched. These frames may
be easily removed from the rotating or reciprocating frames or bars for the
purpose of having the hides or skins removed therefrom when the tanning operation
is complete, and other fresh ones secured thereto ready for the next operation,
and they may be as easily replaced with the hides or skins on them in or on the
rotating or reciprocating frames or bars.
In tanning apparatus of the kind above referred to it frequently happens that the
tanning liquid does not exert an equal effect on all the hides or skins by reason of
their being suspended or stretched so near to each other that the tanning liquid
contained between them, is carried round along with, and remains stagnant
between the hides or skins instead of the latter being moved through such
liquid so as to secure a constant equable and continuous renewal of the liquid in
contact with the surfaces of the hides or skins.
liquid is also often carried round in the tan pit or vat by the hides or skins so that
The whole mass of tanning
both the liquid and the hides or skins rotate together in the same direction, the
practical effect being much the same as if both were stationary in the vat or tan
it, whereby the acceleration of the tanning operation, which would be effected
y the movement of the hides or skins in the liquid is more or less neutralized.
n order to prevent this stagnation of the tanning liquid between the hides or
kins, and the carrying round of the mass of liquid in the pit or vat, I so
gitate or circulate the liquid that it cannot, on the one hand, remain stagnant
etween the hides or skins, and on the other cannot partake of the rotary motion
f the hides or skins and of the frames or bars to which they may be suspended
r attached. For this purpose employ paddles or stirrers rotating in the
nning liquid and preferably mounted on shafts rotating in bearings on the rotary
ames or bars carrying the hides or skins, such paddles or stirrers with their shafts
ing caused to rotate independently of the rotary frames or bars by means of
itable gearing. These paddles or stirrers rotate in the liquid, and agitate it, and
event it from being carried round and round in a placid state, and occasion
ore or less circulation or movement of the liquid between the hides or skins.
According to another arrangement, I effect the circulation of the tanning liquid,
d prevent it more or less from being carried round with the hides or skins, by
ans of a rotary or other suitable pump, which draws liquid from the lower part
the vat or tan-pit and returns it into the upper part thereof, or vice versa.
According to another arrangement I effect the same object by placing two o1
re rotating frames or bars, each carrying its quota of hides or skins, in one
ionary vat or tan pit, the motion of each frame or bar counteracting and
[Price Rd 1

page_text: neutralizing more or less the tendency for the other or others to draw the liquid
round with it or them.
Circulation of the liquid, for the purpose of keeping it agitated or stirred, may
also be effected by storing the tanning liquid in an overhead tank, and allowing it to
run by gravitation from such tank into the vat or tan pit or through two or more
vats or tan pits in succession, after which it is pumped back into the overhead tank.
Dated this 14th day of November 1890.
LORENTZ ALBERT GROTH.
COMPLETE SPECIFICATION.
Improved Process and Apparatus for Tanning Hides and Skins.
I, LORENTZ ALBERT GROTH, of 3 Tokenhouse Buildings, in the City of
London, Consulting 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, reference being had to the accom-
panying sheet of drawings and to the letters and figures marked thereon:-
This invention relates more especially to improvements in the process and
apparatus for tanning hides and skins by the aid of electricity, but the said
improvements are also applicable to apparatus for tanning in which electricity is
not employed. One part of my invention consists of improved means for placing
and holding the hides or skins in, and for removing the same from the apparatus by
which the said hides or skins are kept in motion in the tanning liquor, and for this
purpose I employ apparatus such as is illustrated in Figures 1 & 2 of the drawings
hereto annexed.
Figure 1 is a vertical sectional elevation and Figure 2 a plan.
A is a stationary tank or vat provided with a cover or lid D and containing the
tanning solution. B B' are frames or bars connected to and rotating with a central
shaft E. The upper frames or bars B are arranged to carry on their outer arms
the moveable frames C on both sides of which the hides or skins Fare stretched
and the lower frames or bars B' serve as guides for the lower ends of the frames C.
The tops and bottoms of the frames C are made thicker than the sides, so that
when several of the frames are put together as shown, room is left between the
hides on
adjacent frames to allow the tanning solution to circulate between them.
The tops of the frames C are made longer than the width of the frames so that the
ends of the said tops may rest on the bars B. The frames C may be removed
from the bars B for the purpose of having the skins secured thereto and removed
therefrom.
Instead of a special stationary tank or vat A of circular shape, an ordinary tan-
pit may be used to receive the rotating frames, and it will be understood that the
shaft E and bars B. B, together with the moveable frames C and the hides or
skins F secured to the latter, are caused to rotate in the liquid contained in the
tank or vat A by means of bevil gearing G and counter-shaft H, or by other
suitable means, and that the rotary motion may be continuously in one direction or
alternately in opposite directions, and further that instead of rotary framing or
bars, as shown in Figures 1 and 2 for example, frames or bars on which the
hides or skins are hung or secured by means of moveable frames similar to
those shown at C, may be caused to reciprocate in a rectilinear or other direction
so as to move the hides or skins to and fro, or up and down, or to shake them,
in the tanning liquid.
Figure 24 is a longitudinal sectional elevation and Figure 28 a plan of the
apparatus arranged in this way, part of the cover D being removed.
A is the stationary tank, vat or tan pit. B B a cage or frame arranged to
reciprocate to and fro therein. C removeable frames similar to those above
described, and shown in Figures 1 and 2 having the hides attached thereto and
adapted so that the ends of their tops rest on the side frames B. B. The part of

page_text: the weight of the frames B B and C and of the hides secured to the latter, that is
not balanced by displacement of the tanning solution in the tank, vat or tan pit A
is carried by the friction rollers Y which turn on pins secured to the side
frames B B. The rollers Y rest on guide rails Z placed on the sides of the tank,
vat or pit A, the said rails thus acting as guides for the motion of the frames B B
and C.
Horizontal or vertical reciprocating or shaking motion may be imparted to the
frames B B and C by any suitable means such as a crank and connecting rod for
example as shown by dotted lines in the figures.
The frames or bars B B as well as the moveable frames C, are preferably made
of timber, but other suitable material, which will not act injuriously on the tanning
materials may be employed.
-
+ and
are electrodes connected with a suitable source of electricity for the
purpose of passing a current of electricity through the tanning liquid in the
stationary tank, vat or ordinary tan pit A. These electrodes are preferably fixed
at the sides of the tank, one opposite the other and covering a small surface only.
In the case of the apparatus shown in Figures 1 and 2, one of the poles,
preferably the negative one, may take the form of a cylinder and be fixed in the
centre of the revolving frames round the shaft E for example whereby the distance
the current has to traverse is. materially reduced as compared with the distance
it has to traverse when the positive pole is placed at one side of the tank and
the negative pole at the other side as shown in the figures.
In some cases
I have found it advantageous to cause the electrodes to rotate or reciprocate in
the tank instead of being fixed, suitable means being provided for maintaining
their connection with the source of electricity. The size of the electrodes and
the strength of the current are entirely dependent upon the nature and quality
of the hides or skins as well as upon the nature of the tanning liquid and cannot
therefore here be exactly specified for each particular case, but it may be
mentioned that a weak current is generally speaking better than a strong one.
The apparatus is employed as follows:
-
A number of hides or skins are mounted on the frames C secured to the
rotating or reciprocating frames or bars B B'. Ordinary tanning liquor only is
then admitted to the tank A until the hides or skins are immersed in such
liquor. The frames or bars and consequently the hides or skins, are set in
motion, and the electrodes + and are connected to the source of electricity so
that a current of electricity is passed through the liquid and hides. The motion
of the frames or bars and of the hides or skins is continued for from one to thirty
days more or less according to circumstances, the current of electricity being
maintained during that time, or during a part thereof only according to circum-
stances, and as may be necessary for the materials under treatment; at the end
of that period the tanning of the hides or skins will be completed; the motion
of the apparatus is then arrested, the current of electricity stopped, if it has not
been previously stopped, the tanning liquor drawn off from the tank A and the
tanned hides or skins removed. Fresh hides or skins are then put in and the
cycle of operations repeated, and so on continuously.
In my above described apparatus for tanning hides and skins, it frequently
happens that the tanning liquid does not exert an equal effect on all the hides
or skins, by reason of their being suspended or stretched so near to each other
that the tanning liquid contained between them, is carried round along with, and
remains stagnant between the hides or skins, instead of the latter being moved
through such liquid, so as to secure a constant equable and continuous renewal
of the liquid in contact with the surfaces of the hides or skins. The whole
mass of tanning liquid is also often carried round in the tan pit or vat by the
hides or skins, and by the frames on which they are hung, so that both the
liquid and the skins rotate together in the same direction, the practical effect being
much the same as if both were stationary in the vat or tan pit, whereby the
acceleration of the tanning operation, which would be effected by the movement

page_text: of the hides or skins in the liquid, is more or less neutralized. In order to
prevent this stagnation of the tanning liquid between the skins, and the carrying
round of the mass of liquid in the pit or vat, I so agitate or circulate the liquid
that it cannot, on the one hand, remain staguant between the skins, and on the
other, cannot partake of the rotating motion of the hides or skins and of the frames
to which they may be suspended or attached. For this purpose I employ the
modifications shown in Figures 3 to 8 of the drawings, in which Figures 3, 5 and 7
are vertical sectional elevations showing the apparatus applied in a tanning tank,
vat or pit;
Figures 4 and 6 plans corresponding respectively to the sectional elevations
shown in Figures 3 and 5, and Figure 8 a plan of a pit showing several of the
apparatuses above described placed therein so as to produce an agitating or
circulating effect in the liquid by their respective rotary motions.
Referring to Figures 3 and 4, A is the stationary vat or ordinary tan pit
containing the tanning liquid, E the vertical shaft arranged to rotate in the
centre of the said vat or tan pit, B B the frames or bars secured on the shaft E
and carrying the moveable frames C on which the hides or skins F are stretched,
all these parts being arranged in a manner similar to that shown in Figures 1 and 2.
The shaft E and frames or bars B. B', together with the moveable frames C
and the hides or skins F, are caused to rotate say in the direction of the arrow
(Figure 4) in the liquid contained in the stationary vat or tan pit A by means
of bevil gearing G and counter-shaft H, or otherwise. And it will be readily
understood that the rotation of those parts in the liquid will tend to impart a
rotary movement also to the said liquid. In order to neutralize the effect of the
rotary motion thus imparted to the liquid, I employ rotary paddles or stirrers I
mounted in bearings at each corner of the frames B B'. These paddles or stirrers
are caused to rotate at a much greater speed than the main shaft E by means of a
spur wheel J secured to the cover D of the vat or tan pit A or otherwise fixed
so that it cannot rotate. Spur pinions I mounted on the shafts I of the paddles
or stirrers gear with the spur wheel J. As the frames B B rotate, they carry
with them the paddles or stirrers I, their shafts I and pinions K. The latter
are thus carried round the fixed spur wheel J, but being geared therewith are
caused to rotate in the direction of the feathered arrows carrying with them their
shafts and paddles or stirrers I. The latter act upon the liquid, agitate it, and
prevent it from being carried round and round it in a placid state; and occasion
more or less circulation or movement of the liquid between the hides or skins F.
Another modification for securing circulation of the liquid and preventing it,
more or less, from being carried round in the stationary vat or tan pit, is also shown
in the same Figures 3 and 4, and may be employed alone, or in combination with
the rotary paddle arrangement above described. It consists of a rotary or other
suitable pump L, which draws liquid by the suction pipe M from the lower part
of the vat or tan pit A. and returns it by the delivery pipe N into the upper part
of the vat or tan pit; such liquid being preferably introduced thereinto at N' in a
tangential direction opposite to that of the motion of the frames or bars B B. By
these means, the whole of the liquid is kept circulating from above downwards so as
to prevent stagnation in any part of the vat or tan pit, and the introduction at N¹
in a direction opposite to the motion of the hides or skins prevents more or less
the general rotary movement of the liquid. It is obvious that, if preferred, the
pump may be arranged so as to produce circulation of the liquid from below
upwards,
Figures 5 and 6 show another modification for stirring or agitating the liquid in
the centre of the vat or tan pit, which liquid is liable, in the arrangement shown in
Figures 3 and 4, to remain more or less stationary. E is the vertical shaft as
before, carrying the frames or bars B B¹. I is a hollow shaft or sleeve threaded
over the shaft E and free to rotate thereon. I are paddles or stirrers secured to
the shaft I. K is a spur wheel secured to the upper end of the shaft 11. K' is a
spur wheel gearing with the spur wheel K and secured to the lower end of the vertical

page_text: counter-shaft P turning in bearings in a bracket Q fixed to the upper frame or
bars B. R is a pinion secured on the upper end of the counter shaft P and gearing
with the internal spur wheel J secured to the cover D, or otherwise fixed so that it
cannot turn.
When the frames or bars B B are turned in the direction of the arrow in
Figure 6, the pinion R is caused to travel round the internal spur wheel J, thereby
turning the shaft P and spur wheel K¹ which, in its turn, rotates the spur wheel K
and with it the shaft and paddles or stirrers I in the direction of the feathered
arrow, that is to say in the same direction as the frames or bars B B', but at a
greater speed, whereby the liquid in the centre of the stationary vat or tan pit is
thoroughly agitated and driven outwards towards the circumference thereof.
The same figures show a modification of the means shown in Figures 3 and 4
for securing circulation of the liquid from top to bottom of the vat or tan pit.
L shows the rotary pump as before, M the suction pipe and N the delivery pipe;
but instead of the liquid being delivered tangentially, it is delivered through a
perforated or sparge pipe N2 at the end of the delivery pipe N, so that it falls back
into the vat or tan pit in the form of rain over the upper ends of the hides or skins
as they pass under the sparge pipe.
Figure 7 shows a modified arrangement for securing circulation of the liquid in
the vat or ordinary tan pit. In this case the shaft E is made hollow so as to serve
as the barrel of a pump. It is provided near its lower end with holes S to admit
liquid. T is a suction valve. U is the pump piston or bucket provided with a valve
opening upwards in the usual way. Vis the pump rod actuated by an eccentric W
on the countershaft H. X are pipe branches radiating from the upper part of the
shaft E towards the circumference of the vat or tan pit. The upper end of the
pump barrel or shaft E is open and the boss of the driving bevil wheel El surrounds
it so that free play is left for the lateral movements of the pump rod V.
As the shaft E revolves, the pump bucket U is moved up and down therein by
its eccentric W, being prevented from turning therewith by the joint of the pump
rod V; liquid is thereby drawn from the lower part of the vat or tan pit through
the holes S and valve T and delivered by the bucket U to the branch pipes X
which return it to any part of the vat or tan pit that may be desired. Instead of
pump
barrel being formed of the shaft E, the latter may simply be made hollow,
as shown, with openings S in its lower part, and an ordinary pump barrel, or the
suction pipe of pump, be inserted therein, so secured that it remains stationary
when the shaft E rotates.
the
Figure 8 shows an arrangement in which several rotating frames, each carrying
its quota of hides or skins, are placed in one stationary vat or tan pit, the motion of
each frame counteracting and neutralizing more or less the tendency for the other
or others to draw the liquid round with it or them.
Circulation of the liquid, for the purpose of keeping it agitated or stirred, may
also be applied by storing the tanning liquid in an overhead tank and allowing it to
run by gravitation from such tank into the vat or tan pit or through two or more
vats or tan pits in succession, after which it is pumped back into the overhead
tank.
It is obvious that if necessary the tanning liquor contained in the tank, vat or
pit, in which the hides are caused to reciprocate or to be shaken, may be agitated
or circulated by suitable modifications of the appliances above described in order
to prevent stagnation of the tanning liquor in the spaces between the hides, though
such agitation or circulation is not so necessary in the case of the reciprocating
arrangement as in that of the rotary.
Similar letters of reference relate to like parts in all the figures of the drawings.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I would have it understood
that I do not claim broadly the use of electricity in tanning, or apparatus for

page_text: keeping the hides or skins in motion in the tanning liquid, but I declare that what
I do claim is :-
First. The method or process of tanning which consists in keeping the hides or
skins in motion in a stationary or fixed tank, vat, or ordinary tan pit containing
the tanning liquor, in keeping the tanning liquor in motion so as to prevent the
same from becoming stagnant between the hides or skins and from being carried
round therewith, and in passing a current of electricity, or not, through the tanning
liquor and the hides or skins substantially as hereinbefore described.
Second. In apparatus for tanning hides or skins in which such hides or skins
are kept in motion in a stationary or fixed tank, vat, or tan pit containing the
tanning liquor, the combination with the main rotary reciprocating or other frame-
work B B of the separate removable frames C for carrying the hides or skins,
substantially as hereinbefore described and illustrated in Figures 1. 2. 24 2B 3 and 4
of the drawings.
Third. In apparatus for tanning hides or skins in which such hides or skins are
kept in motion in a stationary or fixed tank, vat or tan pit containing the tanning
liquor, the combination with the apparatus for keeping the hides or skins in motion
of means or apparatus for stirring, agitating, or circulating the said tanning liquor
in the said tank, vat or tan pit, substantially as hereinbefore described, and
illustrated in Figures 3 to 8 of the drawings and for the purposes specified.
Dated this 14th day of August 1891.
LORENTZ ALBERT GROTH:
W. H. Beck,
115, Cannon Street, London, E.C., Consulting Engineer and Patent Agent.