Ores, Grain, or other Produce or Materials.
Year: 1888

page_text: Date of Application, 24th Apr., 1888
Specification Accepted, 8th June, 1888
Ores, Grain, or other Produce or Materials.
I FRIEDRICH OTTO LINDHEIMER Architect of Frankfurt a/m in the Kingdom of
Prussia and German Empire 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 :-
According to this Invention a suitable number of grinding blocks or prisms having
suitable ridges and furrows provided on their sides are connected at their ends in such
a manner as to form two horizontal frames or gratings so that the blocks.of one
frame are arranged alternately with the blocks of the other frame.
An alternating forward and backward or reciprocating motion being imparted to
one or both frames in the direction of the length of the grinding blocks by means of
an eccentric or crank and the frames being supported upon wheels or quadrants to
facilitate this movement the materials or substances to be reduced are crushed, ground
or comminuted as they pass downwards between the blocks.
According to the dimensions of the mill and according to the wider or closer
adjustment of the grinding blocks and the nature of the ridges and furrows materials
or substances of all descriptions requiring reduction to small pieces or particles such
as ores or other minerals chemicals roots grain pulse malt sugar and the like can be
crushed broken triturated comminuted or ground to any desired extent or degree of
fineness in a superior and effectual manner.
The grinding blocks may be either fixed relatively to one another that is to say,
without means for setting the acting surfaces closer together or wider apart or they
may be provided with mechanism for adjusting or regulating the distances between
them. One of the frames may be stationary and the other partaking of a reciprocating
motion or both of the frames may be moveable or reciprocating
The accompanying drawings illustrate the three arrangements, namely.
(a.) A machine with adjustable grinding blocks and one reciprocating frame.
(b.). A machine with fixed grinding blocks, that is to say, without means for
adjusting the acting surfaces and with one moveable or reciprocating frame.

page_text: (c.) A machine with adjustable grinding blocks, both frames pártaking' of a
reciprocating motion.
(a.) Figures I to X of the accompanying drawings illustrate a machine with
adjustable grinding blocks, one of the frames being moveable and the other fixed. The
movements of the frame are produced by a lever which is moved forwards and
backwards by an eccentric. In these figures:
Figure I represents a longitudinal section of the front part.
Figure 11 represents a transverse section, taken along the line A B, Figure I.
Figure III is a longitudinal section through the hinder part.
Figure IV is a front elevation.
Figure V is a side elevation of the front part.
Figure V1 is a side elevation of the hinder part.
Figure VII is a horizontal section of the front part of the cover of the mill being
removed.
Figure VIII is a plan of the hinder part.
Figure IX illustrates the adjusting mechanism for the grinding blocks in plan.
Figure X represents the grinding blocks in section.
(b) Figures XI to XIII illustrate a machine without regulating mechanism and in
which one frame is fixed whilst the other has an alternate forward and backward
motion imparted to it by means of a lever. In this machine a multiple arrangement
of the grinding blocks is provided there being several series of grinding blocks
arranged one above the other. In these figures-
Figure XI is a longitudinal section through the front part.
Figure XII is a partial transverse section along the line 1-2 Figure XI.
Figure XIII is a front, elevation of one half of the machine.
(c) Figures XIV to XX illustrate a machine with adjusting arrangement for the
blocks and in which both the frames are capable of moving forwards and backwards
receiving motion from a cranked shaft operated by a crank or pulley. In these
figures
Figure XIV is a longitudinal section through the front part.
Figure XV is a front view of the front part.
Figure XVI is a plan of the front part with the adjusting mechanism removed to
avoid complication.
Figure XVII illustrates the crank shaft.
Figure XVIII is a plan of the hinder part of the machine.
Figures XIX and XX illustrate an arrangement according to which entire wheels
are placed underneath the frames which are represented as being supported on
segments or quadrants in the other figures.
Figure XIX is a side elevation and Figure XX a transverse section of the same..
Figures XXI to XXIX illustrate a number of different forms which the grinding
blocks may assume but I do not limit. myself to the precise forms indicated in the
drawing as these blocks may be made of any other suitable shape in section provided
that the adjacent surfaces are parallel to one another.
Figure XXX illustrates in plan an arrangement of adjusting mechanisin according:
to which the horizontal pivoted bars hereinafter described turn upon centres situated
near their extrémities."
Figure XXXI is a plan and Figure XXXII an end elevation of another modifica-
tion of the adjusting mechanism hereinafter described.
Figure XXXIII and XXXIV represent respectively an end elevation and a detail
partly in section of another modification of the adjusting mechanism.
(a.) Machines with adjustable grinding blocks and one moveable or reciprocating.
frame (Figures I to X).
Upon a strong base plate A A¹ which when necessary can be bolted to the floor.or
foundation there are arranged two standards or frames B B and bearings or plummer
blocks Cand D D¹.
In these bearings D and D' respectively work shafts Erand E' upon which segments
or quadrants. F F and F Fare keyed: These segments or quadrants support two:.

page_text: reciprocating Ushaped frames G and G₁ the sides of which are closed or connected
at the top by removeable plates H H. These frames carry a series of moveable or
reciprocating grinding blocks O. To the frames B B¹ there are bolted transverse
supports J J which support a similar series of fixed or stationary grinding blocks P.
Removeable plates K K Figures V and VI bolted to the upper part of the frames BB
serve to strengthen the said frames and at the same time carry the supports for the
upper edges of the blocks P.
Horizontally oscillating bars L L are supported on strong studs or pivots M M
working in bearings in the bottoms of the frames G and G and in the transverse
supports J and J' connected to the frames B being further supported at their extremities
by antifriction balls or rollers N N Figures I and II.
The grinding blocks P P and OO are provided at their under side with pins QQ
by which they are supported on the pivotted bars or supports L L and are connected
at their upper edges to similarly pivotted bars or supports L' L' by means of similar
pins or studs QQ. The upper supports L' are provided with studs or pivots M' M'
working in sockets in the plates HK H. K' Figures I, II, III, VII, and IX. The
grinding blocks P in combination with the bars I L pivoted on the frames B B¹
thus constitute a jointed frame capable of adjustment in a horizontal plano by moving
the bars L L on their centres M M¹ and the blocks Oform with the bars
pivoted on the moveable frames G G a second frame similarly capable of adjust-
inent this frame being capable of moving bodily to and fro on the rocking segments
or quadrants F and F. The studs or pins QQ may be attached to the blocks P
and O by fixing them in separate holes formed in the upper and lower sides of the
blocks or they may be formed by the ends of rods passing entirely through. the
blocks as indicated by the dotted lines in Figures I and III.
The lower part of the reciprocating frame G Figure I is provided with an arm W
which by means of links Wi Figures I and IV and a pin W" is connected to two
bars forming a lever X.
$
This lever X is fulcrummed on a shaft Y working in the bearing C and has a
suitable reciprocating motion imparted to it by a connecting rod Z operated by a cam
or eccentric not shown in the drawing. By these means a reciprocating motion is
imparted to the frames G G and to the grinding blocks O in the direction of the
length of the latter.. The lever X is formed by two bars passing on both sides of the
connecting rod Z so as to ensure a perfectly regular and uniform action but the lever
may be formed by a single har or any other suitable mechanical equivalent may be
employed for imparting the required reciprocating motion to the grinding blocks.
These blocks are provided on both sides with ridges and furrows the size of which
is regulated according to the degree of fineness to which the materials are to be
reduced. These ridges and furrows are regularly distributed a series of vertical
ridges and furrows being arranged alternately with a series of inclined ridges and
furrows as indicated on the left hand in Figure I or oblique ridges or furrows may be
formed crossing one another as indicated in the same figure or otherwise. The form
or configuration and arrangement of the ridges and furrows may vary according to
the nature of the materials to be operated on. The surfaces of the ridges and furrows
may be rounded concave convex or flat and angular serrated of saw tooth like or
rectangular form in section or in place of continuous ridges the surfaces of the
grinding blocks may be provided with isolated or single teeth. The ridges or their
equivalents on the sides of the grinding blocks may be of the same degree of coarse-
ness or fineness throughout the whole width of the block or they may be graduated
off towards the lower part in the form of steps or they may be made taper or wedge
.shaped the thin ends being directed downwards.
In order to move the acting surfaces of the blocks closer together or wider apart
the bars L L' are caused to turn in a horizontal plane upon the central pivots MM'
until the fixed and reciprocating grinding blocks O and P which are connected to the
said bars by the pins or studs QQ' are moved parallel to themselves and placed in
the required position relatively to one another (Figures VII IX and X). The pivots

page_text: upon which these bars oscillate may be situated at the extremities of the said bars if
preferred in place of being at the centre as in the arrangement illustrated. The
bars L L are prevented by stops N from moving beyond a certain distance or to such
an extent as to bring the grinding surfaces in actual contact with one another. The
grinding blocks are evidently separated to the utmost extent possible when the
bars L L L L are placed at right angles with the blocks as indicated in full lines in
Figure IX and are caused to approach one another by moving the bars to the position
indicated by the dotted lines in the same figure. The parallel arrangement and motion
of the bars L L L L and blocks P O enables the parallelism of the blocks to be
maintained in all positions. To produce the swivelling or rotary motion of the
bars L L L L the upper or lower bars at the front or at the back of the machine are
provided with toothed sectors or quadrants L² as indicated in respect of the upper
bars L' at the front in Figures VII IX and XXX these toothed sectors or quadrants L'
being concentric with the pivots M M¹. These quadrants gear with endless screws or
worms R on shafts R working in bearings S attached to the moveable frames G and
to the stationary frames B.
The shafts R carrying the endless screws are provided at their outer extremities
with ratchet toothed quadrants T T each presenting two sets of ratchet teeth inclined
in opposite directions engaging with separate pawls T¹ T. Levers U U are also pro-
vided on the ends of these shafts being connected together by a bar V Figures I
and II inserted in slots in the ends of the levers U so that it is free to slide therein
and does not impede the longitudinal movements of the shafts R connected to the
reciprocating blocks O.
When the bar V is moved in one direction the levers U are pushed or inclined to
one side and rotary motion is imparted to the endless screws on the shafts R. These
screws or worms engage with teeth in the ends of the bars L' L' and consequently
compel these two bars to turn upon their centres M M in the same directions the
threads of both the worms on the shafts R being similarly inclined.
The grinding blocks O and P being provided with projections or pins Q¹ which
engage with these bars L' L' and also with projections Q engaging with the bars LL
are caused to move parallel with themselves with perfect regularity the bars connected
with the blocks O describing exactly the same arcs as the bars connected to the
blocks P.
.
Each of the shafts R is further provided at its outer extremity with two toothed
segments Thaving ratchet teeth acting in opposite directions which engage with
pawls T. The ratchet segments T and pawis T' are provided for the purpose of fixing
the parts when adjusted in the required positions so that they shall not be liable to
shift in working and alter the distance between the blocks.
If it be required to bring the blocks P closer together for example in order to
obtain a finer reduction of the materials the worm shafts R are turned to the right
by means of the levers U (the pawls which previously prevented the shafts from
turning to the right being lifted or disengaged from the ratchet teeth) until the blocks
are brought as near together as required. The pawls which had been thrown out of
action are then caused to reengage with the teeth of the corresponding ratchet
segments and the shafts R. are thus prevented from turning in either direction. The
grinding blocks P and O being adjusted simultaneously the to and fro or reciprocating
motion of the said blocks is not effected by their being set closer together or wider
apart.
The levers U are provided with square holes which fit on the squared ends of the
shafts R.
The quadrants T are attached to the levers U and can be readily removed from and
replaced on the ends of the shafts R together with the said levers.
Figure IX illustrates another arrangement for producing the simultaneous move-
ment of the shafts R. The levers U U are dispensed with and one of the shafts is
prolonged in the form of a square key m which enters a corresponding hole n in the
end of the other shaft. By means of this arrangement the shafts are compelled to

page_text: run simultaneously and the key m sliding in the hole n admits of their longitudinal
displacement. In this case rotary motion can be imparted to the shafts R by means
of a hand wheel o.
When the shafts have been adjusted by means of the adjusting, mechanism so
that the required distance is obtained between the grinding surfaces the pawls T₁ are
caused to engage with the ratchet teeth of the quadrants T thereby retaining the
blocks in the same position.
To permanently retain the grinding surfaces at the proper distance apart for
reducing certain materials bolts in the plates H H and K K' are screwed up so as
to jam against the bars I and thus securely fix the entire framework in one set
position.
In the plan Figure IX and transverse section Figure X the adjusting mechanisın
is represented in two different positions indicated by full lines and, dotted lines
respectively corresponding to different adjustments of the grinding blocks.
According to another method of adjusting the blocks O P illustrated in Figures XXXI
and XXXII the horizontally vibrating bars L L are dispensed with and the blocks
turn on hinges Q Q so as to be capable of assuming an inclined position as indicated
by the dotted lines in Figure XXXII. These grinding blocks are farthest apart
when in a vertical position and are brought closer together as herein after more fully
described by placing them in the inclined position indicated by the dotted lines.
With the adjusting arrangement illustrated in Figures XXXIII and XXXIV the
grinding blocks O P engage with the plates H K by means of round pins QQ on the
ends of the blocks. The pins QQ work in bearings on the underside of the plates H
and K and are preferably so connected with the blocks near the upper edges thereof
that the blocks tend to assume a vertical position by their own weight. The plates H
and K are connected at one end by strong hinges M M with the frames G G¹ toothed
quadrants N N¹ being provided at the other end. In addition to this there are pro-
longations or arms Ho and Ko (Figure XXXIII on the right) attached to the hinged
plates H and K at the same ends which arms work up and down in a slotted guide.
In this case two toothed wheels T T on the shafts R engage with the teeth of the
quadrants N N and these wheels are turned by hand wheels O and retained or locked
by pawls or catches U. By turning the wheels T T the quadrants N. N¹ are raised
or lowered and raise or lower the plates H and K which rock upon the hinges M M.
The grinding blocks O P are thereby elevated or depressed and all the working
surfaces are brought nearer together or farther apart simultaneously. The full lines
in Figure XXXIII show the blocks in the lowest position and set as wide apart as
possible. They may be brought closer together by elevating them to the position
indicated in the dotted lines.
In order to retain all the grinding blocks in the required position the locking
pawls U are caused to engage with the wheels T T and the screw bolts
Figure XXXIV are tightened in the slotted guides Go so that the arms Ho and Ko
on the covering plates are fixed. With this object a number of screwed holes are
provided in the slotted pillars.
In the machine illustrated in Figures XXXIII and XXXIV the frames G work on
wheels F on a shaft E carried by supports D the said movable frame G being directly
supported by the said wheels the front frame G being firmly connected with the back
frame G by rods f
Figure XXXIII also shows an arrangement by means of which the frames G G¹
are extended laterally and form separate panels in which a number of grinding blocks
are combined with separate adjusting arrangement while all the panels reciprocate upon
the wheels F F and are all set in motion by the same power.
The machines referred to in the paragraphs marked a and c can also be extended
laterally so that the supporting frames G G are repeated and form a number of panels
each enclosing a certain number of grinding blocks all controlled by independent
arrangements but operated by one and the same shaft or lever."
When the adjusting mechanism illustrated in Figures XXXI and XXXII is

page_text: employed the adjustment is effected by turning a hand wheel o on the axis of toothed
wheels T engaging with toothed quadrants N N¹. These quadrants are also provided
with teeth which engage with pawls U U serving to prevent downward motion of the
quadrants and the plates H K can be rigidly, fixed in any desired position by means
of set screws which act upon prolongations Ho Ko on the said plates. The.
shafts R. are connected together by a square key or prolongation m on one of the shafts
engaging with a square hole n in the end of the other shaft Figure XXXI.
By turning the hand wheel to the right the plates H K are moved to the right
and downwards so as to bring the blocks O P closer together. The quadrants NN1
are connected to the said plates by hinges M M. The extensions Ho Ko on these
plates work in vertical slots in the frames G G and must be supported from beneath
before tightening the screws 1.
When the adjusting arrangement illustrated in Figures XXXI, XXXII XXXIII
and. XXXIV is employed the feel hopper e is attached to and moves with the adjust-
able plates. H K and in all cases the hand wheel operating the adjusting mechanism
may be provided with a graduated disc indicating the degree of opening between
the blocks.
In place of the spheres N placed under the ends of the bars L to support the
latter and facilitate their movement the bars L may either work upon small cylindrical
rollers travelling in the ares described by the said bars or may slide upon suitably
curved guides.
The supporting sectors F F¹ are provided with ridges at the edges for the
purpose of preventing any lateral displacement of the frames supported thereon.
To afford further security against such lateral movements of the frames guide
bars g Figures 111 and IV are attached to the frames G and G¹ and slide in guides
or eyes attached to the fixed frames B B. To give additional strength to
the machine the frames B B₁ are connected together by the bars f Figures III
and IV. In place of these bars rods or bars may be, employed provided with
double female screws, which allow of exactly regulating the distance of the frames
of the machine. The said rods may also be secured to the movable U shaped
frames G G¹. The length of these bars is regulated according to that of the
grinding blocks which may be made of any suitable or convenient length. In the
case of small machines the base plates A. A can be made in one piece.
The material to be crushed or comminuted falls from a hopper shaped box c between
the crushing or grinding surfaces suitable means such as valves or slides being provided
to regulate the supply. This feed hopper as well as the collecting hopper may be
divided longitudinally by suitable partitions into separate compartments and the
grinding surfaces may be provided with similar grooves, and furrows or one portion
of the grinding blocks may be set wider apart than the other. By these means it is
possible to reduce the materials to different degrees of fineness in one and the same
machine. In order that the material to be reduced may not accumulate on the
upper sides of the grinding blocks and fall out at the sides the two outermost blocks. O
are provided with a guard a and all the blocks are provided at their ends
with elevations or guards 6 (Figures I III IX and X).
The ridges and furrows of the grinding surfaces extend under the parts provided
with the guards & in order that the materials which may be introduced into this part
in the longitudinal motion of the grinding blocks may be acted upon and reduced
before falling into the collecting hopper d.
To facilitate the entry of the material the grinding blocks are made with inclines
on their upper surfaces so as to form throats or funnels and the acting surfaces with
the ridges and furrows are enlarged or hopper shaped at the upper part so that the
material may enter between the blocks before it is actually engaged with and reduced
by the said ridges and furrows.
By employing two levers such as X one at each end of the machine and substituting
quadrants such as F F¹ for the supports B B' a reciprocating motion may be imparted
to both sets of grinding blocks.

page_text: In order to prevent the reciprocating frames from slipping on the sectors F F¹
studs p figs. I II and IV are provided on the sides of the latter engaging with pro-
jections on the under side of the frames G G₁. The sectors F F are thus constrained
to partake of the same reciprocating motion on the said frames figures I to IV.
In the case of machines in which the reciprocating blocks describe a comparatively
short travel or stroke these blocks may be supported on rocking arms as indicated in
Figures III and III. In these figures the rocking arms are marked F F¹ being
substituted for the rocking quadrants or sectors F F Figures III and IV. These arms
rock on the shafts E E' and are jointed at their upper extremities to the under sido
of the frames G G¹. When this arrangement is employed the worm shafts R are
connected together by a universal joint or coupling.
(b) Machine without adjusting mechanisin and with one reciprocating frame
Figures XI to XIII. The general arrangement of all the parts is the same as that
hereinbefore described except that the mechanism for regulating the spaces between the
grinding blocks and all parts connected therewith L L, M M, N, R, S, T, U and V
are omitted..
The grinding blocks are directly connected by their pins QQ to the bottom
plates G G bearers J J' covering plates H H and connecting plates K K'. The
connecting plates K K' in this case are not laid across the tops of the frames B B'
but are supported on cast iron shoulders or projections.
In operating on a large scale the capacity of the machine may be increased by arrang-
ing several series of grinding blocks one above the other and connecting all the series to
the same working lever X X (sec dotted lines Figures XI XII and XIII). With this
object the segments or sectors F F are extended upwards and suitably arranged for
supporting the several frames G G².
To prevent these sectors from falling over to one side in erecting or taking down
the machine they have loops ii of iron plate bolted to them at the lower part the ends
of which rest upon the base plate A.
This large machine with superposed series of grinding blocks is applicable for
treating materials which require to be quickly reduced to a certain degree of fineness
without sifting. For this purpose the upper grinding surfaces are made considerably,
coarser than the lower and the number of grinding blocks in the upper frames is smaller
than in the lower frames as the partially reduced material takes up more room than
that which has not been acted on. Owing to the longer stroke of the upper series of
grinding blocks resulting from their connection with the working lever at a greater
distance from the fulcrum of the latter the successive reduction of the materials
proceeds under most advantageous conditions.
In Figures XI to XIII the superposed arrangement of the frames is indicated by
dotted lines. Motion may be imparted to all the frames if desired by providing working
levers at both ends of the machine. (c) Machine with mechanism for adjusting the
grinding blocks and two reciprocating frames Figures XIV to XX.
The principal parts of this machine are constructed in precisely the same way as in
the machine described under a but the standards B B are omitted and in their stead
plummer blocks or bearings D1 D2 D3 are provided carrying shafts E E E and E
These shafts carry sectors or quadrants F F F F supporting reciprocating
frames G G¹ G" and G
Both sets of blocks are connected by pins W W and connecting rods or links WW
with a cranked shaft Y' (Figures XVII). In place of this shaft a straight shaft may
be employed being provided with eccentrics working in suitable straps on the ends of
the connecting rods W. In case one only of the frames is required to reciprocate or
move the shaft is arranged to transmit the motion through one crank or eccentric
acting on a cross head and connecting rod. The rotation of the shaft (arranged as
indicated in the drawing) causes one set of grinding blocks to move horizontally in
one direction and causes the other set to move simultaneously and similarly in the
opposite direction.
The shaft can be rotated by hand by means of a crank handle Z' and wheel X¹ fig. XV

page_text: or it may be driven by a belt pulley Z Figure XVI the wheel X¹ acting as a fly
wheel. In place of the sectors or quadrants F F' entire wheels may be employed as
represented in Figures XIX and XX. In this case the underside of the frames G G¹
and G Gare provided with bearings or axle boxes e for the reception of
axles E E. These axles are provided at their extremities with wheels F F travelling
on rails D D. According to another arrangement the frames G G' rest directly on the
peripheries of the wheels F F whose axes in this case work in the frames D D¹. The
sides of the frames G G¹ are bolted to bars f f whereby they are connected to the
frames G and G at the binder part of the machine thus constituting a solid frame-
work travelling upon the wheels F F. If preferred, rods may be substituted for the
plates being secured by nuts screwed on the ends of the said rods.
The blocks O, P, by which the grinding is performed as hereinbefore described may
be composed of any suitable material, possessing sufficient hardness to reduce the
materials treated. For example, the said blocks may be made of any description of
iron or steel or other suitable metal or of porcelain glass carthenware stone or the
like. The other parts of the machine are made of iron steel brass or other suitable
materials. The machine is provided with a casing of wood or sheet metal to protect
it from dust, this casing being omitted in the drawings in order to shew the working
parts.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is:
―
1. Improvements in mills or machines for crushing grinding or comminuting
minerals chemicals roots grain malt pulse sugar, and other produce or materials con-
sisting in the employment of a suitable number of grinding blocks (O, P) of any
convenient section fixed or adjustable towards or from one another supported on wheels
or sectors and provided with ridges and furrows or their equivalents being connected
at their ends so as to form two series of blocks, the blocks of one series working
between the blocks of the other series and a reciprocating motion being imparted to
one or both series of blocks in the direction of their length by any suitable means so
as to crush, grind or reduce the materials or substances introduced between the grinding
surfaces of the said blocks substantially as hereinbefore described.
2. In a mill or machine of the type hereinbefore described and claimed, the com-
bination of a number of series of grinding blocks, arranged one above the other and
operated by the same lever, substantially as hereinbefore described.
3. In a mill or machine of the type hereinbefore described and claimed, the arrange-
ment for adjusting the grinding blocks relatively to one another by means of bearers or
bars LL provided with toothed sectors or quadrants gearing with worms or endless
screws on shafts R, operated directly by levers U and rods V or by the intervention
of ratchet quadrants or sectors or wheels T for the purpose of placing the grinding
surfaces closer together or wider apart, substantially as hereinbefore described.
4. The arrangement for adjusting the grinding blocks suspended on hinges Q1 Q¹by
displacing them from a vertical position to an inclined position the grinding blocks
being moved by turning the toothed wheels TT and being fixed in position by pawls
or catches UU and screws substantially as hereinbefore described.
5. For machines in which the grinding blocks are worked with a short stroke the
employment in place of the quadrants TT of supports keyed upon shafts E E¹ and
connected by a hinged joint with the transverse frames G G substantially as herein-
before described.
6. The segments or quadrants L L having their centre of rotation situated at
the end of the quadrants substantially as hereinbefore described.
7. The employment of sliding surfaces in place of the balls or rollers N for support-
ing the support or quadrant L substantially as hereinbefore described.

page_text: 8: The modification of the arrangement referred to in the 4th claiming clauso
consisting in suspending the grinding blocks freely from the covering plates H K by
hinges in place of hinges at both ends the said covering plates moveably attached to
the frames GG by hinges M M being raised by quadrants N N' and toothed
wheels T T in order to bring the grinding blocks uniformly nearer together the
return or running back of the plates H and K being prevented by the catch or
pawl U substantially as hereinbefore described.
9. The lateral extension of the machine by connected U shaped supporting
frames so as to form a series of groups of grinding blocks with separate adjust-
ment controlled by the same operating mechanism substantially as berein before
described.