IMPROVEMENTS IN THE CONSTRUCTION OF CENTRES AND BEARINGS OF SCALES, SCALE BEAKS, AND WEIGHING MACHINES
Year: 1869

page_text: LETTERS PATENT to Henry Parnall and John Parnall, of the Firm
of Henry Parnall and Sons, of Bristol, in the City and County of
Bristol, Scale and Weighing Machine Makers, for the Invention
of "IMPROVEMENTS IN THE CONSTRUCTION OF CENTRES AND BEARINGS OF
SCALES, SCALE BEAKS, AND WEIGHING MACHINES."
Scaled the 16th July 1860, and dated the 18th January 1869.
PROVISIONAL SPECIFICATION left by the said Henry Parnall and
John Parnall at the Office of the Commissioners of Patents, with
their Petition, on the 18th January 1869.
We, HENRY PARNALL and JOHN PARNALL, of the Firm of Henry
Parnall and Sons, of Bristol, in the City and County of Bristol, Scale
and Weighing Machine Makers, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN THE CONSTRUCTION OF CENTRES AND

page_text: follows:-
This Invention relates to certain improvements in the construction
and arrangement of centres and bearings of scales, scale beams, and
weighing machines where agate or other hard stone is applied in con- ;
nection with a moving steel-edge bearing or centre, the object being
to diminish friction and render the working parts more durable and
Insting.
We cut out or cast sockets or cavities in the bearings and apply the
agate or other hard stone by inserting it within such cavities and fixing
it therein by an adhesive material or compound, and on each side of the
agate transversely to the line of the pivot or moveable bearing we apply
a steel plate set between the agate and the sides of the socket; the
surfaces or edges of these two plates are made concave, and at a lower
level than the curvilinear surface of the agate bearing, so that the V edge 1
of the pivot alone rests on the agate, leaving the shoulders of the pivot
to merely bear against the sides of the plates. This is in those cases
where the agate is beneath the rocking pivot which rests on the agate,
but where the agate surface rests on the pivot the steel plate is of course
reversed, and its convex surfaces are over the surface of the pivot, leaving
the agate only to bear on the rocking Vedge, the apex of which is
inverted. The steel plate may be applied to one side only of the agate,
more especially in the central beam bearings, where the pivot is fixed
with a square head in and through the beam, and the two V edges extend
outwards on each side of the beam on two agate blocks. In this case
the shoulder within each edge would bear on the plates, one on each
agate surface. But where the scale or balance with the inverted arched
agate bearing is supported at cach end of the scale beam one agate block
is sufficient, and since the edge must then be within two shoulders it
follows that two plates of steel must be applied, one on each side of the 8
agute block.
V
Hardened iron may in some cases be used instead of the steel plates
T

page_text: By these arrangements the ends of the rocking pivots cannot wear, as
they are never subjected to friction, which they have hitherto been in
machines where agate or other hard stone is employed; moreover tho
accuracy and efficiency of the machine are materially increased by the
SPECIFICATION in pursuance of tlie conditions of the Letters Patent,
filed by the said Henry Parnall and John Parnall in. the Great
Seal Patent Office on the 17th. July 1869..
TO ALL TO WHOM THESE PRESENTS SHALL COME, we,. HENRY
PARNALL and. JOHN PARNALL, of the Firm of Henry Parnall and Sons,
of Bristol, in the Oity and County of Bristol, Scale and Weighing
Machine Makers, sond. greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eighteenth day of January, in the
year of our Lord One thousand eight hundred and sixty-nine, in the
thirty-second year of Hor roign, did,.for Herself, Her heirs and successors,
give and grant unto us,, the said Henry Parnall and John Parnall,
Her special licenco that we, the said Henry Parnall and John Parnall,
our executors, administrators, and assigns, or such others as we, the
said Henry Parnall and John Parnall, our executors, administrators,
and assigns, should at any time agree witli, and no others, from time
to time and at all' times thereafter during the term therein expressed,
shoukl and lawfully might make, use, exercise, and vend, within the
United Kingdom of Great Britain and Ireland,, the Channel Islands,
and Isle of Man, an Invention for "IMPROVEMENTS IN THE CONSTRUCTION.
OF CENTRES AND BEARINGS OF SCALES, SCALE BEAMS, AND WEIGHING MACHINES,"
upon the condition (amongst others) that we, the said Henry Parnall
and John Parnall, our executors or administrators, by an instrument
in writing under our, or their, or one of their hands and scals,
should particularly describe and ascertain the nature of the said
Invention, and in what manner the same was to be performed, and
cause the same to be filed in the Great Seal Patent Office within six
calendar months next and immediately after the date of the said Letters
Patent.

page_text: NOW KNOW YE, that we, the said Henry Parnall and John Parnall,
do hereby declare the nature of our said Invention, and in what manner
the same is to be performed, to be particularly described and ascertained
in and by the following statement :-
Our Invention relates to certain improvements in the construction
and arrangement of centres and bearings of scales, scale beams, and
weighing machines in which agate or other hard stone is applied in con-
nection with a moving steel-odge bearing or centre, the object being to
diminish friction and render the working parts more durable and
lasting.
We cut or cast sockets or cavities in the bearings, and apply the agate
or other hard stone by inserting it within such cavities and fixing it
therein by an adhesive material or compound, and on each side of the
agate transversely to the line of the pivot or moveable bearing we apply
a steel plate set between the agate and the sides of the socket; the
surfaces or edges of these two plates are made concave and at a lower
level in the centre than the curvilinear surface of the agate bearing, so
that the V edge of the pivot alone rests on the agato, leaving the
shoulders of the pivot to merely bear against the sides of the plates.
This is in those cases where the agate is beneath the rocking pivot which
rests on the agate surface, but where it rests on the pivot the steel plate
is of course reversed, and its convex surfaces are over the surface of the
pivot, leaving the agate only to bear on the rocking V edge, the apex of
which is inverted. The steel plate may be applied to one side only of
the agate, more especially in the central beam bearings, where the pivot
is fixed with a square head in and through the beam, and the two
V edges extend outwards on each side of the beam on two agate blocks;
in this case the shoulder within each V edge would bear on the plates,
one on each agate surface. But where the scale or balance with the
inverted arched agate bearing is supported at each end of the scale beam
one agate block is sufficient, and since the V edge must then be within
two shoulders, it follows that two plates of steel must be applied, one on
cach side of the agate block.

page_text: or balance so as to be a solid socket, in which the agate is set, and to
avoid the necessity of adjusting the plates of metal to the bearing.
By these arrangements the ends of the rocking pivots cannot wear, as
they are never subjected to friction, to which they have hitherto been in
machines where agate or other hard stone is employed; moreover tho
accuracy and efficiency of the machine are materially increased by tho
novel construction and arrangement of the bearing surfaces.
In order that our said Invention may be completely understood wo
annex the accompanying Drawings, in which Fig. 1 represents a side
view of a scale beam with two centre pins a, one on each side of the
beam, and working on agate bearings b, shewn in dotted lines, and let
into cavities, sockets, or grooves; in this example the steel or hardened
iron bearings are only on the interior surfaces of the agate nearest tho
beam, and on which the breasts or shoulders of the pivots work.
Figs. 2, 3, and 4 show various shaped bearings in which the agato
or other hard stone is inserted; in some cases the fixing of the plates
may be dispensed with, and the recess for the agate may be formed or
cast of a shape similar to that presented by the insertion of supple-
mentary plates, in which instances these parts should be hardened so as
to supply an equivalent for the hardened iron or steel plates, so that tho
agate may at once be inserted and fixed in the socket. Figs. 2 and 3
are examples where the V edge rests on the agato, Fig. 3 being suitable
to the beam Fig. 1, and Fig. 4 being suitable for the hanger supporting
the scale.
Fig. 5 shews the contro pin a as applied to the agate in Fig. 1, the
edges a' of which are lowered a sufficient distance to allow the breast to
work against the steel plate or hardened surface alone.
Fig. 6 shews one of the steel plates c (also representing the form of
the hardened iron cast or formed in the recess or socket); the upper
surface or edge comes below the surface of the agate bearing or stone, so
as to permit the V edge of the centro pin to work freely thereon. This
plate is shown in Fig. 8 placed by the side of the agate block.
The curvilinear edgo of tho plates to protect the agate and forming
AL
AA

page_text: structed that while being lower in the centre to allow of the V knife
edge working freely on the agate, it is raised at each end above the level
of the agate, so as to protect the upper side edges of the agate from
becoming chipped or injured by the action of the centro pin in working,
as shewn in Figs. 2, 3, and 4.
From these examples it will be seen that various modifications may be
made in the arrangement of the parts according to the scale or beam
bearings required, as well as in weighing machines generally, to every
description of which agate or hard stone bearings may be applied by
means of our Invention, and in many of which steel bearings are now
used.
We also apply steel bearings enclosed in metal boxes in the manner
and form described in reference to agate, thus affording great facility of
their removal for repairing and replacing, as well as the advantage of
enclosing the centres and protecting them from dust and damp.
'
Ilaving now described the nature of our said Invention, and the
manner in which the same is to be performed, we would remark that
we do not limit ourselves to the exact details or configuration of parts
expressed and shewn, as the same may obviously be modified according
to the description of the machine to be constructed, neither do we make
any claim to the mere application to scales, scalo beams, or weighing
machines of agate or hard stone for bearings, as the same has been
known and used hitherto; but what we claim and desire to be secured
to us by the herein in part recited Letters Patent is, the construction of
centres and bearings of scales, scalo beams, and weighing machines
generally by casting or forming sockets, recesses, or cavities in the
positions and manner described, either with a side plate or plates of steel
or hardened iron placed therein or with a corresponding construction in
the cutting or casting of such sockets or receptacles, and by forming
the V centre pins or pivots with breasts, shoulders, or, side bearing
surfaces or edges to bear on such plates or solid hardened bearings, agate
or hard stone being placed, fixed, or set in such cavities or sockets to
form bearings for the V edges of the centre pin, pivot, or other V edgo
bearing alone, whereby the friction on the centres and bearings will be
greatly decreased, and the agate protected by our breast plates from
becoming chipped or injured by concussion or otherwise in the working

page_text: of the centre pin thereon, and the parts rendered moro durable and
lasting than by other applications of agate or stone to such machines,
substantially as herein specified and shewn.
In witness whereof, we, the said Henry Parnall and John Parnall,
have hereunto set our hands and scals, this Fifteenth day of
July, in the year of our Lord One thousand eight hundred and
sixty-nine.
Witness,
ALFRED IY. PHILIPPS.
HENRY PARNALL. (L.s.)
JOHN PARNALL. (L.B.)