IMPROVEMENTS OF WEIGHING MACHINES AND SCALE BEAMS
Year: 1880

page_text: LETTERS PATENT to William Beilby Avery, of Birmingham, in the County of
Warwick, for an Invention of "IMPROVEMENTS
OF WEIGHING MACHINES AND SCALE BEAMS."
IN THE CONSTRUCTION
(Void by reason of the Patentee having neglected to file a Specification in
pursuance of the conditions of the Letters Patent.)
PROVISIONAL SPECIFICATION left by the said William Beilby Avery at
the Office of the Commissioners of Patents on the 10th December 1880.
WILLIAM BEILBY AVERY, of Birmingham, in the County of Warwick,
"IMPROVEMENTS IN THE CONSTRUCTION OF WEIGHING MACHINES AND SCALE
BEAMS."
It has been found that the knife edges hitherto employed in the construction of
weighing machines and scale beams are liable to become worn unequally by reason
of the grinding and rubbing action of the bearing surfaces in contact with them, the
accuracy of the said machines being thereby greatly impaired.
This is especially the case in platform and road weighing machines such as are
used for heavy goods, the mere act of placing the goods in position on the platform
frequently causing the same to be beavily jarred, and imparting to it a lateral
thrust which tends to wear down the knife edges on one side or the other. Or it
may be the platform is made to tilt, and the whole weight of the goods is thus
brought to bear upon one end only of the knife edge, which will in time cut for
itself a new and misplaced bearing surface.
Now the object of this Invention is to provide universally adjustable bearing
blocks for the knife edges to work upon, so that the strain on each knife edge may
always be equally distributed along it and be always transmitted in a vertical
direction.
The principle upon which these universally adjustable bearing blocks are
constructed is that they shall be capable of four distinct movements, two of which
movements will neutralize the effects of any lateral strain or jar upon the knife

page_text: edges, the remaining two movements distributing the strain equally along the
knife edges.
In carrying out this principle of construction I form my universally adjustable
bearing blocks with flat grooved or concave surfaces (as usual) against which the
fixed lever or beam knife edges bear, and also with knife edges on which each of
the said blocks is free to rock in a vertical plane at right angles to that passing
through the fixed knife edge before named, the knife edges of each bearing block
being in the same horizontal plane as that passing through the lever knife edge.
In all cases the bearing block with its flat, grooved, or concave surface is formed
of a separate and detached piece of hardened steel, and is provided with a knife
edge whereby it is rendered capable of the double oscillating movement above
explained. It will thus readily adapt itself to any unequal distribution of weight,
and the weight will be equally distributed between its surface and the knife edge
in contact therewith. The details of construction will vary somewhat to suit the
different classes of weighing machines to which the self adjusting bearing block
is applied. In adapting this bearing to a platform or sack weighing machine, for
example, I should proceed as follows:-An arm of iron is attached to or forms part
of the underside of the platform or frame which supports the platform and
transmits the weight placed thereon to a link which has a bearing surface which
works upon the knife edges forming part of the self adjusting bearing block. The
weight of the platform is thus transmitted in a vertical direction to the bearing
block by means of this arm and link (which allow of sufficient play in any
direction to absorb lateral jarring strain), and thence to the fixed lever or beam
knife edge on which such block rests.
As before mentioned the adjustable bearing block has a flat grooved or concave
under surface which rests on the fixed knife edge carried by the lever, which lever
is supported by means of a second fixed knife edge resting on a self adjusting
bearing block, which may be either fixed or connected with the frame or box of
the machine by a link.
The universally adjustable bearings before mentioned may be made and attached
in various ways, but the chief point to be observed in their construction and fitting
is to see that the point at which pressure is transmitted from the platform through
the arm to the link is immediately beneath the centre of the point of attachment
of the said arm, and also immediately beneath the centre of the self adjusting
bearing block when the parts are in their normal position, resting upon the lever
knife edge.
Bearings thus constructed may be nsed in an inverted position to suit certain
details of construction in the machine to which they are to be applied, and in fact
these automatically adjusting bearings are applicable to all classes of weighing
machines.