Year: 1885

page_text: I, WILLIAM BEILBY AVERY of 12 Digbeth, Birmingham in the County of
Warwick, Machine Maker do hereby declare the nature of this invention to be as
follows:-
In beam scales of the ordinary pattern for commercial purposes in which broad
and strong knife edges and bearings are essential, it is found exceedingly difficult,
to attain the necessary strength and breadth and at the same time maintain
perfect truth and accuracy in the parts, without which absolute correctness in
weighing cannot result.
Now the object of the present invention is to facilitate the construction of beam
scales which will fulfil the requirements both of strength and accuracy.
In constructing beam scales according to my invention I take a beam, and on its
under side, at the middle of its length, and transverse thereto, I mount a short
length of hardened steel or of agate, preferably triangular in cross section, the apex
of the triangle forming the knife edge, and the base lying close against the beam.
The knife edge is secured to the beam by plates on either side thereof fastened by
screws to the beam. The edges of the plates next the knife edge may be bevelled
off to overlie the sloping sides of the triangle. Should it be necessary to adjust
the position of the knife edge, this may be done by loosening the screws of the
plate on one side, and tightening the screws of the plate on the other side, thereby
pressing the knife edge sideways in the direction of the length of the beam. In
this way very accurate lengthwise adjustment can be effected.
The beam is carried by a link and the knife edge bears upon a loose bearing
block of any suitable material within the link. The bearing block is so formed as
to be capable of an endwise rocking movement independent of the link, in order to
give an even bearing to the knife edge, notwithstanding any slight lateral tipping
of the beam.
The ends of the scale beam are each provided with knife edges and bearings
similar to those, described above, but their arrangement is inverted, the knife edges
being above the beam, with the bearing blocks overlying them and the links
depending from the bearing blocks to carry the trays below.
From the above description it will be evident that beam scales constructed
according to my invention will be capable of weighing with the greatest accuracy,
as the broad knife edges may be "lapped" perfectly true before or even after
being fixed on the beam, and they have the additional of bearing upon" wide and
ever even surfaces, which surfaces can be prepared with the greatest nicety.
1 1

page_text: Improvements in Beam Scales.
I, WILLIAM BEILBY AVERY of 12 Digbeth, Birmingham in the County of
Warwick, Machine Maker, 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:-
In beam scales of the ordinary pattern, for commercial purposes, in which broad
and strong knife edges and bearings are essential, it is found exceedingly difficult
to attain the necessary strength and breadth, and at the same time maintain
perfect truth and accuracy in the parts, without which, absolute correctness in
weighing cannot result.
Now the object of the present invention is so to construct beam scales, that the
requirements both of strength and accuracy will be fulfilled.
In constructing beam scales and steelyards (for the invention is as applicable to
steelyards as to beam scales proper) according to my invention, I mount on the
underside of the beam, and transverse thereto, a short length of hardened steel or
of agate, preferably triangular in cross section, the apex of the triangle forming
the knife edge, and the base lying close against the beam.-The triangular piece or
knife edge is held in position under the beam by two plates placed one on either
side thereof, and secured to the beam by screws.-The edges of the plates next the
knife edge may be bevelled off to overlie the sloping sides of the triangle. Should
it be necessary to adjust the position of the knife edge, this may be done by
loosening the screws of the plate on one side, and tightening the screws of the
plate on the other side, thereby pressing the knife edge sideways in the direction
of the length of the beam. In this way, very accurate lengthwise adjustment can
be effected.
The beam is carried by a link, and the knife edge bears upon a loose bearing
block of any suitable material within the link. The bearing block is preferably so
formed as to be capable of an end wise rocking movement, independent of the link,
in order to give an even bearing to the knife edge, notwithstanding any slight
lateral tipping of the beam.
The ends of the scale beam are each provided with knife edges and bearings
similar to those described above, but their arrangement is inverted, the knife edges
being above the beam, with the bearing blocks overlying them, and the links
depending from the bearing blocks to carry the trays below.
From the above description, it will be evident that beam scales and steelyards
constructed according to my invention will be capable of weighing with the
greatest accuracy, as the broad knife edges are detachable, and may therefore be
lapped" perfectly true, both before and after application to the beam.
They have the additional advantage of bearing upon wide and ever even surfaces,
which surfaces can be prepared with the greatest nicety.
In order to take the weight off the knife edge when not weighing, I form a
notch or recess in the centre of the knife edge to receive a regulating screw, which
is inserted through a tapped hole in the link and bearing block. By screwing
down the screw, which is provided for the purpose with a winged or milled head,
I raise the block off the knife edge, in which position it remains until the machine
is again required for use.

page_text: In Sheet I of the accompanying drawings, I have shewn my invention as applied
to beam scales, and in Sheet II as applied to a steelyard.
Fig. 1, Sheet I, is a side view of a scale beam; Fig. 2 is a plan view of the
same; Fig. 3 is a transverse section on the line of Fig. 1, and Fig. 4 is a
transverse section on the line y y of Fig. 1. Fig. 5, Sheet II, is a side view of a
steelyard. Similar letters of reference designate the corresponding parts in all the
Figures.
A is the beam, which is supported by a link B. The beam is provided with a
central knife edge C, preferably of agate, which rests upon a bearing block D, of
agate, or hard steel, carried by the link B.
The knife edge C, which is shewn of triangular form in cross section, extends the
entire breadth of the beam, and is secured to the underside thereof by bevel edged
gripping plates a a', secured by screws to the beam. The object of thus securing
the knife edge is to provide for its adjustment on the beam, and its ready detach-
ment therefrom.-This adjustment is effected by slackening one plate and tightening
up the other, whereby a perfect balancing of the beam A may be readily effected.-
The ends of the bearing block D are recessed (see Fig. 4) to fit into the link B, and
the outer side of the block is rounded longitudinally to allow it to rock within the
said link, and thus maintain, in the well known manner, the parallelism of the
bearing block and the knife edge.
The ends of the beam A are similarly provided with links b, knife edges c, and
bearing blocks d, constructed in the manner above described, but their arrangement
is inverted; thus, the knife edges c are secured above the beam A by bevel edged
gripping plates a³ a³, and receive the rocking bearing blocks d carrying the
links bb. The scales not shown in the drawing are attached to the links b b.
Referring now to Fig. 5, E is the steelyard provided with links B. b b, knife
edges Cc c, and rocking bearing blocks D d d, all of which parts are similar to
the corresponding parts described with reference to the scale beam, and con-
sequently need no further description.—The gripping plates a a¹ a³ and a³ serve to
secure the knife edges in place as before.
The suspension links may, if desired, be each provided with a thumb screw e,
which passes through the bearing block into a recess or notch cut in the knife
edge at the centre of its length. This screw, when screwed down into the notch,
will raise the link off the knife edge, and thus prevent the wearing away of the
knife edge when the machine is not at work.
Having now particularly described and ascertained the nature of my said
Invention and in what manner the same is to be performed, I declare that what
I claim is:-
Fitting scale beams and steelyards with adjustable knife edges in the manner
and for the purpose above set forth.