Improvements in Weigh Bridges, Weighing Machines, Dynamometers, and similar Instruments or Apparatus for Measuring Weight or Force.
Year: 1887

page_text: Date of Application, 6th May, 1887
Complete Left, 5th Jan., 1888
Complete Accepted, 10th Feb., 1888
PROVISIONAL SPECIFICATION.
Improvements in Weigh Bridges, Weighing Machines, Dynamometers,
and similar Instruments or Apparatus for Measuring Weight or
Force.
I JAMES YATE JOHNSON of 47 Lincolns Inn Fields in the County of Middlesex
Gentleman do hereby declare the nature of this Invention which has been communi-
cated to me from abroad by Pierre Guillaumin of Voiron, Isère in the Republic of
France Engineer to be as follows:-
This Invention relates to weighing and other similar apparatus and consists in
providing such apparatus with means as hereinafter described for testing or verifying
their accuracy without the employment of the heavy weights heretofore required for
testing and adjusting instruments of this description. A weighing apparatus arranged
according to this Invention thus presents the double advantage of containing in itself
the means for checking its accuracy and of dispensing with the heavy test weights
usually employed.
In order to effectually verify the action of a weigh bridge for example graduated
from zero to the maximum load it has heretofore been necessary to employ either
powerful machines or weights in sufficient quantity to test every notch of the steel
yard. In the case of a weighbridge capable of weighing 20 tons for example it is
absolutely necessary to be provided with 20 tons of weights or heavy bodies in order
to verify the action of the mechanism whereas by means of this invention the same
result is enabled to be attained with small fractions say 10, 100 1000 or 10.000 of this
weight according as the proportions of the transmitting levers is 1 to 10, 1 to 100,
1 to 1000 or 1 to 10,000 for example. In short by means of this invention an opera-
tion which has usually required 12 hours can be performed in about 15 minutes.
A weighbridge arranged according to this invention is supported upon a system of
levers calculated to reduce the pressure in certain proportions and this reduced
pressure representing a known fraction of the weight is transmitted through a suitable
suspension rod to a graduated beam or steel yard carrying the usual sliding weights
and resting on knife edges being provided at one extremity with a scale pan for the
CD
7

page_text: reception of small test weights as hereinafter explained-This extremity of the said
steel yard is also connected with a second graduated beam or steel-yard similarly
provided with a sliding weight or weights. The first steel yard acts as a lever of the
second order, the connection with the suspension rod being regarded as the weight in
which case the second steel yard acts as a lever of the first order. The first steelyard
is provided with two unequal sliding weights for example working on different series
of notches or graduations the smaller weight nearest the fulcrum being employed to
mark the units and the larger weight marking hundreds whilst a third sliding weight
placed on the second steelyard marks thousands, assuming the apparatus to be con-
structed for weighing on the decimal system but of course the graduations may be
regulated for any other desired system of weights. A second scale pan attached to
an extension of the first steel yard and on the opposite side of the fulcrum to the
point where the suspension rod is attached serves for regulating the tare. The pressure
transmitted to the second steelyard is reduced in the proportion of 10 to 1 for
example by the action of the first steel yard and in some cases the second steelyard
may be dispensed with or may be combined with other levers marked with different
graduations.
The first steelyard which forms an essential part of the apparatus firstly enables
the accuracy of its own action to be verified and also by extension that of all the levers
of the bridge with which the apparatus is connected and secondly it enables the
reduced or fractional weights to be verified which being placed on the scale pan at
the end of the steel yard represent or perform the functions of the full or complete
weights which in verifying the weighbridge in the usual way would have to be
placed upon the bridge in order to enable the accuracy of the graduations to be
ascertained.
The weighing operation is performed with the improved apparatus in the same way
as with ordinary apparatus by sliding the weights along the steelyards until an
equilibrium is obtained and the accuracy of the indications can be checked at all times
if required by simply placing weights representing known fractions of the weight on
the bridge or platform and corresponding to the proportions of the levers, upon the
scale pan at the end of the steelyard-The same system of verification is evidently
applicable to platform and other weighing machines, dynamometers and other similar
instruments.

page_text: COMPLETE SPECIFICATION.
Improvements in Weighbridges, Weighing Machines, Dynamometers,
and similar Instruments or Apparatus for Measuring Weight or
Force.
I, JAMES YATE JOHNSON of 47 Lincolns Inn Fields in the County of Middlesex
Gentleman do hereby declare the nature of this Invention which has been
communicated to me from Abroad by Pierre Guillaumin of Voiron Isère in the
Republic of France, Engineer and in what manner the same is to be performed to
be particularly described and ascertained in and by the following statement :-
This Invention relates to weighing and other similar apparatus and consists in
providing such apparatus with means as hereinafter described for testing or verifying
their accuracy without the employment of the heavy weights heretofore required for
testing and adjusting instruments of this description A weighing apparatus arranged
according to this Invention thus presents the double advantage of containing in itself
the means for checking its accuracy and of dispensing with the heavy test weights
usually employed.
In order to effectually verify the action of a weighbridge for example graduated as
usual from zero to the maximum load it has heretofore been necessary to employ
either powerful machines or weights in sufficient quantity to test every notch of the
steel yard. In the case of a weighbridge capable of weighing 20 tons for example it
is absolutely necessary to be provided with 20 tons of standard weights or heavy bodies
in order to verify the action of the mechanism whereas by means of this Invention the
same result is enabled to be attained with small fractions of this weight regulated
according to the proportions of the transmitting levers as hereinafter explained. In
short by means of this Invention an operation which has usually required 12 hours
can be performed in about 15 minutes.
And in order that the said Invention may be fully understood I shall now proceed
more particularly to describe the same and for that purpose shall refer to the several
figures on the annexed sheet of drawings the same letters of reference indicating
corresponding parts in all the figures.
These drawings illustrate the application of the Invention to a weighbridge for
weighing loaded vehicles and the like from which it will be readily understood that
the same principles are equally applicable to other instruments for testing or measuring
weight or force such as dynamometers for testing cements or strength of materials or
other like instruments in which steelyards or levers are employed to reduce or multiply
the pressure applied at one extremity of the system.
Figure 1 of the accompanying drawings is a view in perspective shewing the
indicating mechanism of a weighbridge provided with means for verifying its accuracy
according to this Invention.
Figure 2 is a diagram illustrating in plan the arrangement of the levers underneath
the platform.

page_text: Figure 3 is a diagram illustrating the action of the levers.
The weighbridge illustrated in the drawing. is arranged for use with the decimal
system of weights commonly employed on the continent but it is evident that the same
principle of construction and verification may be employed with any other system of
weights by suitably modifying the arrangements of the parts.
Referring to Figure 3 P¹ indicates the weight on the bridge or platform receiving
the vehicles or articles to be weighed. The weight or pressure of this platform is
received in the first instance by a lever Ll having its fulcrum at L-In practice two
of these levers are employed as indicated in figure 2 but they act as one and may be
regarded as one for the purposes of this description. The pressure of this lever is
received by a second lever Cc having its fulcrum at C¹ and connected by a tension
rod X provided with hooks or their equivalents for the reception of weights to a third
lever R formed by two arms Ff having its fulcrum at F2 and forming part of the
indicating mechanism (figures 1 and 3) which may be situated in a counting house
or any other convenient position. The arm F of the lever R is connected by a link B
figure 1 to a lever R¹ having its fulcrum at R2 and is provided with two graduated
scales Tt (figure 1) and two sliding weights Qq the lever R¹ being also provided with
a graduated scale T and a sliding weight Q-In the example illustrated the divisions
on the scale t indicate units of weight or kilograms those on the scale T indicate
hundreds of kilograms and those on the scale T¹ thousands of kilograms All the
scales have their zero mark at the left hand extremity and are read from left to right
this being a great convenience in using the apparatus.
The indicating mechanism is mounted on a stand or pillar M as indicated in figure 1
which is provided with a box or recess M¹ closed by a suitable door or flap and
containing a series of weights used in testing the accuracy of the machine as herein-
after explained. A scale pan B¹ for the reception of test weights is suspended from
the lower extremity of the link B and the lever Ff is provided with an extension or
arm to the extremity of which is attached a link carrying a balancing weight S and
a hook A' for the reception of additional weights used in testing the instrument.
Each of the levers in the example illustrated is calculated to reduce the weight in
the proportion of 10 to 1 thus the lengths of the arm I and c of the levers Lland Ce
are exactly one tenth of the total length of the levers L and C c. The arms Ff
and R¹ of the levers R R' are arranged in a similar manner the arm being one
tenth of the length of the arm R' and the arm of being one tenth of the total length of
the lever R. The extension or extra arm f' is made equal to f and consequently a
weight of say 1000 kilograms on the bridge (P¹) will if the levers are accurately
proportioned be exactly balanced by 10 kilograms suspended at A'. The length of
the lever arm f¹ is equal to the length of the lever arm for one tenth of the total
length of the lever R and consequently 10 kilograms at A¹ at the extremity of the
arm will balance 1 kilogram at X" in the scale pan B¹ at the extremity of the
arms Ff composing the lever R. The removal of ten kilograms from A' has the same
effect on the system of levers as the placing of one kilogram at B₁ or to the placing of
1000 kilograms at P¹ and one kilogram at B' being equivalent to 10 kilograms at A'
is equivalent to 1000 kilograms at P¹.
The action of the indicating levers R and R¹ is tested or verified as follows in the
case of an apparatus constructed according to this Invention and capable of weighing
up to 10,000 kilograms as in the example illustrated. This apparatus is provided with
a series of test weights from one to ten kilograms placed in the receptacle M² in the
stand or pillar M. After ascertaining that the machine oscillates freely and balances
properly (without a load) a test weight of 1 kilogram is taken from the box M¹ and
suspended from the point A figure 1 forming one extremity of the lever arm fand by
means of a standard weight or otherwise the length of the arm fis proved to be truly
equal to the arm f¹. The correctness of all the test weights in the series may also be
proved by these means 10 kilograms of test weights are then placed at A¹ and 1 kilo-
gram at B¹ to prove that the proportion of the lever arms forming the lever R
and f¹ is exactly 10 to 1 (F += 10 and F +f' = 10,¹ being equal to f). The

page_text: accuracy of the essential element of the system is thus established. To prove that the
two levers Ll and Cc reduce the weight in the proportion of 100 to 1 the test weight
of 10 kilograms is placed at X" that is to say in the scale pan B¹ and any convenient
weights or articles are suspended from the hook at A¹ so as to exactly balance the
10 kilograms at B'. The weights at A which are known to be exactly 100 kilograms
by reason of the proportion of the lever arms Ff and f¹ being then placed upon the
platform or bridge at P will if the levers under the platform are correct, be exactly
balanced by a test weight of 1 kilogram placed at A. (The 10 kilograms at B' being
removed). To ascertain whether the action of the levers under the platform is
effected by their flexure or bending under the strain of heavy loads the latter part of
this operation is repeated after a loaded vehicle or other heavy weight near the
maximum weight for which the machine is constructed has been placed upon the
platform or bridge. It is evident that if under these conditions the mechanism con-
tinues to shew the same sensitiveness and the proportion of the levers is found to
remain the same while thus exposed to the heaviest load the conditions of equilibrium
are not affected that is to say remain unaltered by flexure or bending of the said
levers.
The three levers L, I, Cc and R (F) being proportioned as described reduce the
weight transmitted in the proportion of 1000 to 1 so that a weight of 1 kilogram for
example at B on the lever R (Fƒ) has the same effect relatively to the lever R¹ as
1000 kilograms on the bridge or platform P. The lever R¹ can thus be tested for any
desired weight in thousands of kilograms from one thousand to ten thousand by simply
placing test weights of from one to ten kilograms in the scale pan B¹ where they
produce the same effect as if they were multiplied by a thousand and placed on the
platform or bridge at 'P¹. The accuracy of the indications given by the sliding
weights Qg on their respective scales is verified as hereinafter explained. The sliding
weight Q on the upper lever R¹ being employed to indicate thousands of kilograms
only the accuracy of the scale T can be tested for each notch by placing all the test
weights (from 1 to 10 kilograms) in turn in the scale pan B¹ and if the machine is
in order the slider Q₁ will then balance these weights at the notches indicating the
corresponding multiple of such weight. Thus with one kilo suspended at XⓇ the
machine should be in equilibrium when the slider Q¹ is in the notch marking
1000 kilograms with two kilograms at X" the slider should balance at the 2000 notch
and so on.
To verify the indications of the scales on the lever R the sliders Q 9 on this lever are
put in the O notch and the slider Q' on the scale of thousands on the upper lever is
placed in the notch indicating 1000 kilograms. The levers will then be in equilibrium
when a test weight of one kilogram is placed at X". The slider Q¹ is then put in the
O notch and the slider Q put in the last notch (indicating 1000) on the scale of
hundreds. Under these conditions the levers should again be in equilibrium. They
should also be in equilibrium when the slider Q is put in the notch indicating
900 kilograms the slider 9 being in the notch indicating 100 kilograms or the scale
of units. The graduations from zero to 10,000 kilograms may be verified in this
manner and by adding weights at ✗" the same process may be applied up to 10, 20,
50 or 100 thousand kilograms in the case of larger machines for example.
The action of the improved weighing apparatus is thus enabled to be verified
without the employment of the heavy weights heretofore required.
The steelyard or lever R may evidently be arranged either in the manner herein-
before described with reference to the drawings or it may be arranged in any other
suitable position and be combined in any suitable manner with the platform
levers. The connections of the tension rod X or of the balancing weight S or any
other point of suspension may be modified and hooks or pans for the reception of
weights may be placed in any suitable positions for verifying the levers under the
platform as well as the relations of the principal levers or lever arms
or other lever performing the same functions. Figures 4, 5 and 6 are diagrams
(-10)

page_text: showing combinations of levers acting on the same principles as that hereinbefore
described with reference to Figures 1 and 2 but not constructed in the proportion of
10 to 1 as in the arrangement firstly described.
The results obtained with these arrangements illustrated in the diagrams are the
same as in the apparatus hereinbefore described namely.
According to the arrangement illustrated in Figure 4 the upper lever or steelyard
is made with equal arms b 6' and the lever arm f can be made of any length pro
vided that its proportion to the arm F makes up or completes the proportion of 1
to 1000 so that a weight represented by 1 at X" balances a weight represented by 1000
F
at P1 and also that'
10.
Figure 5 illustrates another arrangement in which any proportion may exist between
the arms F and provided that the other conditions existing in the preceding arrange
ment are complied with.
Figure 6 illustrates another arrangement in which the upper steelyard is made with
equal arms and the arm f may be of any length provided that its proportion to the
arm F makes up or completes the total of 1 to 1,000 and 10 as in Figure 4.
The following formulæ show the proportions of the levers in the several diagrams.
F
=
Having now particularly described and ascertained the nature of the said
Invention and in what manner the same is to be performed I declare that what I
claim is
First. A weighbridge or other apparatus for measuring weight or force in which
the levers are so proportioned and arranged that the accuracy of its indications can
be tested or verified by means of test weights representing relatively small known
fractions of the weights or forces to be measured the said test weights being
employed substantially as herein before described with reference to the accompanying
drawings.
Second. In a weighbridge or platform weighing machine the combination of a
series of platform levers reducing the weight or pressure transmitted to an indicating
apparatus provided with a lever or steel yard connected to the platform levers on the

page_text: one hand and to a second lever or steel yard on the other hand the proportions of the
said platform levers and steel yards being so calculated that a known or test weight
suspended from a given point on the first steel yard produces the same effect on the
system of levers as a known multiple of the said weight placed on the bridge or
platform and thus enables the accuracy of the mechanism to be checked or verified
without placing standard weights upon the bridge or platform substantially as herein
before described and illustrated in the accompanying drawings.
Third. A weighbridge or platform weighing machine in which the bridge or plat-
form is caused to act upon two steelyards through levers reducing the weight trans-
mitted in suitable proportions one of the said steelyards being provided with scale
pans or their equivalents for the reception of test weights and with two graduated
scales and sliding weights indicating units and hundreds respectively the other
steelyard being provided with a graduated scale and weight indicating thousands
the levers and steelyards being so proportioned that the effect of any known weight
upon the bridge or platform can be accurately reproduced by applying a fraction of
such weight at a certain point or points on the first steelyard substantially as and for
the purpose hereinbefore described with reference to the accompanying drawings.
Fourth. The weighbridge arranged and operating as herein before described and
claimed in combination with a stand or pillar M having a box or recess for the
reception of the test weights when not in use substantially as hereinbefore described
and illustrated in the accompanying drawings.
Fifth. The arrangements and combination of parts constituting the improvements
in weighing apparatus substantially as hereinbefore described with reference to the
accompanying drawings.